SEARCH

SEARCH BY CITATION

Keywords:

  • particles;
  • aerosol;
  • size distribution;
  • PAH;
  • isocyanates;
  • ISO/TS 19700 steady-state tube furnace

ABSTRACT

  1. Top of page
  2. ABSTRACT
  3. INTRODUCTION
  4. EXPERIMENTAL METHODOLOGY
  5. RESULTS AND DISCUSSION
  6. CONCLUSIONS
  7. ACKNOWLEDGEMENT
  8. REFERENCES

This study has examined the distribution patterns between gas phase and particle phase of some chemical compounds produced in fires. It has also addressed the question of the distribution of individual particle-associated species between the different size-ranges of particles. The chemical compounds studied and discussed in this paper are polycyclic aromatic hydrocarbons (PAHs), and isocyanates.

The steady-state tube furnace, ISO/TS 19700, was chosen as the physical fire model in order to study the production of particles from different types of fire exposure, that is, oxidative pyrolysis, well-ventilated flaming fires and under-ventilated flaming post-flashover fires.

Two materials were chosen for investigation, a polyvinyl chloride (PVC) carpet and a wood board. The particle production from the two materials investigated varied concerning both the amounts produced and the particle size distributions.

The analysis of PAHs showed that volatile PAHs were generally dominant. However, when the toxicity of the individual species was taken into account, the relative importance between volatile and particle-associated PAHs shifted the dominance to particle-bound PAH for both materials.

The substantial degradation in the tests of the low polyurethane content of the PVC carpet, and the (4,4′-methylenediphenyl diisocyanate)-based binder in the wood board resulted in no or very small amount of quantifiable diisocyanates. Copyright © 2013 John Wiley & Sons, Ltd.

INTRODUCTION

  1. Top of page
  2. ABSTRACT
  3. INTRODUCTION
  4. EXPERIMENTAL METHODOLOGY
  5. RESULTS AND DISCUSSION
  6. CONCLUSIONS
  7. ACKNOWLEDGEMENT
  8. REFERENCES

Studies on particle generation in fires and the mass and number distribution of particles from fires in various building materials and products have shown that the amount of particles produced varies widely depending on the material that burns and on the fire conditions [1]; further, the amount of particles in the smoke that is submicron in size is very high [2, 3]. It is known that submicron particles (i.e. with a diameter less than 100 nm) are easily transported into the deeper parts of the lungs by inhalation, and various studies show that ultra-fine particles are potentially most dangerous [4, 5]. It has also been found that a mixture of ultrafine particles and gases together, can give rise to increased toxicities [6]. Thermal degradation products from fires may condense or be adsorbed by soot particles and be transported along with the smoke into the body [7].

Whether a chemical substance is found in the vapour phase or in the condensed phase associated with particles, may be important in different ways. First, a toxic molecule behaves chemically different depending on whether the molecule is bound to a particle or not, but above all, particle-association gives access to other forms of transport than in the gas phase. Species in the gas phase have a high diffusion rate and reactive molecules could be rapidly absorbed in the respiratory tract mucosa, thereby protecting deeper parts of the respiratory tract. However, a particle-bound substance can be transported much further before contact with the respiratory tract occurs because of the low diffusion rate. A well-known example of potentialisation of toxicity of gases by aerosols is sulfur dioxide (SO2). The effects of SO2 are largely confined to the upper airways except during exercise or if the gas is taken up by a carrier aerosol [8].

Small particles have a higher proportion of surface area per mass than larger particles. Smoke generally contains a high proportion of ultrafine particles [9], where the ultrafine fraction thus should be a major part of the total area available for absorption. It is therefore plausible that substances may be enriched by absorption on the smaller particles. This is thus an important aspect because these particles are easily transported far into the lungs thus increasing the hazard to a human [1].

A group of toxic organic compounds that is largely associated with the particulate phase in fire effluents is polycyclic aromatic hydrocarbons (PAHs). The toxicity of PAHs is due to the fact that a number of PAH species are highly carcinogenic [10]. It has been shown that the often incomplete combustion found in a fire produces significantly more PAHs compared with other combustion sources [9]. The PAH-production from fires has typically been measured as the sum of PAH compounds in the vapour phase and the particle phase. However, there is a need for improved understanding of the proportion of PAHs that is associated with the particulate phase and whether there is an enrichment of specific PAHs on smaller particle sizes.

There are two main reasons that this knowledge is important: (1) PAHs associated with respirable particles can be transported into the lungs where there are opportunities for effective absorption into the body; and (2) exposure is also possible by absorption through the skin (dermal) and mouth (oral). The issue of exposure to PAHs is perhaps most important for people who frequently come into contact with fire, such as fire fighters, where both exposure pathways are plausible.

This paper presents distribution patterns of toxic chemical compounds between gas phase and particle phase. Further, in some cases, it addresses the question of the distribution of individual particle-associated species between the different size-ranges of particles produced in a fire. The chemical compounds studied included PAHs, isocyanates and hydrogen chloride (HCl). PAH is a group of compounds, where some species are carcinogenic and thus having a long-term chronic effect. Isocyanates are a group of toxic species (irritants) that have a high acute toxicity in very low concentrations. Isocyanate exposure may further result in a variety of chronic airway disorders [11, 12]. Isocyanates can also cause hypersensitivity pneumonitis, contact dermatitis, and rhinitis [12]. HCl is an irritant gas with an important role in acute toxicity in fire scenarios. This paper will, however, focus on the work with the organic compounds studied; PAHs, a group of organic compounds with a long-term chronic effect and isocyanates, a group with a direct toxic effect. The steady-state tube furnace, ISO/TS 19700 [13, 14], was chosen as the physical fire model in order to study the production of particles from different types of fire exposure, that is oxidative pyrolysis, well-ventilated and under-ventilated post-flashover flaming fires. Two materials were chosen for investigation: a polyvinyl chloride (PVC) carpet and a wood board material. The complete study is available as a project report [15].

EXPERIMENTAL METHODOLOGY

  1. Top of page
  2. ABSTRACT
  3. INTRODUCTION
  4. EXPERIMENTAL METHODOLOGY
  5. RESULTS AND DISCUSSION
  6. CONCLUSIONS
  7. ACKNOWLEDGEMENT
  8. REFERENCES

Materials investigated

Two different types of materials were selected for fire tests: a PVC carpet and a wood based building board, called ‘wood board’ throughout. These are both commercial products that are commonly found in domestic settings. PVC carpets have shown high production of smoke in previous investigations in contrast to our expectation of the fire performance of wood board [16]. The PVC carpet had a density of 1360 kg/m3, thickness of 2.0 mm, the combustible part was 76.2%, and it contained 29.1 wt% chlorine. The wood board was of oriented strand board (OSB)-type, which is a particle board with relatively large wood particles. It had a density of 580 kg/m3, thickness of 11 mm, and the combustible part was 99.7%. Both products contained isocyanate-based components, the carpet as polyurethane (PUR) lacquer, whereas the wood board contained an isocyanate [4,4′-methylenediphenyl diisocyanate (MDI)]-based binder.

