bs_7982-impacto ambiental de incendios involucrando plasticos

8/19/2019 BS_7982-Impacto ambiental de Incendios Involucrando Plasticos

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DRAFT BS 7982

Guidance on environmental impact of large-scale fires involving plastics materials


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Table of contents

Page

Introduction 3

1 Scope 4

2 Terms and definitions 4

3 Plastics and fire 6

4 Overview of relevant regulations and guidance documents 6

5 Introduction to fires 9

6 Decomposition products from burning plastics 13

7 Potential environmental impact of fires 17

8 Experience of large-scale fires involving plastics 27

9 Mitigation measures 31

Annex A Bibliography 36


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Introduction

The European Union‘s Directive 96/082/EEC, commonly referred as the ‘Seveso II’ Directive, wasimplemented in the United Kingdom in 1999 as the COMAH (Control of Major Accident Hazards)regulations. It aims to minimise the consequences to people and the environment where accidents haveoccurred.

COMAH applies to a wide range of activities including the storage, use and manufacture of largequantities of ‘dangerous substances’. It should be noted that plastics are not considered to be ‘dangeroussubstances’ per se. As such, COMAH does not apply directly to plastics. However, some of thechemicals used, such as pentane, are ‘dangerous substances’ for the purposes of COMAH and as aconsequence, it is possible that COMAH may apply to some sites.

‘Dangerous substances released from fires are not taken into account in deciding the scope of COMAH.However, where COMAH applies, respecting the complexity of fires and the releases that can occur as aconsequence, the possibility exists that burning plastics may release potentially dangerous chemicals acautious approach. Most importantly, COMAH emphasises the need site specific risk assessment, orincidents and their consequences, including the consequences for people and the environment as well.Most importantly, the COMAH emphasises the need for site operators to not only assess the risks ofincident but also its consequences for people and the environment as well.

The competent authority for COMAH lies jointly with the Health and Safety Executive (HSE) and theEnvironmental Agency in England and Wales; and with the HSE and the Scottish Environment

Protection Agency in Scotland.

During the last few years, a number of incidents at plastics storage sites involving hundreds of tonnes ofplastics have focused the attention of the public on the consequences and the safety issues that resultfrom storing plastics. This document is aimed to complement the Home Office document that relates togeneral plastic materials.


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1 Scope

The purpose of this British Standard is to provide guidance to site operators, emergency planners andlocal authorities on the likely environmental impact of ‘large scale’ f ires involving significant quantities ofstored plastics. This includes:

- stocks of plastics raw materials prior to or during manufacture;

- stocks of fabricated articles after manufacture;- stocks of articles for sale i.e. in warehouses;- stocks of articles awaiting recycling.

Environmental impact of effluents from incinerators and power stations is not included.

NOTE 1: Stocks of finished plastics and rubber articles at point of sale (e.g. garden centres) that contain very largequantities of plastics form a further category. This however is different from the first four because large numbers ofpeople may often be involved. This category could be referred to in a separate annex, as would a major plastics fireon a ship. Rubber tyres are not within the scope of this standard as they are the subject of separate guidanceissued by the Home Office.

NOTE 2: Whilst rubbers and rubber products are not specifically covered in the title of this standard, much of theguidance may also be applied to them as well as to plastics. As there are many similarities in chemical

composition between thermoplastic elastomers and more rigid thermoplastic and the fire effluent from thesefamilies of products are similar. Much of the guidance issued by the Home Office on storage of rubber tyres maybe used as a example of how to manage large stocks of plastic products.

2 Terms and definitions

For the purposes of this document, the following terms and definitions apply:

2.1additivesubstance added to polymers to improve or modify one or more properties

2.2asphyxiant gasesgases that incapacitate victims by starving the body of oxygen, resulting in impairment of the nervousand cardiovascular systems causing loss of consciousness and ultimately death

2.3environment

surroundings in which an organisation operates, including air, water, land, natural resources, flora, fauna,humans, and their interrelation

2.4environmental impact

any change to the environment, whether adverse or beneficial, wholly or partially resulting from anorganisation’s activities, products or services

2.5establishmentbuilding or premises under the control of an operator where plastic or rubber materials are present in oneor more installations, including common or related infrastructure or activities (adapted from 96/082/EEC)

2.6“exotic” organic compoundsorganic compounds that may be toxic at very low concentrations such as certain polychloro- andpolybromo-dibenzodioxins/furans and organophosphates.

2.7


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fillerrelatively inert solid material added to a plastic to modify its strength, permanence, working properties orother qualities, or to lower costs (ISO 472)

2.8fire effluenttotality of gases, and/or aerosols (including suspended particles) created by combustion or pyrolysis(ISO13943, Fire Safety – Vocabulary )

2.9foamed plastic (cellular plastic)plastic in which the density is reduced by the presence of numerous small cavities (cells),interconnecting or not, dispersed throughout the mass.NOTE A foamed plastic often is called simply a foam. Rigid foams normally have a closed-cell structure whilstflexible foams have an open-cell (interconnecting) structure

2.10hazardintrinsic property of a plastic or rubber material or physical situation, with a potential for creating damageto human health and/or the environment (adapted from 96/082/EEC).

2.11installationtechnical unit within an establishment, in which plastic or rubber materials are produced, used, handledor stored. Includes all the equipment, structures, pipe work, machinery, tools, private railway sidings,docks, unloading quays serving the installation, jetties, warehouses or similar structures, floating orotherwise, necessary for the operation of the installation (adapted from 96/082/EEC).

2.12irritantseffluents that cause immediate painful sensory stimulation of the eyes, nose, throat and lungs, resultingin behavioural incapacitation and impairment of breathing. Additionally, they can cause inflammatorylung reactions and oedema which also result in impairment of respiration and may ultimately prove fatalseveral hours, or even days, after removal from a fire atmosphere

2.13major accidentmajor emission, fire, or explosion resulting from uncontrolled developments in the course of theoperation of any establishment, and leading to serious danger to human health and/or the environment,immediate or delayed, inside or outside the establishment, and involving dangerous materials(96/082/EEC).

2.14operatorindividual or corporate body who owns or operates an establishment or installation or, if provided for bynational legislation, has been given decisive economic power in the technical operation thereof(96/082/EEC).

2.15 plasticmaterial which contains as an essential ingredient a high polymer and which at some stage in itsprocessing into finished products can be shaped by flow. Thermoplastic elastomeric materials, flexiblepolyurethane foams and coated frabics are included for the purpose of this document.

2.16PM10a mass median aerodynamic diameter of 10 micrometres or less.

2.17pyrolysisthat part of the irreversible chemical decomposition caused solely by a rise in temperature (ISO 13943)

2.18risk


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likelihood of a specific effect occurring within a specified period or in specified circumstances(96/082/EEC).

2.19storagepresence of a quantity of plastic or rubber materials for the purposes of warehousing, depositing in safecustody or keeping in stock (adapted from 96/082/EEC).

2.20

thermoplastic, nounplastic material capable of being softened repeatedly by heating and hardened by cooling through atemperature range characteristic of the plastic and, in the softened state, of being shaped by flowrepeatedly into articles by moulding, extrusion or forming

2.21thermoset plasticplastic material that has been cured by heat or by other means such as radiation, catalysts, etc., into asubstantially infusible and insoluble state

2.22LC50when lethality is the observed response, the term LC

50 is used to denote the concentration of

material or fire effluent that produces death in 50% of the animals for a specified exposure time.

2.23dioxins/furans:abbreviated terms for certain polychloro- and polybromo-dibenzodioxins and dibenzofurans

3 Plastics and fire

The use of plastics in our modern society has increased over thirty-fold in between 1970 and 2000.Plastics, or synthetic polymers, are chemically similar to natural polymers such as wood, paper, cottonand wool. These are all comprised largely of carbon, hydrogen and oxygen, and thus can burn. Although

their combustibility characteristics are similar, special precautions are required where large concen-trations of plastics products become involved in a fire.

The thirteen types of plastics covered comprise most of the material likely to be encountered. All plasticscan be divided into two categories, melting or thermoplastic and non-melting or thermoset. As heat isapplied to thermoplastic products there will be deformation followed by shrinkage, melting and finallycombustion of vapourised material. The melting point for most thermoplastics is in the range 75 ºC to250 ºC.

Cooling of the molten masses may result in the formation of a bridge or shell covering a hot pool ofmolten, smouldering and/or flaming plastic. Thorough and prolonged cooling with a water fog isnecessary. In the case of cellular plastics (e.g. insulation, packaging) breaking up of clumps and the useof hoselines are recommended.

As heat is applied to thermoset products there is no deformation, shrinking or melting but decompositionof the plastic takes place and the material once ignited will burn.

