Establishing a novel combustion generator system to simulate and study emissions from diverse applications.

Abstract

Inhalation of emissions from combustion events such as military burn pits and wildland-urban interface fires result in exposures to complex aerosols that may cause adverse health effects. A surrogate combustion generator was created to study these events. A pellet stove was modified to burn diverse fuels comprised of materials found in burn pits (plastic, rubber, and wood). Jet fuel (JF) was added during combustion. The purpose of this project was to: 1) operate the generator over diverse parameters; and 2) characterize the resultant emissions. Pellet combustion (8 g/minute; range: 1-34) ± JF (0.2 mL/minute; range: 0-1) was conducted at fixed rates. Real-time and off-line aerosol characterizations (size distributions, concentrations, morphology) and chemical measures (total and speciation of volatiles, organics, elementals) with subsequent analytic methodology were performed. Pellet combustion produced an average particle concentration of 7.0e+6±1.1e+6 #/cc, and a total volatile organic compound concentration (TVOC) of 0.97+0.41 parts per million (PPM). The addition of JF accelerated the combustion process and increased the total particle counts to 4.5e+7±8.3e+6 #/cc, but decreased the TVOC to 0.63±0.26 ppm. Ultrafine particles were predominantly generated with similar count median diameters (<100 nm) and polydisperse distributions (GSD>1.5). Chemical speciation revealed potential human carcinogens (formaldehyde, acetaldehyde) and the addition of JF resulted in a >40-fold drop in organic carbon constituents. Adding plastic and rubber into the pellet mixture resulted in emissions containing 4% methyl-methacrylate and 10% methyl-isobutyl-ketones. Future experiments will assess diverse wood varieties, synthetic building constituents, and asses the biological effects that follow these inhalation exposures.