Steady-state tube furnace experiments

The experimental work was conducted using the ISO/TS 19700 steady-state tube furnace [13]. This fire model was selected as it can vary the combustion conditions in a controlled manner and create steady-state conditions for a prolonged period facilitating sampling for chemical analysis [17]. The experimental work was conducted in two test series. The first series of tests (Test series 1) included analysis of particle distribution, PAHs and isocyanates, was conducted at SP Technical Research Institute in Borås, Sweden (Table 1). The second series of tests (Test series 2) that included a more detailed investigation of the particle size distribution was conducted at the University of Central Lancashire (UCLan) in Preston, UK (Table 2). The tube furnace tests nominally followed the ISO/TS 19700 standard; detailed information on the experiments is given in Reference [15].

Table 1. Description of test conducted in Test Series 1.
Test IDMaterialFire stage (fs)
T29, T31PVC1b
T23, T32PVC2
T8, T24, T27, T33PVC3b
T22, T28Wood board1b
T9, T11, T13, T14, T25Wood board2
T10, T15, T16, T30Wood board3b
Table 2. Description of test conducted in Test Series 2.
Test IDMaterialFire stage (fs)
PVC 1, 2, 3PVC1b
PVC 4, 5, 6PVC2
PVC 7, 8, 9PVC3b
Wood board 7, 8, 9Wood board1b
Wood board 1, 2, 3Wood board2
Wood board 4, 5, 6Wood board3b

The method for managing the ventilation conditions in a tube-furnace test is to determine the stoichiometric fuel-to-oxygen ratio for the tested material and to select an actual fuel-to-oxygen ratio for achieving the desired equivalence ratio (ϕ). The fire stages [18] investigated in this work included the following: fire type 1b—oxidative pyrolysis (furnace temperature at 350 °C), fire type 2—well-ventilated flaming fires (ϕ < 0.75, furnace temperature at 650 °C), and fire type 3b—under-ventilated post-flashover fires in large or open compartments (ϕ = 2, furnace temperature at 825 °C).

Sampling of particles

Three different cascade impactors were used for sampling and size characterisation of particles. In Test Series 1, a four-stage Sioutas Cascade Impactor was used primarily for collecting samples of different size distributions for subsequent PAH-analysis. Further, in Test Series 1, a specially made impactor for collecting particle-associated isocyanates was used [19]. In Test Series 2, a Marple Series 290 Personal Cascade Impactor with eight stages was used for a more detailed characterisation of the particle distribution. Samples were collected from the mixing chamber of the tube furnace during the steady-state period of a test in all cases. Note that the sampling was not isokinetic in any of these cases. The flow field in the mixing box of the steady-state tube furnace is not defined, and the non-isokinetic sampling might have influenced the selectivity of the sampled particle sizes. This has not been investigated.

The Sioutas Impactor is a simple cascade impactor, consisting of four impactor stages (25-mm polytetrafluoroethylene (PTFE) plates) and a post-filter (37-mm PTFE filter) (Table 3). A pump maintained a sample flow of 9 l min−1 during the collection period, normally 1 min. It was found that longer sampling times generally led to over-load of the impactor and misleading results. It was found that the Sioutas Impactor was unsuitable for sampling in tests with the PVC carpet because of the high prescribed sampling flow that overloaded the impactor after a short time. Conditioned filter plates were pre-weighed before use, and sampled plates were stored in a desiccator before weighing the amount of particles sampled.

Table 3. Collection stages for the cascade impactor used in Test Series 1.
Impactor stage50% cut-point, aerodynamic diameter (µm)Approximate maximum aerodynamic diameter (µm)
12.52.60
21.00.95
30.500.52
40.250.23
5 (filter)<0.25Backup filter

The cascade impactor used in Test Series 2 had eight impactor stages (34-mm-diameter, stainless steel), and remaining fine particles were collected on the final filter (34-mm-diameter glass fibre filter); Table 4. Fire effluents were sampled at a flow rate of 2.0 l min−1 for 5 min in tests with wood board and for 4 min in PVC-carpet tests. The cascade impactor analysis was always carried out in triplicates.

Table 4. Collection stages for the cascade impactor used in Test Series 2.
Impactor stage50% cut-point, aerodynamic diameter (µm)Approximate maximum aerodynamic diameter (µm)
121.321.5
214.815
39.810
46.06.5
53.54
61.552
70.931
80.520.5
9 (filter)<0.52Backup filter

Total soot content was also determined through sampling of smoke gases from the mixing chamber on a filter. The filter used was an ‘SKC—MCE, low BGD’ (SKC, Inc., Eighty Four, PA, USA) with a pore size of 0.8 µm and a diameter of 37 mm. The sampling flow was 1 l min−1, and the sampling period normally lasted for 3 min. Conditioned filters were pre-weighed before use, and sampled filters were stored in a desiccator before weighing the amount of soot sampled.

Sampling and analysis of polycyclic aromatic hydrocarbon

Samples for PAH-analysis were collected in tests with both the wood board and the PVC carpet in Test Series 1. Two sampling methods were employed. Smoke gases were collected using a commercial PAH-sampler (SKC no.226-30-16 OVS-sampler) where particle-associated and gaseous phase PAHs were separated. In a selection of tests with the wood board, the particles captured on the Sioutas Cascade Impactor collector plates were subsequently analysed for PAH content. The distribution of PAH species could be determined by this combination of sampling methods; between gaseous phase and condensed phase for both materials, and additionally between size classes of particles for the wood board.

The SKC OVS-sampler consists of a particle filter (glass fibre) and a XAD-2 adsorbent. A small piece of glass fibre wool was placed prior to the filter to increase the particle load capacity. The smoke gases were sampled with a flow rate of 1.0 l min−1 during a sampling period of 3 min. The samples were subsequently extracted with toluene, and the filter/glass wool and the XAD-2 adsorbent were treated separately. The extracts were analysed focusing on the 16 Environmental Protection Agency priority pollutant PAH-compounds using gas chromatography–mass spectrometry [15]. The collection plates of the Sioutas Cascade Impactor were analysed for PAH species in selected tests. The collection plates were extracted with toluene before GC-MS analysis.

Sampling and analysis of isocyanates

Air sampling of isocyanates was conducted using three principal methods: an impinger–filter method [20, 21], a dry sampler method [22] and a denuder–impactor method [19, 23]. The denuder–impactor method enables separation gas phase isocyanates and isocyanates associated to different particle size fractions.

Sampling with the impinger–filter method was performed during 1 min using 30 ml midget impinger flasks containing 10 ml 0.01 mol l−1 dibutyl amine (DBA) in toluene and a glass fibre filter in series. Air samples were collected from the mixing chamber using a flow rate of 1.0 l min−1 using glass connections. Two impinger–filter samplers were connected in parallel to one inlet. After sampling was completed, the impinger solutions and filters were transferred to separate test tubes, and internal standard (corresponding deuterium labelled isocyanate-DBA derivatives) was added. The samples were evaporated to dryness and dissolved in 0.5 ml acetonitrile. The isocyanates corresponding urea-derivatives were analysed using liquid chromatography–mass spectrometry/mass spectrometry (LC-MS/MS).