Plastics require higher temperatures than natural polymers before they will ignite. Flash ignitiontemperatures of natural polymers are 250 ºC to 270 ºC whereas those for synthetic polymers arenormally 310 ºC to 540 ºC. However, once ignited they may burn fiercely and may generate largequantities of smoke. The amount of smoke will depend on not only the material but also its shape,ventilation, size of fire, presence of other materials etc.

Since most burning plastics generate toxic gases during combustion, wearing of self-contained breathingapparatus before entering a fire scene is strongly recommended. Smouldering materials, especially inpoorly ventilated locations, generate carbon monoxide (CO), an odourless, colourless and tasteless gas

and this may present a hazard in premises even after the major part of the fire has been extinguished.


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In this guide the major products of combustion are not listed in order of significance and there will bemany other products of combustion in minor quantities. The ones listed are known to be generated inquantities and/or concentrations that may be harmful.

Pre-planning in order to determine in advance where large stocks of plastics are stored is important inorder to ensure that appropriate action is taken in the case of a fire in order to minimise any negativeenvironmental impact.

Though this British Standard principally deals with the impacts of burning of plastics, such fires often also

involve the collateral burning of building elements. This can result, in particular, in the release of fibrousmaterials used in roofing and insulation products. In the case of older buildings, this may be asbestosand both individual fibres and larger lumps of material can be deposited over a wide area.

4 Overview of relevant regulations and guidance documents

4.1 The Fire Precautions Act 1971

The Fire Precaution Act 1971 requires the owner or occupier of premises such as factories, offices,shops and railway premises to obtain a fire certificate. A f ire certificate is required if there are:

a) more than twenty people working in the same building at the same time, orb) more than ten people working in the same building at the same time, excluding those employeesworking on the ground floor.

c) factory premises where flammable or explosive substances are stored in or under the factory.

In cases of low fire risk, it is possible to be exempt from this requirement (e.g. The Fire Safety and Safety of Places of Sport Act 1987 ).

The Framework Directive (89/391/EEC) and the Workplace Directive assign responsibility to theemployer for ensuring health and safety in the workplace, making reference to the role to be played byfire risk assessments. As an employer, part of the responsibilities concerning health and safetyembraces the need to assess the possible risks resulting from a fire.

The Directives dealing with fire safety have been implemented through the Fire Precautions (Workplace)Regulations 1998, as amended 1999 . This is supplemented by the Home Office Guidance on Workplace Regulations, 1999.

4.2 The Building Regulations 1991

These regulations apply to new and altered buildings in England and Wales and have been made underthe Building Act 1984. They specify procedures, including f ire safety requirements, concerning healthand safety of people in buildings. Guidance on how to meet requirements of the Building Regulations1991 is given in Approved Document B: Fire Safety, 2000.

4.3 Health and Safety at Work

The Health and Safety at Work Act 1999 places an obligation upon employers to provide and maintainworking conditions that are safe and without risk to the health of employees, so far as is reasonablypracticable. The scope of the Health and Safety at Work Act extends to the storage of highly flammablematerials, the control of flammable vapours and dusts, standards of housekeeping, safe systems of workand the control of sources of ignition.

The obligations of employers concerning the implementation of the Health and Safety at Work Act isprovided in The Management of Health and Safety at Work Regulations 1992 (the Management Regulations). The Regulations, as with the Health and Safety at Work Act itself, apply to all workactivities.

Part of the Regulations places a requirement upon employers to undertake a risk assessment. For thosecompanies with fiv e or more employees, significant risks must be recorded in the risk assessment. Foran office, undertaking a risk assessment procedure is relatively straightforward. However, for activities


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such as those that occur at a nuclear power station or chemical plant, the procedures are much moreonerous.

The Control of Substances Hazardous to Health (COSHH) requires employers to avoid exposure byworkers to hazardous substances or, in those cases where this is not possible (eg a laboratory), to ensurethat adequate procedures are in place to maintain control. COSHH requires employees to comply withcontrol measures and, where appropriate, to record any weaknesses in the systems in place to theiremployer.

4.4 Seveso II Directive

The Control of Major Accident Hazards (COMAH) Regulations have been issued to implement theSeveso II Directive (96/082/EEC) which aims to minimise the consequences to people and theenvironment where accidents have occurred. COMAH replaces the UK Control of Industrial Major Accident Hazards (CIMAH) Regulations 1984 , implemented following the fi rst Seveso Directive.

Responsibility for implementing the Seveso II Directive lies jointly with the Department of theEnvironment, Transport and the Regions (DETR) and the Health and Safety Executive (HSE)

The Seveso II applies to a wide range of activities including the storage, use and manufacture of largequantities of dangerous chemicals. It places additional responsibility on operators of establishments todocument their major-accident prevention policy and to ensure that it is properly implemented (article 7).Operators are also required to produce a safety report to document those procedures put in place toprevent major accidents or, in those instances where accidents have occurred, to limit their consequencefor man and the environment. Such safety reports shall be made publicly available.

4.5 DETR guidance on Seveso II Directive

A guidance document on the Seveso II Directive has been written by the Institute of Terrestrial Ecologyfor DETR. This will allow users to interpret and implement the Directive.

It is expected that the revised guidance will help operators and regulators to:

a) clarify what constitutes a major accident to the environment;

b) indicate what constitutes a long-term or significant consequence for the environment of a potential oractual accident;

c) identify sources of information about the environment that can be gathered at a scale appropriate toa site-based regulatory regime; and

d) understand the relationship between the Seveso II Directive and the provisions of other pieces oflegislation concerned with protecting or enhancing environmental quality.

4.6 HSE guidance documents

The Health & Safety Executive publishes a number of documents aimed at assisting site operators tofulfil their obligations, e.g.:

a) Guidance Note EH 70: “The control of fire-water run-off from CIMAH sites to prevent environmental damage ”. This document provides guidance to help operators of CIMAH sites concerning thearrangements in place to deal with water used to fight fires on their sites. It outlines the basic f ireprecautions, the emergency planning (risk assessment) and the control measures to be taken if therisk assessment indicates that the fire run-off might cause damage to the environment.

b) Guidance Book HSG 64: “Assessment of fire hazards from solid materials and the precautions required for their safe storage and use ”. This guide provides general principles to help thoseindividuals legally responsible for assessing fire hazards arising from flammable solid materials. Theguide also provides assistance with fire precautions in the workplace.

c) Guidance Book HSG 92: “Safe use and storage of cellular plastics ”. This document providesguidance on the control of fire hazards concerning cellular plastics. It is aimed at manufacturers,converters, users and occupiers of storage premises.


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4.7 Other guidance documents

a) Fire Safety — An Employer's Guide

b) Chemical Industries Association (CIA) “Guidance on chemical warehouse fire safety – key questions for managers concerned with the protection of warehouses against fire ”. This document is aquestionnaire intended to prompt managers to review their own arrangements in key areas ofwarehouse fire safety.

c) Loss Prevention Council, report SHE 14: 1997 “Assessment of pollution risks ”. The procedureoutlined in this report provides a framework for developing cost effective systems for assessingpollution risks, (1) occurring on a particular site, and (2) having off-site consequences which arealways location-specific and often related to geographical features.

d) The Fire Protection Association, “Guide to Building Fire Protection ”. This document provides anoverview of the key factors affecting fire safety in industry and commerce for those responsible forbuildings.

e) The Fire Protection Association, “Fire Risk Management in the Workplace ”. This document providesguidance on methods of fire risk assessment, analysis of such assessment to reduce the risks andimprove fire safety.

f) The Fire Protection Association, “Safe practice in storage areas ” (GP6), “Outdoor storage ” (GP7).

These documents give guidance on good practices for storage management.

g) “Environmental sampling after a chemical accident ” DETR, 1999 (HMSO)

h) “Ch emical incident management for local authority environmental health practitioners ” Chemicalincident response service, Guy’s & St Thomas’ NHS Trust.

i) "Managing Fire Water and major spillages " Pollution Prevention Guidelines 18, Environment Agency

5 Introduction to fires

5.1 Classification of fires (BS EN 2: 1992)

The British Standard BS EN 2 classifies fires into four categories defined in terms of the nature of thefuel:

Class A: fires involving solid materials, usually of an organic nature, in which combustion normally takesplace with the formation of glowing embers.

Class B: fires involving liquids or liquefiable solids.

Class C: fires involving gases.

Class D: fires involving metals.

Fires involving plastic or rubber materials are typically Class A fires although if the fire results in ‘run off’of melted plastics, these fires may be classified as Class B.

