Characterization of Woodsmoke Generated in the Air Pollution Exposure Lab and Comparison to Diesel Exhaust

Abstract

To address the increasing concern of woodsmoke (WS) and better understand its effects on human health, a woodsmoke generation system was built in the Air Pollution Exposure Laboratory to facilitate future controlled human exposure studies. Two different woodsmoke conditions, flaming (WSFL) and smoldering (WSSM), were generated, and PM2.5 concentrations of approximately 500 g/m3 were achieved. The woodsmoke produced using the system was characterized in this study and compared with diesel exhaust (DE) generated and collected at the same facility. Within the gas phase generated by the pollutants, WS showed slight increases in CO and CO2 compared to filtered air (FA), while DE contained significantly higher levels of NOx, CO2, and total volatile organic compounds compared to FA. The WS aerosols were comprised of approximately 98% organics, 0.6% NH4, 0.9% NO3, and 0.2% SO4. Among the organic species, the CHO1 and CHOgt1 families encompassed around 60%, which was higher than the fraction of oxygenated families in DE aerosols. Moreover, the WS aerosols had higher concentrations of Cd compared to the DE aerosols. Greater oxidative potentials were also observed for WSFL and WSSM compared to DE, with DTT consumption rates normalized to the PM mass being 0.0099 and 0.0090 nmol/min/g, respectively. The difference in the compositions and properties of WS and DE suggests that it is critical to conduct further studies on how these pollutants can affect health differently.