The dry sampler consisted of a polypropylene tube coupled in series with a 13 mm polypropylene filter holder. The inner wall of the tube was coated with an impregnated glass fibre filter (tube-filter, 25 × 60 mm), and a V-shaped impregnated glass fibre filter (V-filter, 13.5 × 60 mm). An impregnated 13 mm round glass fibre filter with a pore size of 0.3 µm was placed (end-filter) in the filter holder. The filters were impregnated with reagent solutions containing equimolar amounts of DBA and acetic acid in methanol. Air sampling was performed for 1 min using assembled and impregnated dry samplers. A flow rate of 0.2 l min−1 was maintained. Three dry samplers were connected in parallel to one inlet (all glass connections). A background was sampled for 5 min between every test using three dry samplers connected in parallel to one inlet. After sampling, the sampler was extracted, as described previously [22], and the sample solution was transferred to vials for LC-MS/MS analysis.

The denuder–impactor (DI) sampler consisted of three central parts: a denuder, a three-stage cascade impactor and an end filter. The denuder collecting gas phase isocyanates and isocyanate associated to different particle size fractions are collected in the different impactor stages (d50 = 2.5, 1.0 and 0.5 µm). Small particles (<0.5 µm) are collected on the end filter. The filters were impregnated with reagent solutions containing equimolar amounts of DBA and acetic acid in methanol. Air sampling was performed for 3 min with a flow rate of 5 l min−1. The denuder, the impactor plates and the end filter were separately extracted and analysed using LC-MS/MS, as previously described [23].

RESULTS AND DISCUSSION

  1. Top of page
  2. ABSTRACT
  3. INTRODUCTION
  4. EXPERIMENTAL METHODOLOGY
  5. RESULTS AND DISCUSSION
  6. CONCLUSIONS
  7. ACKNOWLEDGEMENT
  8. REFERENCES

Particles

The formation of soot particles is closely linked to the formation of PAHs. The first step in soot formation is the particle interception of high molecular weight PAHs to form particle-like structures. These structures can subsequently grow through condensation and surface growth by addition of mainly acetylene. Larger structures can also be formed by coagulation and agglomeration. These larger agglomerates may then be degraded by oxidation reactions. After the particle interception zone, the size of the particles is a few nanometres, whereas they have grown to 20–50 nm after the coagulation zone [24]. When the smoke leaves the flames of a fire and cools, vapour phase PAH condense on the soot particle surface. The amount of condensed organics varies for different fire conditions, from under 20% to up to 50% for well-ventilated and under-ventilated fires, respectively [24].

Polyvinyl chloride-carpet

Particle size-distribution analysis in tests with the PVC carpet was made in Test Series 2. Figure 1(a) shows the particle size distribution for tests with the PVC carpet under well-ventilated condition expressed as relative mass for each size fraction. Results are expressed in terms of the aerodynamic diameter (particle size, D50%) using a log scale on the horizontal axis. The distribution shows a peak at the 3.50 µm stage and followed by lower peaks at the 0.52 and 14.80 µm stages. The particles captured on the 3.50 µm plate, represented about 20 mass% of the particles sampled. An increase of relative particle mass can be seen for the region <0.52 µm.

image

Figure 1. Polyvinyl chloride-carpet relative mass captured on the different impactor plates for (a) well-ventilated conditions, (b) under-ventilated and (c) oxidative conditions.

Download figure to PowerPoint

Figure 1(b) presents results for the PVC carpet for under-ventilated fire conditions. The main peak in the size distribution curve is moved to a smaller particle size compared with the well-ventilated tests, and is centred at the 0.93 µm stage. This is not what was expected from previous experience of other materials and is discussed in more detail later.

Figure 1(c) shows results for the PVC carpet from oxidative pyrolysis conditions. The greatest amount of soot is produced within the size range 0.52–0.93 µm. The particle distribution is concentrated to a single peak in the distribution curve, and there is no trend of an increase of particles for the smallest particle sizes (<0.52 µm) as was seen for tests at well-ventilated and under-ventilated conditions.

Both the well-ventilated and under-ventilated tube furnace experiments gave a major mass-peak at a relatively large particle size diameter, in the order of 1–4 µm. This is large compared with particles from fires with other common materials, which normally have a median aerodynamic diameter around 0.3 µm [9]. In a test with a PVC carpet in previous work [2], a mass-peak was seen at a particle size around 0.35 µm. It should, however, be noted that those tests were conducted with the cone calorimeter (ISO 5660) [25] where the conditions are very well-ventilated [26]. Butler and Mulholland [24] have shown that mass median aerodynamic diameters in the range of 0.4–3 µm, are found from fires with PVC.

The maximum particle-size was found at a somewhat smaller particle size in the under-ventilated tests compared with the well-ventilated tests, which was unexpected. The less complete combustion for under-ventilated conditions should normally result in particles of larger size. However, for PVC, the difference in combustion efficiency is not as significant between these two combustion conditions as halogen free materials. This is because the chlorine in PVC disrupts the combustion reactions in the gas phase and significantly reduces the combustion efficiency even for well-ventilated conditions. Additional factors are the higher furnace temperature and the lower primary air flow in the under-ventilated tests. These factors could possibly result in more efficient oxidation of the soot before the reactions are quenched in the mixing chamber.

The total amounts of particles produced for the different combustion conditions examined varied. The mass-charge yield from oxidative pyrolysis was about half of that produced from well-ventilated conditions. The yield produced during under-ventilated conditions was even higher.

Wood board

The particle size distribution for the wood board material was investigated in both test series, and the results obtained from the two laboratories are very similar. In well-ventilated tests, the maximum in particle mass distribution was found at the smallest sizes studied (<0.25 µm) (Figure 2).

image

Figure 2. Relative particle mass captured on the different impactor plates in tests with the wood board at well-ventilated conditions in (a) Test Series 1 and (b) Test Series 2.

Download figure to PowerPoint

Results from tests with the wood board at under-ventilated conditions are shown in Figure 3. The particle size distribution is similar to that found for well-ventilated conditions, and the results from the two test series are comparable also for this combustion condition.

image

Figure 3. Relative particle mass captured on the different impactor plates in tests with the wood board at under-ventilated conditions in (a) Test Series 1 and (b) Test Series 2.

Download figure to PowerPoint

Results from tests with the wood board during conditions of oxidative pyrolysis are shown in Figure 4. Figure 4(b) shows a solitary peak with the centre at the 0.93 µm plate, and there is no tendency for any rise in the size distribution curve at the smallest sizes. The result from the single test with impactor data from oxidative pyrolysis conditions in Test Series 1, Figure 4(a), shows similar result, but with some differences. The mass distribution peak is, in this case, for the highest fraction of sizes measured (D50 = 2.5 µm), which could be interpreted to indicate that the maximum in this test was skewed somewhat towards a larger particle size compared with the results from Test Series 2. This is, however, difficult to interpret fully as the impactor used in Test Series 2 has a higher resolution than that used in Test Series 1. As only a single test was run in Test Series 1, there is insufficient data to draw any conclusions concerning whether the differences seen are significant or not. Further, the length of the sampling time differed between the two test series. It is, however, obvious from the results from both test series that oxidative pyrolysis conditions result in the production of much larger particles than does flaming combustion.

image

Figure 4. Relative particle mass captured on the different impactor plates in tests with the wood board at oxidative pyrolysis conditions in (a) Test Series 1 and (b) Test Series 2.

Download figure to PowerPoint

In summary, from the tests conducted with wood board, it is seen that small-sized particles are preferably produced during flaming combustion. The difference in particle sizes was not significant between well-ventilated and under-ventilated combustion with the tube furnace. A significantly different particle size distribution was seen in the tests with oxidative pyrolysis conditions where the maximum in particle mass found was skewed towards a larger particle size (Figure 4).