5.2 Flammability principles

The science of fire protectioni

rests upon the following principles:

a) an oxidising agent , a combustible material , and an ignition source are essential for combustion. Inthe context of this report, the combustible material is a plastic or rubber material and the oxidisingagent is the oxygen of the air;

b) the combustible material has to be heated to its piloted ignition temperature before it can be ignitedor support flame spread;

c) subsequent burning of a combustible is governed by the heat feedback from the flames to thepyrolysing or vaporising combustible. The burning rate of large fires is principally governed by the

radiant heat transfer from the flames to the pyrolysing fuel surface.

d) burning will continue until either of the following occurs:


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the combustible material is consumed;

the oxidising agent concentration is lowered to below the concentration necessary to supportcombustion;

sufficient heat is removed or prevented from reaching combustible material to prevent furtherfuel pyrolysis; and

the flames are chemically inhibited or sufficiently cooled to prevent further reaction.

5.3 Possible environmental impactsFigures 1 and 2 are schematic representations of possible environmental effects in the open and inenclosures.

The fire water from firefighters' hoses can threaten natural waterways as well as drains and sewers.

Figure 1 a) – Fires in the open — No wind – smoke travels mainly vertically, unaffected by wind

Ground Level

Smoke plu me

Flames

Wate r run o f f

Burn ing p last icso r rubbe r

Figure 1 b) – Fires in the open — Windy day, scenario 1 : Smoke blown by wind downstreamwith little settling near fire (wind blowing from left)


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Groun d Level

Smoke plu me

Flames

Water ru n o f f

Burn ing p last icsor rubber

Figure 1 c) – Fires in the open — Windy day, scenario 2 : Smoke blown downwind and quicklyfalls to ground level (wind blowing from left)

Smoke

Ground levelGround level

(i) Single storey buildingFast travel of smoke under ceiling dispersed by

obstacles such as lintels

(ii) Multi-storey buildingFast spread of smoke to upper storeys via stairwellsand lift shafts

Figure 2 a)– Fires in enclosures e.g. large buildings, tunnels, ship, shopping malls, airports andsports stadiums - Fires at developing stage

Ground level

Wind direction

Smoke

Fully developed fire in building with smoke escape to atmosphere cf figure 1b); smoke scenarios as

figure 1a) or 1c) are also possible.


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Figure 2 b) – Fires in enclosures e.g. large buildings, tunnels, ship, shopping malls, airports andsports stadiums - Fires at developed stage

5.4 Fire development in enclosures

Large-scale fires are complex events and are at the forefront of current fire research. Their behaviourdepends on many parameters, which include the level of ventilation, fire load, structure of the buildingand the burning properties of the combustible materials.

The various phases of a fire are summarised in Figure 3. This figure represents a fire development thatassumes no involvement of firefighters or active fire protection systems such as sprinklers.

Fully Developed Fire

Growth

Ignition point

Initiation

Decay

Flashover Time

T e m p e r a t u r e

Figure 3 - The various phases of a fire

Phase 1 - Initiation and early growth

The combustible material (either plastic or rubber material) is heated by a heat energy source (i.e.cigarette, burning paper in a wastebasket, etc…). The ignition source must be able to generate enoughheat to start the ‘decomposition’ of the adjacent combustible material.

The critical parameter for this phase is the ease of ignition.

Phase 2 - Fire growth

As adjacent material is ignited, flames spread and the temperature rises. The surrounding combustiblematerials (e.g.: stacks of plastic materials) may become hot enough to decompose and give offflammable gases. If this ignites, then there may be a ‘flashover’ and the rate of flame spread increasesdramatically. The fire in the original compartment is out of control.

The important parameters for this phase are the rate of heat release, rate of smoke generation and flame

spread.

Phase 3 - Fully developed fire

During this phase, all of the combustibles within the fire compartment are burning. In addition, this is thestage where the fire may spread to adjacent rooms or other buildings.

The important parameters for this phase are fire resistance and structural characteristics of the firecompartment as well as the heat released and smoke and toxic gases generated.

Phase 4 – Decay

During the decay stage, the fire is exhausting its supply of combustibles and/or oxygen. In the case of

oxygen depletion, the fire may appear to have burnt out. However, smouldering combustion cancontinue and, if the full oxygen concentration is restored, combustion may be restored in an explosivemanner. This is also known as a ‘back draft’.


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Events during the various phases of a fire

Fire alarm

Evacutation time minutes.

Firefighting time hours.

Post-fire clear up time days.

Environmental monitoring months.

5.5 Fire hazards of materials

5.5.1 Fire Initiation

The ease with which plastics can be ignited when exposed to various ignition sources depends on thechemical composition of the polymer and concentration of fire retardants as well as on the intensity andduration of exposure to the ignition source. Physical conditions such as thickness of product, ventilation,presence of air-gaps, relative humidity, ambient temperature, etc., will also significantly affect ignitabilityand early fire growth. Direct contact with ignition sources is not the only threat to fire initiation since

radiant heat from flames at the seat of the fire may be significantly intense (e.g. > 35 kW/m2

) thatplastics stored too closely may be raised to temperatures above their ignition threshold.

5.5.2 Fire Growth

The heat released from ignited materials is generally regarded as the most important characteristic whichgoverns how large a fire may become. The rate of heat release and the heat of combustion (MJ/kg) ofplastics and rubbers vary widely; for example, polyolefins will give significantly higher rates of heatrelease than aromatic or halogen-containing polymers. Plastics and rubbers with high rates of heatrelease can cause a flashover in small enclosures relatively quickly.

Fire growth may also be manifest in flame spread. Vertical flame spread (e.g. up high stacks of storagecontainers) can be particularly fast. Lateral flame spread rates depend more on geometric conditions

(e.g. influence of ceilings on rooms and corridors). A further flame spread mechanism which occurs withthermoplastics is downward spread due to flaming drops, which effectively can move a fire at ceilingheight to floor level with the risk of involving other materials positioned on the floor. Thermal propertiessuch as melting and slumping may contribute to fire spread if the material already is sustaining a flame;in some fires, these same properties with materials which have not ignited can delay fire growth byeffectively removing combustible material away from the seat of the fire.

Flame spread is limited in its rate and extent if plastics and rubbers form chars or intumesce when theyburn; both these mechanisms help to protect combustible material below the charred or intumescedlayer. Similarly, plastic laminates or composites which have non-combustible or limited combustiblefacings (such as steel sheet, plasterboard or cementitious coatings) will show less tendency to spreadflame than unfaced plastics.

5.5.3 Smoke Generation and Spread

Some plastics generate significant quantities of hot smoke which is often black and which spreadsquickly away from the seat of the fire. There is a major hazard to people near f ires of this type since thesmoke will rapidly reduce visibility and induce disorientation. This can increase escape times for theoccupants of the premises, which can result in them becoming trapped and inhibit rescue teams. Someplastics and rubbers produce sooty smoke which can lead to significant and widespread deposits, whichrequire high clean-up costs.

Most smoke is buoyant and in open scenarios, smoke plumes do not generally hazard life. However, coldsmoke is often generated (e.g. due to pyrolysis behind non-combustible layers) and this smoke canspread at ground level.

If people are trapped in smoke, the survival times can be short depending on the concentration ofnoxious fumes and on the irritancy of fumes and particles present in the smoke.


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6 Decomposition products from burning plastics

The initial decomposition is generally through pyrolysis by which plastics are broken down by heat toyield a range of organic fragments. These fragments vary in size and chemical structure and provide thevolatile fuel for combustion, ultimately generating oxides of carbon and water.

The elemental composition of a material can provide some guidance when predicting the possiblecombustion or decomposition products that may be generated during a plastics fire. The molecular

composition or structure of a polymer can affect combustion efficiency and the mix of organiccombustion products generated in a fire. Within a fire atmosphere the polymer backbone may be brokendown by pyrolysis into its original structural units (monomers). For example, styrene may be producedfrom polystyrene and similarly PMMA can give rise to the methyl methacrylate monomer.

For almost all combustible materials, including plastics, the main compositional elements are carbon,hydrogen and oxygen and the majority of combustion products will consist of releases derived from theseelements. Initial pyrolysis of plastics, however, yields a series of aliphatic hydrocarbons (e.g. alkanes,alkenes) from methane upwards. Ring cyclisation reactions can result in the formation of alicyclicproducts (e.g. cyclohexane, cyclopentene) and aromatic compounds (e.g. benzene). If a plastic containsoxygen, or if decomposition occurs in air, oxygen can be incorporated into pyrolysis products to yieldcarbonyl compounds (e.g. aldehydes, ketones) and other oxygenated species (e.g. aliphatic alcohols,phenols).

The presence of other elements, arising either from the polymer structure (for example, nitrogen inpolyamides and chlorine in PVC) or from the inclusion of additives, will give rise to additionaldecomposition / combustion products. Examples of potential decomposition products for some of thecommon plastics and their additives according to elemental composition are shown in Table 1.

