Understanding airborne contaminants produced by different fuel packages during training fires

Figures & data

Table 1. Summary of area air sampling methods.

Sampling performed^A	Scenario^B	n	Duration of scenario (min)	Sampling time during scenario (min)^C	Method
Acid gases: hydrogen bromide, hydrogen fluoride, hydrogen chloride, phosphoric acid	Pallet and straw	6	26–30	23–30	Silica gel tube (Supelco ORBO 53), 500 mL/min, analyzed by ion chromatography (NIOSH method 7903)
	Alpha OSB	3	25–28	12–26
	Bravo OSB	3	25–31	7–33
Aldehydes: acetaldehyde, acrolein, formaldehyde	Pallet and straw	6	26–30	24–31	XAD-2 tube (SKC 226-117), 200 mL/min, analyzed by GC/NPD (OSHA method 52)
	Alpha OSB	3	25–28	16–29
	Bravo OSB	3	25–31	15–41
	Simulated smoke	6	22–31	20–32
Isocyanates: methyl isocyanate, methylene diphenyl diisocyanate (MDI), phenyl isocyanate	Alpha OSB	3	25–28	9–25	Asset denuder sampler (Supleco EZ4), 200 mL/min, analyzed by LC/MS/MS (ISO method 17734)
	Bravo OSB	3	25–31	12–45
VOCs: 64 compounds	Pallet and straw	4	26–30	∼15	6 L evacuated canister with 15-min regulator and fritted pre-filter, analyzed by GC/MS (EPA method TO-15)
	Downwind	4		∼15
	Alpha OSB	2	25–28	∼15
	Downwind	2		∼15
	Bravo OSB	2	25–31	∼15
	Downwind	2		∼15
	Simulated smoke	4	22–31	∼15
Respirable particles (downwind only)	Pallet and straw	6	26–30	22–28	Aluminum cyclone (SKC 225-01-02), tared PVC, 2.5 L/min, analyzed gravimetrically, 50% cut-point of 4 µm
	Alpha OSB	2	25–28	25–29
	Bravo OSB	3	25–31	21–25

GC/NPD = gas chromatography/nitrogen phosphorous detector; LC/MS/MS = liquid chromatography/tandem mass spectrometry; GC/MS = gas chromatography/mass spectrometry; VOCs = volatile organic compounds; MDI = methylene diphenyl diisocyanate.

^AArea air samples were also collected for PAHs, BTEX, and HCN during the simulated smoke exercises by placing samplers inside the training structure using the same methodology as for personal air sampling (n = 6 for each analyte).

^BOSB scenarios also included two pallets and one bale of straw. Pallet and straw scenarios included three pallets and one bale of straw.

^COccasionally, sampling time was less than the duration of the scenario because of pump faults due to extreme conditions. Sampling times higher than the scenario duration were due to a delay in turning off the sampling pumps.

Table 2. Summary of personal air concentrations by type of participant and fuel package.