Production of small-sized particles in flaming combustion of wood has been shown previously [2] in well-ventilated tests with the cone calorimeter, where median aerodynamic diameters were found between 0.1 and 0.2 µm. Butler et al. [24] reported median aerodynamic diameters from wood fires mainly in the range of 0.1 µm, but reported also values in the vicinity of 1 µm from a large under-ventilated wood crib fire.

The total amounts of particles produced for the different combustion conditions examined varied strongly for the wood board [15]. The mass-charge yield from oxidative pyrolysis was significantly higher compared with the production from the other combustion conditions. The yields produced during well-ventilated conditions were low compared with the production from under-ventilated conditions.

Comparison of particle yields

The total production of particles, on a mass basis, was generally significantly lower from the wood board compared with the PVC carpet, with the exception of the high production seen from oxidative pyrolysis of the wood board material. For well-ventilated combustion conditions, the particle production was about 10 times higher for the PVC carpet.

One notes that the particle measurements from both tube furnace tests-series gave relatively equivalent results, which indicates that the combustion conditions were comparable and that the particle analysis was reliable.

Polycyclic aromatic hydrocarbons

Polycyclic aromatic hydrocarbons are defined as being comprised of two or more joined aromatic rings. The toxicity of individual PAHs varies widely, and a range of non-cancer and cancer effects have been demonstrated [27]. The PAH that has been investigated the most is benzo(a)pyrene (BaP). BaP is metabolised to oxygenated forms that act as a carcinogen in the body [27]. PAHs can be formed directly from saturated hydrocarbons in vitiated combustion atmospheres. Low molecular mass hydrocarbons act as precursors in the pyrosynthesis of PAH compounds that take place at temperatures above 500 °C. The tendency for fuels to form PAH via pyrosynthesis varies depending on the structure of the basic organic fuel. Although all organic fuels can form PAH, the greatest yields are obtained from aromatic fuels followed by cyclic aliphatics, olefins and paraffins, in decreasing order of magnitude. Thermal break-down of heavier hydrocarbons through pyrolysis is another path to form small unstable precursor compound for PAH synthesis [28].

The PAHs are present in air in the gaseous phase or adsorbed onto particles. The phase distribution of individual PAHs in air is important when assessing their fate because of the difference in rates of chemical reactions and transport between the two phases. The phase distribution of any specific PAH depends on the vapour pressure of the PAH, the ambient temperature, the PAH concentration, the affinity of the PAH for suspended particles (KOC), and the nature and concentrations of the particles [29]. The KOC of a chemical is an indication of its potential to bind to organic carbon in soil and sediment. Low molecular weight PAHs have KOC values in the range of 103–104, which indicates a moderate potential to be adsorbed. Medium molecular weight compounds have KOC values in the l04 range. High molecular weight PAHs have KOC values in the range of 105–106, which indicates stronger tendencies to adsorb to organic carbon [30]. PAHs having two to three aromatic rings are present in air predominantly in the vapour phase. PAHs with four aromatic rings are both present in the vapour and particulate phase, and PAHs having five or more aromatic rings are found predominantly in the particle phase [29].

The PAHs analysed in this study are listed in Table 5. The PAH congeners are numbered after increasing molecular weight. These numbers are later used in this paper for identification of individual congeners. Table 5 further contains information related to phase distribution, cancer classifications from Environmental Protection Agency and International Agency for Research on Cancer, and toxic equivalence factors (TEFs) used for normalising the cancer potential for individual PAH congeners. TEF factors are normalised against BaP, which has a factor of unity. The unit is expressed in toxicity equivalence (BaP-TEQ).

Table 5. Information on the polycyclic aromatic hydrocarbons species analysed.
PAH no.PAH congenerAmuStructure formulaaVapour pressure (mm Hg 20–25 °C); Log Koc (-) [REF]Classificat-ionbTEFc
  1. PAHs, polycyclic aromatic hydrocarbons.

  2. a

    Chemical structures of PAHs are reproduced from NIST Special Publication 922 on-line internet site.

  3. b

    USEPA, US Environmental Protection Agency [31]: B2, probable human carcinogen; D, not classifiable; IARC, International Agency for Research on Cancer [32]: 2A, probable human carcinogen; 2B, possible human carcinogen; 3, not classifiable.

  4. c

    Toxic equivalence factors (TEFs) from Nisbet and LaGoy [10].

  5. d

    A TEF of 1 is appropriate for high doses, whereas a TEF of 5 is recommended for environmental exposures [10].

  6. N/A, no information available.

1Naphthalene128
thumbnail image
0.082; N/AUSEPA: D0.001
IARC: 3
2Acenaphthalene152
thumbnail image
0.029; 1.40USEPA: D0.001
IARC: N/A
3Acenaphthene154
thumbnail image
4.5 × 10−3; 3.66USEPA: N/A0.001
IARC: N/A
4Fluorene166
thumbnail image
3.2 × 10−4; 3.86USEPA: N/A0.001
IARC: 3
5Phenanthrene178
thumbnail image
6.8 × 10−4; 4.15USEPA: D0.001
IARC: 3
6Anthracene178
thumbnail image
1.7 × 10−5; 4.15USEPA: D0.01
IARC: 3
7Fluoranthene202
thumbnail image
5.0 × 10−6; 4.58USEPA: D0.001
IARC: 3
8Pyrene202
thumbnail image
2.52 × 10−6; 4.58USEPA: D0.001
IARC: 3
9Benzo(a) anthracene228
thumbnail image
2.2 × 10−8; 5.30USEPA: B20.1
IARC: 2A
10Chrysene228
thumbnail image
6.3 × 10−7; 5.30USEPA: B20.01
IARC: 3
11Benzo(b) fluoranthene252
thumbnail image
5.0 × 10−7; 5.74USEPA: B20.1
IARC: 2B
12Benzo(k) fluoranthene252
thumbnail image
9.6 × 10−11; 5.74USEPA: B20.1
IARC: 2B
13Benzo(a)pyrene252
thumbnail image
5.6 × 10−9; 6.74USEPA: B21.0
IARC: 2A
14Indeno(1,2,3-c,d) pyrene276
thumbnail image
~10−11–10−6; 6.20USEPA: B20.1
IARC: 2B
15Benzo(g,h,i) perylene276
thumbnail image
1.0 × 10−10; 6.20USEPA: D0.01
IARC: 3
16Dibenz (a,h) anthracene278
thumbnail image
1.0 × 10−10; 6.52USEPA: B21.0 or 5.0d
IARC: 2A
Detailed polycyclic aromatic hydrocarbon results

The PAH results from the OVS-sampler for individual PVC-carpet tests, expressed as yields, are given in Figure 5(a). The highest yield of total PAHs is produced for under-ventilated conditions. It is clear that the volatile part (adsorbent) of the total mass of PAHs is larger than the particle-associated part (filter). This is true for all combustion conditions investigated.

image

Figure 5. Data from OVS-sampler. Yields of total polycyclic aromatic hydrocarbons from tests with polyvinyl chloride-carpet separated in particle-associated (Filter) and gas-phase (Adsorbent). Note logarithmic scale on y-axis. (a) Actual mass loss yields. (b) Toxicity weighted mass loss yields.