The relative yields of the various combustion/pyrolysis compounds depends mainly upon the conditionsof thermal decomposition.

- Smouldering fires involve slow thermal decomposition under oxidative non-flaming conditions. Theseconditions give rise to fire emissions that are rich in organic compounds.

-Well v entilated flaming fires provide eff icient combustion conditions (e.g. a high air : fuel ratio) and the

major products are carbon dioxide, water and heat.

- Ventilation controlled flaming fires result in high yields of carbon monoxide, carbon dioxide, hydrogencyanide, smoke, inorganic acid gases and organic products. In the context of potential impacts to theenvironment, beyond the burning building itself, large ventilation controlled flaming fires are deemed tobe potentially the more environmentally significant.

Table 1 – Types of plastics and their decomposition products

Material Major decomposition products(apart from carbon monoxide, carbon

dioxide and water vapour)

Notes

ThermoplasticsPolyolefinesPolyethylenePE-HD, PE-LDPolypropylenePPPolyethylene-vinyl acetateEVAC (copolymer)

Partially oxidised organics includingaldehydes (acrolein, formaldehyde),alcohols (methanol), acids (formic, acetic)and lower molecular weight hydrocarbonsincluding aromatics like benzene andtoluene.

See footnote onplastics compounds

PolyvinylchlorideCompoundsPVC

Hydrogen chloride, aliphatic and aromatichydrocarbons (alkanes , benzene),acrolein, formaldehyde, acetone

Depending oncombustion conditions,very low

concentrations of vinylchloride monomermay be detectable, as


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well as phosgene andchlorinateddibenzodioxins andfurans.


PolystyrenePS

Aldehydes such as formaldehyde andbenzaldehyde and aromatic hydrocarbons

(benzene, styrene, naphthalene)

Most PS productsgenerate heavy black

smoke when theyburn.


PolyestersPolycarbonates (PC)Polyethylene terephthalate(PET)Polybutylene terephthalate(PBT)

Aldehydes, ketones, alcohols and acidicspecies including benzoic and terephthalicacids; low molecular weight hydrocarbons


AcrylicsPolymethyl methacrylatePMMAPolyacrylonitrilePAN

PMMA:MMA monomer, oxidised organics (esters,acids, alcohols etc), hydrocarbonsPAN:Nitrogen-containing species includingnitrogen oxides, hydrogen cyanide,ammonia, organic nitriles including ANmonomer


Polyamides(PA, nylon)

Nitrogen-containing species includingammonia, hydrogen cyanide, nitrogenoxides; formaldehyde, acetaldehyde,ketones, organic acids, hydrocarbonsincluding benzene


Polyphenylenes

Ethers (PPE, PPO)Etherketones (PEK, PEEK)Sulphides (PPS)Sulphones (PES, PSU)

PPE, PPO: phenol, acetonePPS, PES,PSU,: sulphur-containingspecies such as SO2 and, generally atlower concentrations, hydrogen sulphide,carbon disulphide; hydrocarbons such asstyrene and methane, phenol.

Polyoxymethylene Formaldehyde See footnote onplastics compounds

FluoropolymersTetrafluoroethylene polymers

(PTFE) and co-polymers(FEP, PFA, ETFE)Polyvinylidene fluoride(PVDF)Polyvinyl f luoride (PVF)Polychlorotrifluoroethylene(PCTFE)Ethylene-chlorotrifluoroethylenecopolymer (ECTFE)

Hydrogen fluoride (HF) and trace quantitiesof low molecular weight fluoro-organic

compounds such as monomers, oligomersand carbonyl fluoride,In the case of PCTFE and ECTFE, somechlorinated species including HCl.

(ref.: BuildingResearch

Establishment ReportFire Safety of PTFE-based materials usedin buildings, DAPurser, PJ Fardell andGE Scott, 1994, ISBN085125 6538)

Thermosetting resinsPhenol-formaldehyde

(PF)Urea-formaldehyde (UF)Melamine-formaldehyde

Formaldehyde, phenol, methane, acetone,

acetaldehyde, propanol, formic acid, and,in the case of UF and MF, nitrogen-containing species such as nitrogen itself,

See footnote on

plastics compounds


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(MF) ammonia, hydrogen cyanide, oxides ofnitrogen and amines

Polyurethanes (PU) Hydrogen cyanide, ammonia, nitrogen,NOx, amines, isocyanates, nitriles,hydrocarbons, alcohols and aldehydes


Unsaturated polyesters Oxidised organic species such as alcohols,aldehydes and acids (e.g. phthalic acid),hydrocarbons such as styrene and benzene


Epoxy resins Phenol, formaldehyde, formic acid,

acetone, hydrocarbons.Nitrogen-containing resins may give rise toammonia, hydrogen cyanide, amines,isocyanates and nitrogen oxides.

See footnote on

plastics compounds

Polyimides Ammonia, benzene, phenol, aniline

Note 1Ref: Assessment of Plastics Fires (Beurteilung von Kunststoffbraenden): Bavarian Department of theEnvironment Report (Annexes II-IV, BimSchV)

Note 2 Plastics compoundsMost commercial plastics contain additives such as those listed below. The presence of additives should be taken

into account when assessing the hazard of decomposition products produced by plastics raw materials andproducts when they burn. In the case of flame-retardant compounds, for example, decomposition products thatmay be of significance include heavy metal derivatives and chlorinated or brominated organic species.

Fillers Mostly inorganic substances such as calcium carbonate, silicate, aluminium hydroxide

Plasticizers organic acid esters (phthalates etc) or phosphoric acid esters (e.g. triphenyl phosphate)

Flameretardants

Inorganic: antimony trioxide, hydrated alumina, zinc borate

Organic: Organo-phosphorus and organo-tin compounds; chloro-, bromo- and non-halogenated phosphoric acid esters; brominated organics: various aliphatic, alicyclic andaromatic compounds and combinations; chlorinated organics: chlorinated aliphatic and cyclo-aliphatic compounds and phthalates

Miscellaneousadditives

Pigments, lubricants, stabilisers, antioxidants

Information on the environmental pathways and impacts of these decomposition products within the widerlocal environment of a plastics fire are provided by:

• toxicity data: usually expressed as an LC50 (Lethal Toxic Potency) value over a time period and isobtained from exposing animals to mixed test emissions from burning materials or from observing theeffects of individual fire gases on animals and humans. Large scale tests are the most valuablesource of information as they mimic “real” fires most closely. Data from small scale tests is difficult tovalidate with respect to real f ire conditions as the tests are far removed from a full scale f ire.

• MEL and OES are guidance levels for a range of substances, and have been defined for workplacesunder The Control of Substances Hazardous to Health Regulations 1994.

• EAL (Environment Assessment Levels) are those set by the Environment Agency in relation to controlof emissions in relation to the Environmental Protection Act, 1990. They tend to be stricter than MELand OES guidance levels, reflecting the potential greater sensitivity of individuals in the widerenvironment, and potentially longer exposures.

• WHO (World Health Organisation) guidelines provide air quality standards for a range of air pollutantslargely for the protection of human health.

• NAQS (the UK National Air Quality Strategy) has identified a range of air quality objectives, includingseven standards which are specified in the Air Quality Regulations, 1997, and which are required tobe achieved by 2005.

7 Potential environmental impact of fires


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A wide variety of pollutants may be emitted in plastic fires. This pollution may follow a number ofpathways to impact on human and ecological receptors. A risk assessment may not be possible for allpotential impacts but contingency planning should take account of selected “worst case” scenarios.

7.1 Impact zones

In assessing potential environmental impacts of toxic releases from plastics fires, four major zones ofimpact have been considered (see appendix B):

Fire zone: The area within the fire zone (generally the burning building), relates primarily to the actualfire and the corresponding emergency response. To date a myriad of research has been carried out onthe physical and toxic hazards to human health, associated with fires emissions inside burning buildings.Within this zone the priority response must relate solely to the health and safety of individuals who maybe within the burning building. The environmental impacts should be a secondary consideration. Thesewill be considered after the incident and will relate primarily to ash disposal and fire-water run-off outsidethe immediate fire zone.

This guide does not attempt to repeat the extensive and comprehensive works of others in this area andwill concentrate more fully on impacts to the environment within fire plume, plume deposition andsurface water run-off zones.

Fire plume zone : The fire plume zone is an area over which the emissions plume from the fire disperses.Both local topography and meteorological conditions (wind speed and air stability characteristics) willhave an influence on the characteristics of dispersion and the extent of the fire plume zone. Short termenvironmental impacts are most significant in this zone. Valleys, basins, high buildings and streetcanyons, adjacent to, or surrounding the fire constrain dispersion of the plume. Low wind speed,temperature inversion and conditions that promote rapid plume grounding will all limit plume dispersion.The combined effects of topographical features and meteorological conditions that result in restricteddispersion are generally additive and will result in higher air pollutant concentrations within the fireplume.

