Measurement of short-lived reactive species and long-lived free radicals in air samples from structural fires.
Jankovic J; Jones W; Castranova V; Dalal N
Appl Occup Environ Hyg 1993 Jul; 8(7):650-654
Short lived reactive species and long lived free radicals were measured in air samples from structural fires using chemiluminescence (CL) and electron spin resonance (ESR). Laboratory trials were first conducted to determine the feasibility of monitoring the generation of reactive species from fire smoke using the CL method. Lumino was chosen to enhance the chemiluminescent signal. Test fires used burning mixtures of paper, cloth, and wood in a confined container with a fume hood. Samples were collected on impingers and on polyvinyl-chloride (PVC) filters. The time courses for CL generated from filter or impinger samples were highest immediately after sampling and rapidly declined with time, as would be expected with short lived reactive species. CL from smoke samples remained elevated for as long as 22 hours (hr) after sampling, with half time for decay to the 22hr level being 4 minutes (min) for impinger samples. CL from impinger samples were about three times higher than from filter samples. There was no relationship between visible smoke and CL, indicating that the absence of visible smoke was not sufficient to indicate a nontoxic environment. PVC filters worn by fire fighters at structural fires were divided for CL and ESR monitoring. The overall top to bottom vertical height of a given spectrum provided a relative measure of the free radical content of the sample. The ESR clearly showed that the long lived radicals correlated with the amount of visible smoke at the time of aerosol collection. The visual darkness of the aerosol on a filter correlated positively with the strength of the ESR peak. The authors conclude that short lived radicals appear to be detected by the CL technique and are not related to visible smoke, while long lived radicals are detected by ESR and their signal magnitudes are dependent on the intensity of the smoke.
NIOSH-Author; Air-quality-monitoring; Combustion-products; Firemen; Occupational-exposure; Free-radicals; Fire-fighting
Applied Occupational and Environmental Hygiene