Download figure to PowerPoint

The yields for individual PAHs have been normalised against the TEFs given in Table 5 and are expressed in BaP-TEQ. The normalised (toxicity weighted) yields are shown in Figure 5(b). This changes the distribution pattern between volatile and particle phase. For both well-ventilated and under-ventilated conditions, the toxicity weighted yields for the particle-associated PAHs increases in importance and often dominates over the volatile PAHs. The toxicity weighted yields for the under-ventilated tests are magnitudes higher than those from the well-ventilated tests.

Yield data for individual PAHs is shown in Figure 6. This data is based on sums of filter and adsorbent parts for each PAH. A general trend with decreasing yield for increasing molecular mass is seen for all combustion conditions studied. The data is rather consistent, with reasonable repeatability in distribution pattern between the duplicate samples. It is interesting to note that both well-ventilated (fs2) and under-ventilated (fs3b) combustion of the PVC carpet produces the complete range of PAHs. In the oxidative pyrolysis tests (fs1b), however, only volatile and semi-volatile PAHs are produced (PAHs 1–10).

image

Figure 6. Data from OVS-sampler. Mass loss yields of individual polycyclic aromatic hydrocarbons in the tests with polyvinyl chloride-carpet.

Download figure to PowerPoint

Detailed data on the distribution of individual PAHs between condense phase and gaseous phase for the tests with the PVC carpet are not presented in this paper, but can be found in [15]. A summary of these results is, however, given in what follows.

The distribution of individual PAHs between the condensed phase (filter) and gaseous phase (adsorbent) for the PVC carpet shows that, for the well-ventilated tests, naphthalene, phenanthrene and acenaphthylene (PAH no. 1, 5 and 2, respectively) dominated the gaseous phase, whereas chrysene (PAH no. 10) and other heavier species dominated the condensed phase. The toxicity weighted data was totally dominated by species in the condensed phase including BaP, benzo(a)anthracene and benzo(b)fluoranthene (PAH no. 13, 9 and 11, respectively).

The under-ventilated tests were dominated by naphthalene and phenanthrene (PAH no. 1 and 2, respectively) in the gaseous phase, whereas a range of heavier species (PAH no. 5–13) were present in higher amounts in the condensed phase. The toxicity weighted data was dominated by BaP, benzo(a)anthracene, benzo(b)fluoranthene and dibenzo(ah)anthracene (PAH no. 13, 9, 11 and 16, respectively). These species were present in significant amounts both in filter and adsorbent samples.

In the tests with the wood board, PAH-analysis was made using the OSV-sampler and additionally through analysis of the particle phases separated by the Sioutas impactor.

The results from the OVS-sampler, which are separated in gas phase and particle-associated PAHs, are given in Figure 7(a). The highest yield of total PAHs is clearly seen for under-ventilated conditions where the volatile part of the total PAH is dominating. The yields found from the well-ventilated tests are very low. The measured concentrations in these tests were of the same order of magnitude, but significantly exceeded the concentration of a blank-sample taken between the tests. A single pyrolysis test was analysed for PAH. Only volatile PAHs were found for this combustion condition.

image

Figure 7. Data from OVS-sampler. Yields of total polycyclic aromatic hydrocarbons from tests with the wood board divided in particle-associated (Filter) and gas-phase (Adsorbent). Note logarithmic scale on y-axis. (a) Actual mass loss yields. (b) Toxicity weighted mass loss yields.

Download figure to PowerPoint

Toxicity weighted yields have been calculated and are shown in Figure 7(b). These data show that the particle-associated part of total PAHs dominates the toxicity both for under-ventilated and well-ventilated conditions. The toxicity weighted yields for the under-ventilated tests are several orders of magnitude higher compared with the yields from the well-ventilated tests.

Yield data from the OVS-sampler in tests with the wood board is shown for individual PAHs in Figure 8. The complete range of PAHs is found in the under-ventilated tests, whereas only volatile and semi-volatile PAHs were found in the well-ventilated tests and the pyrolysis test. The repeatability between duplicate tests is acceptable.

image

Figure 8. Data from OVS-sampler. Mass loss yields of individual polycyclic aromatic hydrocarbons in the tests with wood board.

Download figure to PowerPoint

Detailed data on the distribution of individual PAHs between condense phase and gaseous phase for the tests with the wood board are not presented in this paper, but can be found in [15]. A summary of these results is, however, given later.

Data on the distribution of individual PAHs between the condensed phase (filter) and gaseous phase for the tests with the wood board shows that, generally, for the well-ventilated tests, naphthalene (PAH no. 1) dominated in the gaseous phase, whereas phenanthrene (PAH no. 5) dominated in the condensed phase. The toxicity weighted data was dominated by phenanthrene. The under-ventilated tests were dominated by naphthalene and acenaphthylene (PAH no. 1 and 2, respectively) in the gaseous phase, whereas fluoranthene and pyrene (PAH no. 7 and 8, respectively) were present in highest amounts in the condensed phase. The toxicity weighted data was dominated by BaP (PAH no. 13) present predominantly in the condensed phase. The oxidative pyrolysis test only produced PAHs that were found in the gaseous phase of which phenanthrene (PAH no. 5) dominated.

The yield-data of PAHs from analysis of the impactor samples from the Sioutas impactor is presented in Figure 9. The impactor data is presented here as sums of all particle size stages for individual PAHs. The quality of the measurements is to a degree validated by the correlation between the OVS-sampler (Figure 8) and the data from the Sioutas impactor for particle-associated PAHs (Figure 9).

image

Figure 9. Data from analysis of the particles in the impaction plates of the Sioutas impactor. Mass loss yields of individual polycyclic aromatic hydrocarbons in the tests with wood board.

Download figure to PowerPoint

Volatile and semi-volatile PAHs are captured poorly by the impactor sampling as only particulates are sampled. One would therefore expect very low concentrations of those compounds. This is clearly seen in Figure 9, where the data for the under-ventilated tests correlates for particle-associated PAHs between the OVS-sampler, which samples both particle-associated and vapour phase PAHs (Figure 8), and the data from the Sioutas impactor, which only samples particulates (Figure 9). The yield values calculated for the impactor samples are generally somewhat lower compared with the yields from the OVS-sampler. This is expected as the PAHs that vaporise from the particle surfaces are effectively captured by the XAD-2 in the OVS-sampler.

The distribution of individual PAHs between the different particle size stages (impactor plates) from the Sioutas impactor in tests with wood board is shown in the figures hereafter. Figure 10(a) shows an example of typical data from a well-ventilated test. PAHs were, in principal, only found in the <0.25 µm-stage, that is PAHs were only associated to very fine particulates. Only volatile to semi-volatile PAHs were found in low amounts.

Figure 10(b)–(c) shows example of data from an under-ventilated test. Much higher yields of PAHs were found from under-ventilated conditions, and only semi-volatile to non-volatile PAHs are present in significant amounts. Yields are calculated relative to the amount of particulates captured on each stage in Figure 10(b). There is no obvious trend seen in the relative distribution of individual PAHs between particulate size-distribution stages, that is, relatively, there is generally no accumulation of any individual PAH for finer or coarser particulates. However, in absolute terms, the highest amounts of particle-associated PAHs are found with particulates of the smallest sizes, as the <0.25 µm-stage often contains the absolutely highest mass of particulates, which is clear from Figure 10(c), where the yields of individual PAHs are calculated relative to the total amount of particulates captured by the impactor.

image

Figure 10. Yields of individual polycyclic aromatic hydrocarbons relative the amount of soot captured on the different impactor plates for wood board in (a) well-ventilated conditions, (b) and (c) under-ventilated conditions, and (d) pyrolysis conditions.