Plume deposition zone The plume deposition zone encompasses the area under the fire plume zone andtherefore, in a similar way to the fire plume zone, is influenced by topographical features andmeteorological conditions. The extent of the deposition zone is defined by the area where depositionfrom the fire plume occurs. Most particulate deposition will tend to occur closer to the fire source

Air temperature normally decreases with increasing height, the reversal of this trend causes a layer ofwarmer air to overlie a cooler layer - this meteorological condition is known as temperature inversion. Ascool air is heavier than warm air it can not rise, this results in any pollutants emitted below the “warm”inversion layer becoming trapped.

Surface water run-off zone . The surface water run-off zone may include free-standing natural water waysand sewerage, generally ending at either a drain, water-course or confined soak-away area. This zone isparticularly influenced by surface topography, and affects lower-lying areas. Certain regions (e.g.Thames Water region) are served by combined sewerage systems. In running to the combined seweragesystem contaminated fire water could have an adverse effect on biological sewerage treatment workswhich may result in significant pollution to the receiving water course as well as accelerating the time of

travel of pollutants in the fire fighting water to down-stream water intakes.

The chemical nature of fire fighting liquors should be taken into account before consideration is given tothe acceptability or otherwise of their discharge to the public sewerage system. In most cases dilution offire water is likely to be sufficient to minimise the risk but in some cases specialist clean-up and removaltechniques may be required.

Pollution Prevention Guidelines 18 published by the Environment Agency assist in the identification ofthe equipment and techniques available to prevent and mitigate damage to the water environmentcaused by fires and major spillage.

7.2 Release pathways and impacted receptors

The main types of emission releases, and potential release pathways are summarised below, togetherwith the various environmental impacts that potentially could arise.


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7.2.1. Releases to atmosphere

The dispersion of the fire plume within the atmosphere causes:

• elevated concentrations of airborne pollutants• increased risk from exposure to airborne pollutants• reduced visibil ity.

Visual impairment occurs during fires as a result of atmospheric particles reducing visibility by scatteringand absorbing light. This issue tends to get lower priority than other environmental aspects because

there is no associated biological toxicity or clearly definable cost; however, it results in a pervasivereduction in environmental quality. “Urban particles”, formed by gas-to-particle conversions(condensation of volatiles from combustion smoke, or photochemical formation of ammonium sulphatefrom ammonia and sulfur dioxide SO2, for example) are in the size range which accumulates in theenvironment and also scatters light effectively. Visual impacts of airborne plumes from plastics fires willbe temporary, and similar to other types of fires (and are not assessed further in this document).

Risk from atmospheric pollutants is attributable to:• direct inhalation by humans and animals• contact with flora and fauna

There are potential effects on indoor air quality of both naturally ventilated and forced-ventilatedbuildings in the vincity/downwind of a plastics fire.

7.2.2. Deposition to land and water

Atmospheric releases may also affect terrestrial and aquatic environments through deposition ofpollutants. These may potentially cause visual soiling that is similar to that damage caused by other fireeffluent, and are not therefore, considered here.

Many thermal degradation products may condense on, or be adsorbed by, the soot particles and betransported with the smoke.

There may also be deposition on structures leading to corrosion, particularly from acidic decompositionproducts such as Sulphur dioxide (SO2 ) and HCl. Damage (erosion) to stone buildings from SO2 ismainly due to rapid deposition of gaseous SO2 to wet stone surfaces rather than the effects of acid rain

itself. Regions of stone protected from acid rain tend to have a blackened appearance resulting from thedeposition of particles. The particles, together with dry deposited gases, such as SO 2, produce acrystalline gypsum lattice within the stone work interstices. Pressure from the crystal growth breaks offsmall areas of stone, also exposing a more vulnerable surface. SO 2 also reacts with other materials suchas zinc on galvanised steel (corrugated iron, electricity pylons) and can react with paint, paper andleather. Similarly, hydrochloric acid attacks metal materials, machines, electrotechnical and electronicequipment which are not directly affected by fire. This can cause considerable corrosive damage.

Health and ecological damage can arise from exposure to deposited pollutants though a variety ofpathways such as:

• aerial deposition to water and land• accumulation in the food chain (e.g. fish, crops) and subsequent consumption, either directly or

indirectly, of contaminated food.

7.2.3. Releases through surface water run-off

The use of fire fighting water could potentially release contaminated surface water run-off to thesewerage system, to storm drains or to surface waters. Such water run-off could also drain togroundwater. Such water could potentially contain contaminated ash. Potential local visual impacts mayarise from this run-off, but these are not considered significant. Exposure to contaminated water run-offreleases may occur through various pathways:the drinking of contaminated surface waters or groundwater;releases to water courses where water-borne contaminants have direct impacts on aquatic species;the consumption of contaminated food (e.g. fish) in which water-borne contaminants have accumulatedthrough the food chain;

7.2.4. Ash disposal


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The disposal of ash following a fire may also release contaminants to the environment if the disposalprocess is not properly managed. Ash dust may be released following a fire as it dries, and the processof collecting and disposing of the ash may also produce dust. Exposure to pollutants within the ash couldpotentially occur by:

direct inhalation of fugitive dust emissions produced following a fire and particularly during ash storageand removal;through improper disposal of ash at a landfill where contaminants are subsequently released.

7.2.5. Impacted receptors

For those pollutant pathways where exposure to products decomposition is the primary concern, thepotential impacted receptors are as follows.

i) Humans. Examples include, children, the elderly, individuals with respiratory and other diseases andpregnant women. Clearly, where a fire occurs under conditions of restricted dispersion, the location ofsuch groups (for example, schools and hospitals) relative to the course of the fire plume needs to betaken into account. Some members of the population will be more susceptible to the affect of airborneirritants/axphyxiant gases through inhalation.

ii) Soils and crops . Soil may be contaminated to some extent from primary deposition, which may onlybecome apparent over the longer term. Contaminated soils potentially represent a hazard through the

various pathways of:

• direct ingestion;

• through take -up by crops, and accumulation within the food chain.

iii)Terrestrial habitats and species. Certain plant species will be more sensitive to air pollutant emissions(particularly HCl) and deposition products that others. Taking into account the vast variety of responses,and the lack of detailed data for more than a few of these plants, it is not considered useful to identifyindividual sensitive species/ crops. The component of the terrestrial environment which received thehigher load from atmospheric deposition tends to be the flora, rather than the soil

ii, iiias plant surfaces

are extensive and exposed to the atmosphere.

iv) Freshwater / marine habitats and species . Species found in streams / watercourses are variouslysusceptible to different pollutants.

v) Property and equipment. Some effluents from plastics fires are corrosive

7.3 Impacts from short term exposures

The impacts of short term exposure (i.e. the impact occurring within minutes to a few hours of a fire) willpertain mostly to the local environment, within the fire plume zone and surface water run-off zone. Asummary of potential short-term exposure effects of plastic fires is given in table 2.

Table 2 - Possible short term exposure effects

Potential exposure /pathways

Asphyxiants Irritants Toxic/Carcinogens

Exoticorganics

Air exposure - effects onhuman health

potential impactsin fire zone only

potentialimpacts in firezone and infire plumezone

no short termeffects

no shortterm effects

Air exposure - effects onterrestrial habitats/ species

no short termeffect

potentialimpacts in fireplume zone


no shortterm effect

Deposition on Land -effects on crops andvegetation

no short termeffect



no shortterm effect

Deposition/ run-off Water -effects on human health

no short termeffect

potentialimpacts from

potentialimpacts from

no shortterm effect


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(via drinking) local run-off tosurface waters

local run-off tosurface waters

Deposition on Water -effects on freshwater/ marine habitats andspecies

no short termeffect

potentialimpacts fromrun-off tosurface waters

potentialimpacts fromrun-off tosurface waters

no shortterm effects

The impacts from short term exposure arising from atmospheric releases are principally associated withasphyxiant gases and irritant gases / smoke. Most toxic / carcinogenic and exotic organic releases areunlikely to be produced in sufficiently high concentrations so as to result in short term impacts and formany (such as dioxins) toxicity only occurs through long term exposures (addressed under long termimpacts) and acute toxicity through dioxins is reportedly unknown.

Short term impacts to water, from elevated soluble toxics / carcinogens and irritants in fire water run-off,draining within a local catchment will represent worst case impacts on natural water courses andassociated aquatic habitats/ species.Impacts to land, through deposition, from plastics fires are unlikely to result in short term impacts.