Analytes	Type of participant	Type of Fuel Package/Job Assignment^B	N	ND (%)	Median	Range	P-value firefighter vs. instructor	P-value alpha OSB vs. bravo OSB
	Instructor	Pallet and straw	28	0	0.608	0.0913–2.31	<0.01
	Firefighter		19	0	2.240	0.691–6.96
HCN (ppm)	Instructor	Alpha OSB	12	0	0.376	0.154–1.760	0.06	0.57
	Firefighter		9	0	0.830	0.137–2.02
	Instructor	Bravo OSB	11	0	0.457	0.270–0.882	0.02
	Firefighter		6	0	0.889	0.645–1.29
Residential Fire Study HCN (ppm)^A	N/A	Attack	13	0	33.5	4.10–100	N/A	N/A
	N/A	Search	17	29	0.085	<0.060–106	N/A
Total PAHs (mg/m^3)	Instructor	Pallet and straw	17	0	2.78	1.23–6.89	0.02
	Firefighter		9	0	3.39	2.27–18.10
	Instructor	Alpha OSB	9	0	4.44	1.77– 9.21	0.07	<0.01
	Firefighter		5	0	8.33	4.95–29.9
	Instructor	Bravo OSB	9	0	14.2	3.21–19.9	<0.01
	Firefighter		6	0	34.0	22.2–56.4
Residential Fire Study total PAHs (mg/m^3)^A	N/A	Attack	19	0	23.8	7.46–78.2	N/A	N/A
	N/A	Search	16	0	17.8	9.77–43.8	N/A
Benzene (ppm)	Instructor	Pallet and straw	28	0	3.00	1.09–7.10	<0.01
	Firefighter		20	0	4.18	2.33–11.9
	Instructor	Alpha OSB	12	0	4.01	0.470–12.1	0.02	<0.01
	Firefighter		11	0	7.30	2.93–25.6
	Instructor	Bravo OSB	12	0	9.09	5.25–26.2	<0.01
	Firefighter		10	0	31.7	18.1–54.9
Residential Fire Study benzene (ppm)^A	N/A	Attack	17	0	40.3	12.4–322	N/A	N/A
	N/A	Search	22	0	37.9	12.0–306

^AResults from Fent et al.^[13] were provided for comparison.

^BWe stratified by fuel package in the current study and job assignment in the previous study. OSB scenarios also included two pallets and one bale of straw. Pallet and straw scenarios included three pallets and one bale of straw.

^CMost protective short-term occupational exposure limit for: HCN NIOSH STEL (4.700 ppm), Total PAHs ACGIH excursion limit for coal-tar pitch volatiles (1 mg/m³), and Benzene NIOSH STEL (1.000 ppm).

Table 3. Area air concentrations of acid gases inside structure by type of fuel package.

Acid gases^A	Type of fuel package^B	n	ND (%)	Median	Range	P-value Pallet and Straw vs. Alpha OSB vs. Bravo OSB	Most protective short-term occupational exposure limit^C
Hydrogen Fluoride (mg/m^3)	Pallet and Straw	6	0	3.84	2.97–4.72	0.01	ACGIH C: 2.00 (mg/m^3)
	Alpha OSB	3	0	1.03	0.766–1.06
	Bravo OSB	3	0	1.93	0.500–2.31
Hydrogen Chloride (mg/m^3)	Pallet and Straw	6	0	8.74	7.15–12.6	0.04	ACGIH C: 2.00 (mg/m^3)
	Alpha OSB	3	0	4.60	3.93–9.10
	Bravo OSB	3	33	1.26	<0.550–6.260

^AHydrogen bromide (<0.826 mg/m³) and Phosphoric acid (<0.551 mg/m³) were non-detect for all samples.

^BSimulated smoke acid gas results (<0.175 mg/m³) were non-detect for all samples. OSB scenarios also included two pallets and one bale of straw. Pallet and straw scenarios included three pallets and one bale of straw.

^CBased on review of short-term exposure limits (STELs) or ceiling limits (C) as listed with NIOSH Recommended Exposure Limits, Occupational Safety and Health Administrations (OSHA) Permissible Exposure Limits, and or ACGIH Threshold Limit Values (TLVs)^®. If no STEL or C exists, ACGIH excursion limits (5x the TLV) are provided.

Table 4. Area air concentrations of aldehyde and isocyanates inside structure by type of fuel package.