Download figure to PowerPoint

Figure 10(d) shows data for individual PAHs for the different particle size stages from the Sioutas impactor, in the single pyrolysis test. PAHs were only found from the two stages that captured the largest particulates. These were also the stages that captured the highest masses of particulates (Figure 4). Only semi-volatile PAHs were found.

Summary of total polycyclic aromatic hydrocarbon results

The PAH-analysis was made in selected tests using the OVS-sampler, which consists of a filter that collects particles before the sampled effluent is led through an XAD-2 adsorbent. The sum of the PAHs collected on both the filter (particle-associated) and by the adsorbent (gas phase) is given in Table 6. It is clear from the results that PAHs are predominantly produced during under-ventilated conditions for both materials. However, the yields for under-ventilated conditions are significantly higher than those for the PVC carpet. The yields produced from well-ventilated combustion, and from oxidative pyrolysis, are much lower than those for under-ventilated combustion. Further, for these combustion conditions, it is clear that the PVC carpet produces significantly higher total yields compared with the wood board.

Table 6. Summary of total polycyclic aromatic hydrocarbon results.
Test conditionWood board (OSB)PVC carpet
TestTotal PAH, mass-loss yield (g/kg)TestTotal PAH, mass-loss yield (g/kg)
  1. OSB, oriented strand board; PVC, polyvinyl chloride; PAH, polycyclic aromatic hydrocarbon.

Well-ventilated (fs 2)A0.004A0.050
 B0.004B0.19
Under-ventilated (fs 3b)A4.2A9.0
 B2.7B9.8
Oxidative pyrolysis (fs 1b)A0.007A0.19
 B0.15

Isocyanates

During thermal degradation of PUR, isocyanate monomers are formed together with corresponding amines and amino isocyanates [33]. Low molecular weight isocyanates such as isocyanic acid (ICA) and methyl isocyanate (MIC) are also formed during the thermal degradation of PUR or during thermal degradation of other nitrogen containing polymers, such as different phenol-formaldehyde-urea resins [21, 34]. Other degradation products such as amines, polyols and carbon oxides can additionally be formed. Data on isocyanates are given in Table 7.

Table 7. Data on isocyanates.
IsocyanateAbbreviationsAmuStructure formulaHenry's law constant (atm.m3/mol)
  1. a
  2. b
  3. c
  4. N/A, no information available.

Isocyanic acidICA43.02
thumbnail image
N/A
Methyl isocyanateMIC57.05
thumbnail image
405 (20 °C)a
Ethyl isocyanateEIC71.08
thumbnail image
224 (20 °C)b
Propyl isocyanatePIC85.10
thumbnail image
N/A
Phenyl isocyanatePhI119.12
thumbnail image
1.5 (20 °C)a
Hexamethylene diisocyanateHDI168.20
thumbnail image
0.05 (25 °C)a
2.4-Toluene diisocyanate2.4-TDI174.16
thumbnail image
0.015 (20 °C)a
2.6-Toluene diisocyanate2.6-TDI174.16
thumbnail image
0.015 (20 °C)a
Isophorone diisocyanate 1IPDI 1222.29
thumbnail image
3E−4 (20 °C)a
Isophorone diisocyanate 2IPDI 2222.29
thumbnail image
3E−4 (20 °C)a
4,4′-Methylenediphenyl diisocyanateMDI250.25
thumbnail image
5 E−6 (25 °C)c
Preparatory tests

Both the wood board (OSB) and the PVC carpet emitted isocyanates during thermal degradation prompted using a hot air gun. Isocyanate monomers used in the PUR polymer, MDI for the wood board and hexamethylene diisocyanate (HDI) for the PVC carpet, could be determined together with different kinds of monoisocyanates (Table 8).

Table 8. Pre-tests: indication of isocyanates for the two tested materials.
 ICAMICEICPICPhIHDITDIIPDI 1IPDI 2MDI
  1. ICA, isocyanic acid; MIC, methyl isocyanate; EIC, ethyl isocyanate; PIC, propyl isocyanate; PhI, phenyl isocyanate; HDI, hexamethylene diisocyanate; TDI, toluene diisocyanate; IPDI 1, Isophorone diisocyanate 1; IPDI 2, Isophorone diisocyanate 2; MDI, 4,4′-methylenediphenyl diisocyanate.

PVC carpetXX X XX 
Wood boardXXXXX
Detailed isocyanate results

High concentrations of ICA were determined during the tube furnace tests with the PVC carpet. No HDI could be determined in the mixing chamber (Figure 11(a)). The carpet only contained a relatively small layer of PUR coating, and during the conditions tested, almost all emitted HDI was further degraded.

image

Figure 11. Mass loss yields of isocyanates in tests with (a) polyvinyl chloride-carpet and (b) wood board. Results from sampling and analysis using the dry sampler method.

Download figure to PowerPoint

The tests with wood board, Figure 11(b), showed high concentrations of ICA and MIC and lower concentrations of ethyl isocyanate (EIC), phenyl isocyanate (PhI) and MDI. The results from the tests are consistent with the result from the pre-test. EIC and PhI are a result of thermal decomposition of MDI-based PUR, and the ICA and MIC concentration are produced from thermal decomposition of the urea resin and PUR.

The well-ventilated tests (fs2) resulted in thermal degradation of the material to solely ICA. The pyrolysis tests (fs1) indicated less degradation compared with the well-ventilated tests, which is consistent with the lower temperature found in the pyrolysis test. The under-ventilated tests (fs3b) also exhibited less degradation and, therefore, a higher number of degradation products compared with the tests under well-ventilated conditions. The reason for the less efficient degradation in spite of the higher temperature in the under-ventilated tests must be the high equivalence ratio with a lack of oxygen for oxidation of the material.

Results from the DI method in tests with the wood board indicated that monoisocyanates, such as ICA, MIC and PhI, dominated the isocyanate content in the mixing chamber and were predominately present in the gas phase, that is, they were mainly collected in the denuder part in the denuder–impactor sampler. For ICA, >85% were found in the denuder, for MIC, > 98% and for PhI, > 93%. In addition to the gas phase monoisocyanates, particle bound MDI was determined in impactor stage 1 (d50 = 2.5 µm) during the pyrolysis test. For both sampling occasions using the denuder–impactor sampler (described in Figure 12), the end filter present after the last impactor stage was not analysed. Note that no repetitive tests were made with the DI method and that the results can thus only be regarded as indicative. But the results illustrate the benefit of the method, which is the determination of phase distribution of isocyanates.

image

Figure 12. Distribution of isocyanates between impactor stages of the denuder impactor method from single tests with the wood board (presented as concentration in mixing chamber): (a) an under-ventilated test and (b) a pyrolysis test.