7.3.1. Impacts to Air

7.3.1.1. Impact of asphyxiant gases on human health

Plastic fires inside buildings produce asphyxiant gases, particularly carbon monoxide (CO) and hydrogencyanide (HCN), which represent a major hazard. Within the fire zone the emitted gases and smoke fromthe fire may accumulate and concentrate. Narcotic effects, caused by the common asphyxiant gases,result in impairment of the nervous and cardiovascular systems causing loss of consciousness followedultimately by death from suffocation.

Smoke will continue to cause intoxication until such a time as it is released and dispersed into theatmosphere where concentrations of these gases are subsequently rapidly reduced through dispersion.

Key pollutants of concern are CO and HCN. Measured levels within the fire zone ( ref. Iv, v and vi) leadto LC50 and STEL levels given in table 3.

Table 3 - Acute toxic potency values for asphyxiant gases

Key Pollutants LC50 30 minb)

(ppm)STEL

a)

(mg/m3)

CO 2000-4000 232

HCN 170-230 11

Note: The lower the LC50 value, the higher the toxic potency.a)

STEL: 50 minutes period. STEL (short term exposure period).

Unless dispersion of asphyxiant gases is extremely constrained, such as when the fire plume iseffectively trapped, then the reduction in concentrations once air is released from a building is not likelyto represent a significant impact outside the fire zone itself.

7.3.1.2. Impact of irritant gases on human health

Irritant gases cause immediate sensory irritation of the eyes, nose, throat and irritation of the lungs.Higher exposure levels result in lung oedema and inflammation, impairment of respiration andbehavioural incapacitation. Effects are observed directly upon exposure and are related to the exposureconcentration rather than an accumulated dose.

As the severity of immediate irritant effects varies over such a wide range of concentrations irritants areimportant as potential causes of adverse human health effects both inside of a burning building and inthe fire plume zone.

Key pollutants of concern are acrolein and hydrogen chloride. Potential levels within the Fire Zone aresummarised in Figure 7.3. ISO has published International Standard, ISO 13314, titled “Determination ofthe Lethal Toxic Potency of Fire Effluents” incorporating guidelines for the rank-ordering of the major firegases according to their acute toxic potency

Error! Bookmark not defined.. The ISO guide indicates that acrolein,


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HCN, NO2, SO2 are reportedly 10-30 times more toxic than CO and HCl (see table 3 and table 4).Additionally, HCl has been shown to be a much weaker respiratory tract irritant than acrolein and otherpartially oxidised combustion products which are present in all fires

3. Data shows that although the

mechanisms of action of HCl and CO are totally different, their lethal doses are v ery similar.

Table 4 - Acute toxic potency values and short term exposure limits for some irritant gases

Key Pollutants Impacts Significance

LC50 30 min

(ppm)

STELa)

(mg/m3)

hydrogen chloride (HCl) 3 800(b)

8

hydrogen bromide (HBr) 3 800(c)

10

hydrogen fluoride (HF) 2 042-3 500(b)

2.5

nitrogen dioxide (NO2) 127-200(b)

9.6

sulphur dioxide (SO2) 400(c)

13

acrolein 150(c)

0.7

formaldehyde 750(c)

2.5a)

STEL: 50 minutes period. STEL (short term exposure period).b)

LC50 values are for humans i v

.c)

Test species not known 3

Note: The lower the LC50 value, the higher the toxic potency.

The data suggests that various irritant gases can cause potentially significant impacts within the fireplume zone.

Worst case circumstances are likely to arise within the fire plume zone resulting from irritant gasesreleased under conditions of low dispersion (low wind speed), temperature inversion and rapid plumegrounding. Such effects can be amplified in valleys / basins and in urban areas where are air flow isrestricted (such as street canyons and emission sources surrounded by high buildings). This can beaggravated where the fire plume is emitted from a low source.

7.3.1.3. Impact of irritant gases on habitats/ species

The irritant gas hydrogen chloride is both corrosive and reactive. On entering leaf stomata the gas reactsimmediately with intercellular tissue creating characteristic foliage burning symptoms.Although chronic exposure to HCl gas can result in plant mortality, short term (acute) injury to plantsceases once the source has dissipated and plants usually recover. Potential damage to vegetation islikely to be restricted to the fire plume zone.As a result of its corrosive nature HCl is unique among common f ire gases in that its concentration in thegas phase decays by reacting rapidly with most construction surfaces, which limits its transportation. IfHCl comes into contact with water or humidity hydrochloric acid forms which, when released into theatmosphere, is immediately diluted to such an extent that large scale or long term environmentaldamage does not occur.

Key pollutants of concern are summarised below in table 5.

Table 5 - Summary impacts of irritant gases on habitats/ species


HCl Only very local potential impacts Unlikely to have significantimpact on vegetation.

The data suggests that HCl is unlikely to have significant impacts on vegetation within the fire plumezone, though a few sensitive species (particularly lichens) may suffer mortality as a result of a f ire event.

Worst case circumstances are likely to arise within the fire plume zone under conditions of low dispersion(low wind speed), temperature inversion and rapid plume grounding. Such effects can be amplified invalleys / basins.

7.3.2. Impacts to water


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Of all the viable exposure routes to water from toxic releases from plastics fires, those related to firefighting water run-off are considered to represent the major potential impact upon the environment in theshort term. Such a situation may occur if run-off waters directly enter aquatic habitats in surface waters(e.g. rivers, streams, ditches), within the immediate vicinity of the site, and where levels of toxic releasesare particularly high.

7.3.2.1. Impact of toxics and irritants on human health

Short term impacts may arise where fire water run-off is used for drinking water during or immediately

following a fire. The effects are very local to the fire, where the run-off water is potentially most highlycontaminated with ash / soot / decomposition products, and relatively undiluted. The likelihood of suchwater being directly ingested is small, but such surface water bodies do represent a potential hazard.Key pollutants of concern are as those defined in 7.3.3.2.

These impacts to water will be exacerbated where the contours of the land are such that run-off isconducted directly to surface waters (non-contained) and where dilution effects are limited (low flowrates, small water volumes within the receptor and a short source to receptor pathway).This exposure risk is probably best addressed as a potential, temporary health and safety hazardassociated with affected watercourses.

7.3.2.2. Impact of toxics and irritants on freshwater/ marine habitats and species

There may also be short term effects associated with high pollutants loads (toxics and irritants) from firewater run-off suddenly released into streams / watercourses. In worst cases, there is the potential formortality of fish and other aquatic fauna and flora. Key pollutants of concern are summarised in table 6.

Table 6 - Summary of toxic and irritant impacts on freshwater/ marine species

Key pollutants Impacts Significance

MeasuredConcentrations

(a)

µµµµg/l

CEC: MAC(b)

µµµµg/l

Ammonia - 500

Hyrogen cyanide - 50

Phenol 5 630 -Toluene 370 -

Aluminium 11 320 500

Antimony No Data 10

Cadmium 336 5

Chromium 111 50

Copper 8 180 3 000 (guide level)

Iron 35 500 200

Lead 5 810 50

Manganese 2 779 50

Nickel 180 50

Zinc 70 500 5 000 (guide level)(a) Maximum concentration measured in the fire water run-off during theOntario fire.(b)

MAC: Maximum Admissible Concentration - where no MAC value isavailable the EC guideline value has been given.(EC Drinking waterdirective)

Aquatic bioassays, carried out following the Ontario plastics fire Error! Bookmark not defined.

demonstrated thatwater in the storm sewer (to which the fire water run-off was discharged) was lethal to aquatic life,although these toxic effects were not found to extend to larger receiving waters.

The irritants phenol, toluene, cyanides and ammonia are also harmful to the aquatic environment when

released in large concentrations, and before they are substantially diluted.


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The information available suggests that this pollutant pathway is potentially significant and potentiallyrepresents a real risk of environmental damage to local aquatic ecosystems.

Impacts on aquatic life will be exacerbated where the contours of the land are such that run-off isconducted directly to natural surface waters (non-contained) and where dilution effects are limited (lowflow rates, small water volumes within the receptor and a short source to receptor pathway).

In some cases impacts can be minimised and mitigated by dilution where releases are discharged tolarge / fast flowing water bodies. In other cases releases can be contained and treated, or drained

through the foul sewer system.

7.4 Impacts from long term exposures

Long term environmental impacts from exposures to plastic fire decomposition products (i.e. the impactsoccurring after the fire that impacts over the longer term, up to a period of years) will be experiencedlargely within the local environment, within the fire deposition zone and along impacted streams/ watercourses. A summary of potential long-term exposure effects of plastics fire emissions is given intable 7.