Aldehydes	Type of fuel package^A	n	ND (%)	Median	Range	P-value pallet and straw vs. Alpha OSB vs. Bravo OSB	Most protective short-term occupational exposure limit^B
Acetaldehyde (mg/m^3)	Pallet and Straw	6	0	79.3	51.5–135	0.03	ACGIH C: 45.0 mg/m^3
	Alpha OSB	3	0	60.7	48.0–77.6
	Bravo OSB	3	0	291	180–419
	Simulated smoke	6	83	<0.154	<0.137–0.620
Acrolein (mg/m^3)	Pallet and Straw	6	0	5.38	3.53–7.24	0.03	ACGIH C: 0.230 mg/m^3
	Alpha OSB	3	0	4.85	3.60–4.97
	Bravo OSB	3	0	60.6	10.5–71.6
	Simulated smoke	6	100	<0.497	<0.458–0.732
Formaldehyde (mg/m^3)	Pallet and Straw	6	0	4.61	2.89–5.59	0.04	NIOSH C: 0.123 mg/m^3
	Alpha OSB	3	0	4.45	3.77–6.52
	Bravo OSB	3	0	35.2	13.1–36.7
	Simulated smoke	6	100	<0.133	<0.122–0.195
Isocyanates	Type of fuel package	n	ND (%)	Median	Range	P-value pallet and straw vs. Alpha OSB vs. Bravo OSB	Most protective short-term occupational exposure limit
Methyl Isocyanate (µg/m^3)	Alpha OSB	3	0	20.5	11.8–52.7	0.83	ACGIH EL: 230 µg/m^3
	Bravo OSB	3	0	35.0	10.9–166
MDI (µg/m^3)	Alpha OSB	3	100	<0.051	<0.041–0.113	0.51	NIOSH C: 200 µg/m^3
	Bravo OSB	3	0	0.273	0.031–0.831
Phenyl Isocyanate (µg/m^3)	Alpha OSB	3	33	<0.034	<0.015–0.041	0.83	NA
	Bravo OSB	3	0	0.033	0.019–0.120

^AOSB scenarios also included two pallets and one bale of straw. Pallet and straw scenarios included three pallets and one bale of straw.

^BBased on review of short-term exposure limits (STELs) or ceiling limits (C) as listed with NIOSH Recommended Exposure Limits, Occupational Safety and Health Administrations (OSHA) Permissible Exposure Limits, and or ACGIH Threshold Limit Values (TLVs). If no STEL or C exists, ACGIH excursion limits (EL, 5x the TLV) are provided.

Figure 1. VOCs (ppm) area air concentrations inside structure by type of fuel package: pallet and straw (n = 4), Alpha OSB (n = 2), and Bravo OSB (n = 2). OSB scenarios also included two pallets and one bale of straw. Pallet and straw scenarios included three pallets and one bale of straw. The box and whiskers provide the minimum, 25^th percentile, median, 75^th percentile, and maximum values.

Table 5. VOCs air concentrations by location and type of fuel package.

VOCs	Fuel Type^B	Location	n	ND (%)	Median	Range
Benzene^A (ppm)	Pallet and Straw	Downwind	4	0	0.0033	0.000980–0.013
		Background	2	100	<0.000354	<0.000354
		Inside Structure	4	0	1.30	0.900–1.40
	Bravo OSB	Background	1	100	<0.000354	<0.000354
		Downwind	2	0	0.0665	0.041–0.092
		Inside Structure	2	0	2.57	0.049–5.10
	Alpha OSB	Background	1	0	0.00059	0.00059
		Downwind	2	0	0.0139	0.0098–0.018
		Inside Structure	2	0	0.0139	0.420–4.200
	Simulated Smoke	Background	2	50	0.000477	<0.000354–0.000600
		Inside Structure	4	50	0.000877	<0.000354–0.0021

^ABenzene NIOSH STEL: 1.00 ppm

^BOSB scenarios also included two pallets and one bale of straw. Pallet and straw scenarios included three pallets and one bale of straw.

Figure 2. Downwind area air concentrations (mg/m³) of respirable particles by type of fuel package. All background samples were non-detect. The box and whiskers provide the minimum, 25^th percentile, median, 75^th percentile, and maximum values.

Fent, K.W., D. Evans, K. Babik, C. Striley, S. Bertke, et al.: Airborne contaminants during controlled residential fires. J. Occup. Environ. Hyg. 15(5):399–412 (2018).

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