Download figure to PowerPoint

Discussion on isocyanate results

The test scenario used, ISO/TS 19700—the steady-state tube furnace, represents a controlled and constant combustion model. Ideally, once the steady-state period is established, no major disturbances of the combustion taking place in the furnace tube are seen, and the combustion products are effectively diluted and cooled in the mixing chamber where the sampling for analysis takes place. This is intended to enable the analysis of combustion products from isolated and well-defined combustion conditions. However, the variability of a real fire is not captured by this model and it would be interesting, for example, to compare the results on isocyanates from the tube furnace with data from other fire models of different scales.

No prior data are available from measurements on fires where isocyanates are separated into gas phase and particle size distribution stages. There are, however, data available on isocyanates from previous work where fire tests were conducted with the cone calorimeter, ISO 5660 [25]. The cone calorimeter is a small-scale test where the sample material has unlimited access to air for the combustion, that is, the test is inherently well-ventilated. A PVC carpet and a particle board were included in the cone calorimeter study. Note that these products might differ considerably in composition from the products studied in this current project despite their apparent similarity. The results on isocyanates from the cone calorimeter tests are, however, similar to the results from the tube furnace tests in well-ventilated fire stage. In the cone calorimeter, the PVC carpet produced only ICA. The particle board product produced ICA, MIC and MDI, although ICA and MIC dominated and only traces of MDI were found.

In an investigation of a hospital fire [35], a fully furnished room fire test was conducted where the room contained a PUR-mattress and a PVC carpet as part of the fire load. The sampling of smoke gases for isocyanate analysis was divided in three periods, where the last period coincided with flashover and ignition of the PVC carpet. The individual isocyanates found from this sample included ICA, MIC, PHI and traces of TDI, where ICA was the dominating species (>95%).

The distribution of isocyanates in the denuder–impactor sampler has been described previously from exposure chamber studies [19, 23]. Similar to this study, it was observed that during collection of thermal degradation products of PUR, volatile monoisocyanates were collected on the denuder part, whereas diisocyanates were distributed over all the different sampler stages, for example, 4,4-MDI, which is a non-volatile compound, was never present in the vapour phase. Condensation of MDI is fast, and it was instantaneously associated to particles. Immediately after generation, 50% of the MDI was found on the end filter (d50 = 0.5 µm), that is, on the smallest particles.

CONCLUSIONS

  1. Top of page
  2. ABSTRACT
  3. INTRODUCTION
  4. EXPERIMENTAL METHODOLOGY
  5. RESULTS AND DISCUSSION
  6. CONCLUSIONS
  7. ACKNOWLEDGEMENT
  8. REFERENCES

The paper has presented a study of distribution patterns of PAHs and isocyanates between gas phase and particle phase. It has also, in some cases, addressed the question of the distribution of individual particle-associated species between the different size-ranges of particles produced in a fire. The materials studied, PVC carpet and wood board, were chosen on the basis of their prevalence fire exposure scenarios and their chemical composition.

The particle production from these materials varied both with the amounts produced and the particle size distributions. The production of particles on a mass basis was generally significantly lower from the wood board compared with the PVC carpet (approx. 10 times lower), with the exception of the high particle production from oxidative pyrolysis of the wood board.

The tests with the PVC carpet showed that relatively large particles are produced from all combustion conditions examined. The well-ventilated and under-ventilated tests showed production of both large and small particles, whereas the particles from oxidative pyrolysis were found in a narrow distribution of large particle sizes. The tests made with the wood board show preferable predisposition towards the production of small-sized particles during flaming combustion. The difference in particle sizes was not significant between well-ventilated and under ventilated combustion. A significantly different particle size distribution was, however, seen in the tests with oxidative pyrolysis conditions where the maximum in particle mass was found at a larger particle size, and the production of small sized particles was limited.

It was noted that the particle measurements in both tube furnace test-series at two different laboratories gave relatively equivalent results, which indicates that the combustion conditions were equivalent and that the particle analysis was reliable.

The analysis of PAHs in the tests with the PVC carpet showed that volatile PAHs are quantitatively dominating during all types of combustion. However, when the toxicity of the individual species was taken into account, the relative importance between volatile and particle-associated PAHs changed. For both well-ventilated and under ventilated conditions, the toxicity weighted yields for the particle-associated PAHs increased in importance and generally dominated over the volatile species. The toxicity weighted data was dominated by species in the condensed phase including BaP, benzo(a)anthracene and benzo(b)fluoranthene. The toxicity weighted yields for the under ventilated tests were magnitudes higher compared with the yields from the well-ventilated tests. For oxidative pyrolysis conditions, however, the volatile part dominated the toxicity. Regarding the occurrence of individual PAHs, a general trend towards decreasing yields with increasing molecular mass was seen for all combustion conditions studied. It is interesting to note that both well-ventilated and under ventilated combustion of the PVC carpet produced the complete range of PAHs. In the pyrolysis tests, however, only volatile and semi-volatile PAHs were produced.

From the tests with the wood board, it was noted that the highest yields of total PAHs were found from under-ventilated conditions, and the volatile part of the total PAH dominated for this material as well. The yields found from the well-ventilated tests were very low. Toxicity weighted data showed that the particle-associated part dominated the toxicity both for under-ventilated and well-ventilated conditions. The toxicity weighted yields for the under-ventilated tests were several magnitudes higher than those for the well-ventilated tests, and BaP provided the greatest contribution to the toxicity. The complete range of individual PAHs was found in the under-ventilated tests, whereas only volatile and semi-volatile PAHs were found in the well-ventilated tests and the pyrolysis test. The different stages of the impactor were analysed for PAHs in tests with the wood board. PAHs were principally only found associated with very fine particles in well-ventilated tests, and only volatile to semi-volatile PAHs were found in very low concentrations. Much higher yields of PAHs were found in the under-ventilated tests. Only semi-volatile to non-volatile PAHs were present, but in significant amounts. No clear trend was seen in the relative amounts of individual PAHs on the different stages of the impactor, that is, there was no accumulation of any individual PAH for finer or coarser particulates. In absolute terms, however, particle-associated PAHs were found associated with particulates of the smallest sizes as these particles were seen to dominate in general.

Both the PVC carpet and the wood board had low PUR content. This, in combination with the substantial degradation of the PUR in the tests, resulted in no or very small amounts of quantifiable diisocyanates (i.e. high molecular species). Monoisocyanates such as ICA and MIC dominated completely in the emitted degradation products, even during the pyrolysis test. These kinds of monoisocyanates are volatile compounds and almost exclusively present in the gas phase, which was illustrated by the denuder–impactor samples. From the preparatory tests where the conditions were completely different compared with the tube furnace tests, the formation of di-isocyanates compared with mono-isocyanates was much higher. In an actual fire situation, the combustion conditions will vary temporally and spatially depending on the stage of the fire, the ventilation conditions and the material present in the combustion zone. The formation of both mono and diisocyanates at high concentrations will probably be possible during different periods of a fire. However, results from an earlier room fire experiment showed almost exclusively gaseous mono-isocyanates in the fire effluents after flashover, which is the period of a room fire with the highest effluent production rate. More study needs to be performed to determine isocyanate emissions in detail and its contents in different particle size fractions during controlled and actual fire conditions.

ACKNOWLEDGEMENT

  1. Top of page
  2. ABSTRACT
  3. INTRODUCTION
  4. EXPERIMENTAL METHODOLOGY
  5. RESULTS AND DISCUSSION
  6. CONCLUSIONS
  7. ACKNOWLEDGEMENT
  8. REFERENCES

We would like to acknowledge the Swedish Fire Research Board, BRANDFORSK, the joint agency of the Swedish government, local authorities, insurance companies and industry, as being the major sponsor of this project.