Table 7 - Possible long-term exposure effects

Potential exposure /pathways

Asphyxiants Irritants T oxic/Carcinogens

Exoticorganics

Air exposure -effects on humanhealth

no long termeffects

no long termeffects

no long termeffects

no long termeffects

Air exposure-effects onterrestrial habitats/species

no long termeffects

no long termeffects

no long termeffects

no long termeffects

Deposition on Land- effects on cropsvegetation andthrough food-chain

no long termeffects

no long termeffects

Potentialimpacts

potentialimpacts

Deposition/ Run-offWater - effects onhuman health (viadrinking)

no long termeffects

no long termeffects

Potentialimpacts

potentialimpacts

Deposition onWater - effects onfreshwater/ marinehabitats & species,and through food-chain

no long termeffects

no long termeffects

potentialimpacts

potentialimpacts

7.4.1 Impacts to land

7.4.1.1. Impact of general pollutants on crops and through food chains

Key pollutants of concern are summarised in table 8.

Table 8 - Summary impacts of general pollutants on crops

Key pollutants Impact levels Significance

MeasuredConcentrations

(a)

mg/kg

UK: ICRCL(b)

mg/kg

Metals

Antimony No Data -Cadmium 3.7 3

Chromium 32 600 (total Cr)


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25 (Cr (VI))

Lead 220 500

Polycyclic aromatic hydrocarbons(PAH)

6466 (total - in soot) 500

Benzo[αααα]pyrene 262 mg/kg (in soot) -(a)

Maximum concentration measured in the soils during / after the Ontario fireError!

Bookmark not defined..

(b)Interdepartmental Committee on the Redevelopment of Contaminated Land

“action” concentrations for soil (where a range of ICRCL values exists the moststringent criteria have been listed in this table).

In every fire PAH are produced and they are included amongst the cancer causing compounds.However, PAH are reported to adsorb strongly to soot particles, which results in low bio-availability.Analysis of soot from the fire at Dusseldorf airport found total PAH levels of 6466 mg/kg soot, withbenzo[αααα]pyrene concentrations of 262 mg/kg

v.

A recent studyvi

has been undertaken to investigate PAH dispersion and deposition to vegetation andsoil, following a large scale polypropylene fire. PAH concentrations under the plume deposition areawere found to be elevated in grass shoots (by up to 70 fold) and in soil (by up to 370 fold). Lighter PAHswere found to disperse into the environment at greater distances (up to 4.5 km) than the heavier, more

hydrophobic PAHs. Particulate deposition of PAH occurred closer to the fire source compared to vapourphase deposition. For all PAHs, the fire was shown to result in greater contamination of soils comparedto grasses, with the ratio of plant:soil contamination decreasing as hydrophobicity increased.

Metals reportedly used in high concentrations in plastics are: cadmium (Cd), antimony (Sb), lead (Pb),zinc (Zn), chromium (Cr) and copper(Cu)

xiii. (Although the use of cadmium has been restricted since

1991 it may still be present in older plastics, particularly those found at recycling facilities.) Studies toidentify toxic heavy metals emitted to the atmosphere, or remaining in the ash phase during laboratoryscale combustion of plastics have shown that the main areas of concern relates to the presence of lead,cadmium, antimony and chromium. Cd, Pb, Sb and Cr were found as major, minor and tracecomponents in the smoke and / or ash phases of almost all sampled plastic materials

vii, viii, ixwith

concentrations of Pb, Sb and Cr ranging from 0.1 ppm up to, and including, % levels. Both Cd and Pbcan enter the body through the food chain.

During the f ire in Ontario Error! Bookmark not defined.

elevated concentrations of Ni, Cr and lead were detectedwithin the smoke plume in the vicinity of the fire. Several metals (including Ni, Cr, Zn, Cu, Mn, V, Fe &Pb were detected in soot samples taken from areas both near to and far from the fire. Heavy metals thatreach the soil can may also contaminate groundwater and enter the food chain .

Following a fire at a recycling plant fire in a Scots pine region, studiesx

have reported food-chain transferof Cadmium within the ecosystem. The study indicated that cadmium released into the environment fromthe chemical accident was bioavailable and entering the food-chain at all the trophic levels investigated.Bioaccumulation was observed in all organisms investigated and bio-concentration was observed ininvertebrates (woodlice and earthworms). Cd was also found to be present at elevated concentrations inwood mice and bank voles - showing that Cd is mobile throughout the food-chain. However, no evidencewas found for biomagnification occurring through the bank vole food-

chain or through the omnivorous wood mouse food chain (of which seeds (particularly), invertebrates andvegetation constitute a large part). Both higher and lower plant tissue can reportedly accumulatemoderate amounts of Cd with relatively little damage.

Due to low solubility and relative freedom from microbial degradation Pb has a long residence time whenreleased into the environment compared to most other pollutants and its compounds tend to accumulatein soils and sediments

vii. The population most likely to be affected would be the very young and the very

old or sickly people since their accumulation of heavy metals would be more pronounced because ofunderdeveloped or damaged excretionary systems. There has also been growing concern for the effectsthat low concentrations of lead may have in the development of mental impairment in young children

ix.

Information available on metal and PAH accumulation through the food chain and the potential threatthis may pose to human health is contradictory. The study considers that a prudent approach is justifiedand that pollutant pathways through the soil may be potentially significant, though the critical sources,pathways and ultimate receptors will all be important considerations.


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The worst case is likely to be represented by a situation where crops are grown within the plumedeposition zone, and relatively closer to the source where highest deposition is likely to occur. Potentialrisks of contamination of soils and crops can be checked through monitoring.

7.4.1.2. Impact of exotic organics (2.6) on crops and through food-chains

Key pollutants of concern are halogenated dibenzodioxins and dibenzofurans some of which arepersistent organic pollutants and carcinogenic.

Dioxins and furans deposited in the environment may consumed by domestic animals. Investigation ofdioxin and furan accumulation in wood mice following a factory PVC fire revealed that TEQs were 9-foldhigher in mice 10m from the factory boundary than those caught at 200m

xiand suggested that the

dispersion of dioxins and furans from large scale fires may be considerable. Dioxins and furans at thesite were taken into the wood mouse food chain, resulting in high liver residues. The residues appearedto cause increased liver weight compared with animals from a non-contaminated site, indicating that thedioxin and furan levels in the livers may have resulted in physiological damage. In this instance dioxinsand furans were found to be bio-available to terrestrial animals following releases from accidents

Conversely, reviews of the results from investigations in Germany, with regard to PVC fires, showed thatdioxin and furan emissions were much lower than expected and in most cases levels were within normalbackground measurements

3. All investigations concluded that dioxins and furans are most likely to be

found adsorbed to soot (which is already hazardous) and as such are not likely to be bio-availableFollowing a PVC fire in 1992, dioxin testing was carried out on soil, water, plants and crops; the resultsrevealed negligible levels of dioxins to be present.

In another investigation of 200 fires involving chlorinated plastics, increased dioxin concentrations werefound at 90% of the sites

xii.

Research ( R Weber et al) at the University of Tuebingen, Germany, has addressed the question ofwhether polyfluorinated dibenzodioxins (PFDDs) and polyfluorinated dibenzofurans (PFDFs) can beformed during thermal decomposition of fluorinated polymers by mechanisms similar to those occurringin the case of chlorinated and brominated organic materials. Published work indicates the followingdifferences between fluorine-containing and other halogenated materials.

i) No of PFDD or PFDF was detected under conditions known to produce PCDD and PCDF

ii) No formation of PFDDs or PFDFs was detected during the thermal decomposition ofpolytetrafluoroethylene (PTFE)

Organophosphates represent a further class of exotic organics that similarly may present a risk throughaccumulation within the food chain.

Overall, these results show that exotic organic pollutants may represent a potential environmentalimpact, though insufficient information is presently available on likely risks of significant accumulationlevels, or the likely critical sources, pathways and receptors.

The worst case is likely to be represented by a situation where crops are grown within the plumedeposition zone, and relatively closer to the source. Potential risks of contamination of soils, andtherefore crops, can be checked through monitoring.

7.4.2. Impacts to water

7.4.2.1. Impact of toxics/ carcinogens/ exotic organics on human health

There is the possibility of long term impacts arising through direct ingestion of toxic/ carcinogenic/ exoticorganic compounds in water courses contaminated by fire water run-off, and/or from plume deposition.The concentrations involved are likely to have been subject to dilution.

Key pollutants of concern are summarised in table 9

Table 9 - Summary of toxics/ carcinogens/ exotic organics on human health


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Measured Concentrations(a)

µµµµg/l

CEC: MAC(b)

µµµµg/l


Cadmium 336 5

Lead 5 810 50

Nickel 180 50Zinc 70 500 5 000 (guide level)

Dioxins/ furans 210 pg/l TEQ -

Organophosphates No Data -

PAH 172 200(a)

Maximum concentration measured in the fire water run-off during theOntario fire

Error! Bookmark not defined..

MAC: Maximum Admissible Concentration - where no CEC MAC value isavailable the CEC guideline value will be given

.

Monitoring data from the Ontario fireError! Bookmark not defined.

demonstrated that levels of metals were high

in the fire water run-off although these levels decreased with dilution into surface waters and with time.Surface water exceeded local objectives for several metals - Al, Cd, Cu, Pb, Ag, Zn.

Monitoring data from the plastics fire in Ontario revealed very high concentrations of six PAH in firewater run-off (including naphthalene, fluorene, phenanthrene and anthracene). As PAH have lowsolubility and are formed during incomplete combustion their presence in fire water run-off was notsurprising

Error! Bookmark not defined.. Levels of PAH were observed to be lower in the storm sewer outfalls /

surface waters and concentrations declined further with time.

The information available suggests that various pollutants are potentially significant where long termcontamination of drinking water has occurred, which would imply drinking water abstraction.

The worst case is likely to be represented by a situation where fire water run-off transports significant

quantities of ash into natural water-courses that are subsequently used for drinking water abstraction.

7.4.2.2 Impact of toxic/ carcinogens and exotic organics on freshwater / marine habitats andspecies and through the food-chain

Toxic/ carcinogenic/ exotic organic compounds in surface waters can directly impact freshwater habitatsand species. Marine habitats and species may also be affected, though due to dilution, the impacts arelikely to be less.

Key pollutants of concern are summarised in table 10.

Table 10 - Summary of impacts of toxic/ carcinogens & exotic organics on freshwater / marine

habitats & species and through the food-chain

Key pollutants Impacts Significance

Measured Concentrations(a)

µµµµg/l

CEC: MAC(b)

µµµµg/l


Cadmium 336 5

Lead 5 810 50

Antimony No Data 10

Chromium 111 50

Zinc 70 500 5 000 (guide level)

Dioxins/ furans 210 pg/l TEQ -

Organophosphates No Data -

PAH 172 200


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Aluminium accumulates on specialised cells on fish gills that are responsible for maintaining sodiumbalance. All fresh water animals have a higher salt concentration than the water they live in - if theyexcrete more salt than they absorb they will die.

On the third day of the Ontario fireError! Bookmark not defined.

elevated dioxin concentrations (up to 5.5 pg/LTEQ) were measured at the outfall to the harbour. Dioxins pose an indirect threat to aquatic life as theycan accumulate slowly through the food chain. One of the main sources of dioxin for humans isconsumption of contaminated fish (as well as dairy and beef products).

These results show that some toxics / carcinogens / exotic organic compounds are potentially significantin accumulating within aquatic based food chains. However, insufficient information is presently availableto identify likely risks of environmental damage, and is subject to the critical sources, pathways andreceptors concerned .

The worst case is likely to be represented by a situation where simple aquatic based food chains arisee.g. fish to man.

8 Experience of large-scale fires involving plastics

8.1 Locations

Plastic materials are used in a large range of applications. It is therefore important to anticipate thelikely environmental impact of fires involving plastics or rubbers. These may occur under a range ofcircumstances and across the ‘life cycle’ of the plastics and rubbers as listed below.

a) Manufacturing sites . The quantities of plastics stored at manufacturing facilities can exceed 20,000tonnes. Storage is either in stacks or silos (ranging from 25 to 300 tonnes each).

Usually, only one type of material is stored at these sites and the operators know the composition ofthe material stored.

b) Distribution sites . Distribution sites typically have up to 2,000 tonnes material stored. Some sitesonly store one type of material. Others offer a range of material. Storage is mainly in stacks.

As with the manufacturing sites, site operators are aware of the exact composition of the materialsstored.

c) Converters . Converters typically use plastics materials that contain additives (i.e. flame retardant,colourant, plasticiser, etc). Their storage facilities rarely exceed 1,000 tonnes. All types of materialsare found: plastics, additives and f inished products, packaging materials as paper, cardboard orwood (pallets). Site operators do not necessarily know the exact composition of their materials.

d) Retailer, commercial outlets : commercial outlets and retailers store all types of plastics and rubbers.As thousands of different types of material can be stored on the same site, operators don’t generallyknow the composition or the exact quantity of each type of material.

e) Recyclers : Plastic products are increasingly being recycled. Accordingly, recycling centres have

responded by increasing their storage facilities. Presently, storage capacity at these sites is notmore than 1,000 tonnes. The materials found in a recycling facility are, most often the recyclableplastics and rubber products, i.e. mainly the polyolefins (PE, PP), polyvinyl chloride (PVC),polyethylene terephthalate (PET), acrylonitrile-butadiene-styrene (ABS), and polycarbonate (PC).

8.2 Examples

8.2.1 Manufacturing site

On 9 October 1995, a fire occurred in a warehouse of a polypropylene producer at the Wilton site inCleveland (UK). It occurred in a large building with dimensions 100m x 200m, and which containedapproximately 10,000 tonnes of materials, stored on pallets. Some products were also stored in an openstorage area next to the building.

The construction of the building comprised a steel frame, bricks wall and a concrete floor. Plastic lightdiffusers made of poly(methyl methacrylate (PMMA) were used in the lighting system. Rooms were


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separated by sliding doors. The building was part of a chemical production site, which contained variousstorage and production facilities, including an organic peroxide store.

The cause of the accident appeared to be a malfunction in the electrical lighting system leading tooverheating of a PMMA light diffuser. This ignited, and the flaming droplets ignited polypropylene thathad been stacked underneath the light.

The fire detectors on the sliding doors failed to operate and accordingly the fire was not detected until itwas well established. When fire brigades arrived at the scene, the fire was already well developed.

With a strong wind and open loading-bay door, oxygen supply was unlimited. As the polypropylenemelted, it dripped and ran whilst burning, this contributed to the spread of the fire. Roof lights alsoignited, and assisted in spreading the f ire further via flaming droplets. Burning debris was carried by thewind toward the outside storage area, which easily ignited and burnt.

The fire was finally brought under control and extinguished, and did not burn itself out. The fire fightingoperations lasted 8 hours and involved 200 fire fighters. A strong wind was the main factor in hamperingfire f ighting efforts.

The predominant materials involved in the blaze were polypropylene and building and constructionmaterials.

Polypropylene is an olefin plastic (i.e. composed of hydrogen and carbon). It burns very easily and with ahigh temperature. In some places of the building, steel frames disappeared suggesting that thetemperature at these locations was higher than 1500

oC.

Air: Despite the occurrence of a large, black plume of smoke, there was no evidence of anyenvironmental impacts resulting from air emissions, immediately after the fire. The weatherconditions of that day allowed slow vertical and moderate horizontal dispersion. There were nosensitive natural areas (pasture, lake etc) in the surroundings of the incident.

Water: The water run-off entered the drainage system of the Wilton complex. The effects of the firewere, most likely, diluted in the site drainage system by the large volume of water used to extinguishthe fire; and

Soil: No information was found concerning the possibility of soil contamination from the smoke

plume and soot deposition. As the f ire occurred in a large industrial area, it is assumed that anylocal soot deposition was washed toward the drainage system.

It would appear from the evidence available that this incident had no measurable impact on theenvironment, nor on the health of locals. This can be explained mainly due to the elemental compositionof polypropylene, and the weather conditions at that time which allowed for good atmospheric dispersionof the pollutants.

8.2.2 Storage sites (converters) (limited information only)

a) Following a fire at a polyethylene storage facility in Harlow, Essex on 25 February 1994, the Instituteof Terrestrial Ecology

xiiianalysed the heavy metal contamination (lead, cadmium and zinc) of a grassland

site adjacent to the fire. The analysis was based on samples collected one day after the fire. In total,

1000 tonnes of materials were destroyed during the blaze. Levels of contamination measured were up to4.5 times higher than normal background levels.

b) Soil and water run-off analysis was performed following a fire at a warehouse in Langer,Nottinghamshire on 3 April 1994, containing 1000 tonnes of cling film (plastified PVC)

xiii. Samples were

collected both from the drainage ditch and the stream along side of it. The results showed levels ofcontamination with antimony (Sb) downstream the site. Soil analysis of samples collected under thedirection of the plume after it had dispersed, did not reveal significant contamination with antimony.

8.2.3 Recycler site - example 1

8.2.3.1 General

On 9 July 1997, a fire occurred at plastics recycling facility in the urban area of Hamilton, Ontario,Canada. The fire began about 7:45 p.m. on July 9

thand ended in the morning of July 12

th.


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The Ontario Ministry of Environment and Energy (MOEE) has produced a detailed report on theenvironmental impact of the fire as a result of contaminants released. The complete report c

bs_7982-impacto ambiental de incendios involucrando plasticos

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