REFERENCES

  1. Top of page
  2. ABSTRACT
  3. INTRODUCTION
  4. EXPERIMENTAL METHODOLOGY
  5. RESULTS AND DISCUSSION
  6. CONCLUSIONS
  7. ACKNOWLEDGEMENT
  8. REFERENCES
  • 1
    Stec A, Hull R. Introduction to fire toxicity. In Fire Toxicity, Stec A, Hull R (eds). Woodhead Publishing Limited: Cambridge, 2010.
  • 2
    Hertzberg T, Blomqvist P. Particles from fires—a screening of common materials found in buildings. Fire and Materials 2003; 27:295314.
  • 3
    Rhodes J, Smith C, Stec AA. Characterisation of soot particulates from fire retarded and nanocomposite materials. Polymer Degradation and Stability 2011; 96:277284.
  • 4
    D'Alessio A, D'Anna A, Gambi G, Minutolo P, Sgro LA, Violo A. Combustion-generated nanoparticles. La Chimica e l'Industria 1999; 81:10011006.
  • 5
    Wichmann H-E, et al. Daily mortality and fine and ultrafine particles in Erfurt, germany. Part I: role of particle number and particle mass. Health Effects Institute, 2000.
  • 6
    Johnston CJ, Finkelstein JN, Mercer P, Corson N, Gelein R, Oberdorster G. Pulmonary effects induced by ultrafine PTFE particles. Toxicology and Applied Pharmacology 2000; 168(3):20815.
  • 7
    Levin BC, Kuligowski ED. Toxicology of fire and smoke. In Inhalation Toxicology, Salem H, Katz SA (eds). CRC Press (Taylor and Francis Group): Boca Raton, FL, USA, 2005; 205228.
  • 8
    Frank R. SO2-particulate interactions: recent observations. Ammerican Journal of Industrial Medicine 1980; 1(3–4):42734.
  • 9
    Blomqvist P. Emissions from fires: consequences for human safety and the environment. In Fire Technology. Lund University: Lund, 2005.
  • 10
    Nisbet ICT, LaGoy PK. Toxic equivalence factors (TEFs) for polycyclic aromatic hydrocarbon (PAHs). Regulatory Toxicology and Pharmacology 1992; 16:290300.
  • 11
    Ott MG, Diller WF, Jolly AT. Respiratory effects of toluene diisocyanate in the workplace: a discussion of exposure–response relationships. Critical Reviews in Toxicology 2003; 33(1):159.
  • 12
    Baur X, Marek W, Ammon J, Czuppon AB, Marczynski B, Raulf-Heimsoth M, Roemmelt H, Fruhmann G. Respiratory and other hazards of isocyanates. International Archives of Occupational and Environmental Health 1994; 66:141152.
  • 13
    ISO/TS 19700:2007, controlled equivalence ratio method for the determination of hazardous components of fire effluents, ISO, 2007.
  • 14
    Stec AA, Hull TR, Lebek K. Characterisation of the steady state tube furnace (ISO TS 19700) for fire toxicity assessments. Polymer Degradation and Stability 2008; 93:20582056.
  • 15
    Blomqvist P, McNamee MS, Stec AA, Gylestam D, Karlsson D. Characterisation of fire generated particles, 2010:01, Borås, 2010.
  • 16
    Hertzberg T, Blomqvist P, Dalene M, Skarping G. Particles and isocyanates from fires, SP Swedish National Testing and Research Institute, 2003:05, Borås, 2003.
  • 17
    Stec AA, Hull TR, Lebek K, Purser JA, Purser DA. The effect of temperature and ventilation conditions on the toxic product yields from burning polymers. Fire and Materials 2008; 32:4960.
  • 18
    ISO 19706:2007, guidelines for assessing the fire threat to people, ISO, 2007.
  • 19
    Dahlin J, Spanne M, Karlsson D, Dalene M, Skarping G. Size-separated sampling and analysis of isocyanates in workplace aerosols. Part I. Denuder-cascade impactor sampler. Annals of Occupational Hygiene 2008; 52(5):361374.
  • 20
    Karlsson D, Dahlin J, Marand Å, Skarping G, Dalene M. Determination of airborne isocyanates as di-n-butylamine derivatives using liquid chromatography and tandem mass spectrometry. Analytica Chimica Acta 2005; 534:263269.
  • 21
    Karlsson D, Spanne M, Dalene M, Skarping G. Airborne thermal degradation products of polyurethane coatings in car repair shops. Journal of Environmental Monitoring 2000; 2:462469.
  • 22
    Marand Å, Karlsson D, Dalene M, Skarping G. Solvent-free sampling with di-n-butylamine for monitoring of isocyanates in air. Journal of Environmental Monitoring 2005; 7:335343.
  • 23
    Dahlin J, Spanne M, Dalene M, Karlsson D, Skarping G. Size-separated sampling and analysis of isocyanates in workplace aerosols—part II: aging of aerosols from thermal degradation of polyurethane. Annals of Occupational Hygiene 2008; 52(5):375383.
  • 24
    Butler KM, Mulholland GW. Generation and transport of smoke components. Fire Technology 2004; 40(2):149176.
  • 25
    ISO 5660-1, fire tests—reaction to fire—part 1: rate of heat release from building products (cone calorimetric method), ISO, ISO 5660-1:1993, 1993.
  • 26
    Hull TR, Paul KT. Bench-scale assesment of combustion toxicity—a critical analysis of current protocols. Fire Safety Journal 2007; 42(5):340365.
  • 27
    Delistraty D. Toxic equivalency factor approach for risk assessment of polycyclic aromatic hydrocarbons. Toxicological and Environmental Chemistry 1997; 64:81108.
  • 28
    Manahan SE. Environmental Chemistry (6th edn). Lewis Publishers: Boca Raton, Florida, USA, 1994.
  • 29
    Baek SO, Goldstone ME, Kirk PWW, Lester JN, Perry R. Phase distribution and particle size dependency of polycyclic aromatic hydrocarbons in the urban atmosphere. Chemosphere 1991; 22(5–6):503520.
  • 30
    U.S. Department Of_Health and Human Services. Toxicological profile for polycyclic aromatic hydrocarbons, U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES, Public Health Service, Agency for Toxic Substances and Disease Registry, 1995.
  • 31
    EPA. Integrated risk information system (IRIS). chemical specific reference doses and cancer potency factors. Environmental Protection Agency, Cincinnatti, USA, 2005.
  • 32
    IARC. IARC monographs on the evaluation of carcinogenic risks to humans. IARC International Agency for Reserch on Cancer, 2005.
  • 33
    Karlsson D, Dalene M, Skarping G, Marand Å. Determination of isocyanate acid in air. Journal of Environmental Monitoring 2001; 3:432436.
  • 34
    Karlsson D, Dalene M, Skarping G. Determination of complex mixtures of airborne isocyanates and amines. Part 5. Determination of low molecular weight aliphatic isocyanates as dibutylamine derivatives. Analyst 1998; 123:15071512.
  • 35
    Hertzberg T, Blomqvist P, Tuovinen H. Reconstruction of an arson hospital fire. Fire and Materials 2007; 31:225240.