Environmental sampling of volatile organic compounds during the 2018 Camp Fire in Northern California

Trace analysis of volatile organic compounds(VOCs) during wildfires is imperative for environmental and health risk assessment. The use of gas sampling devices mounted on unmanned aerial vehicles(UAVs) to chemically sample air during wildfires is of great interest because these devices move freely about their environment, allowing for more representative air samples and the ability to sample areas dangerous or unreachable by humans. This work presents chemical data from air samples obtained in Davis, CA during the most destructive wildfire in California's history-the 2018 Camp Fire – as well as the deployment of our sampling device during a controlled experimental fire while fixed to a UAV. The sampling mechanism was an in-house manufactured micro-gas preconcentrator(μPC) embedded onto a compact battery-operated sampler that was returned to the laboratory for chemical analysis. Compounds commonly observed in wildfires were detected during the Camp Fire using gas chromatography mass spectrometry(GC–MS), including BTEX(benzene, toluene, ethylbenzene, m + p-xylene, and o-xylene), benzaldehyde, 1,4-dichlorobenzene, naphthalene, 1,2,3-trimethylbenzene and 1-ethyl-3-methylbenzene. Concentrations of BTEX were calculated and we observed that benzene and toluene were highest with average concentrations of 4.7 and 15.1 μg/m^(3), respectively. Numerous fire-related compounds including BTEX and aldehydes such as octanal and nonanal were detected upon experimental fire ignition, even at a much smaller sampling time compared to samples taken during the Camp Fire. Analysis of the air samples taken both stationary during the Camp Fire and mobile during an experimental fire show the successful operation of our sampler in a fire environment.

On-road emissions of CO,CO2 and NOx from four wheeler and emission estimates for Delhi

This study presents the emission factor of gaseous pollutants （CO, CO2, and NOx） from on-road tailpipe measurement of 14 passenger cars of different types of fuel and vintage. The trolley equipped with stainless steel duct, vane probe velocity meter, flue gas analyzer, Nondispersive infra red （NDIR） C02 analyzer, temperature, and relative humidity （RH） sensors was connected to the vehicle using a towing system. Lower CO and higher NOx emissions were observed from new diesel cars （post 2010） compared to old cars （post 2005）, which implied that new technological advancement in diesel fueled passenger cars to reduce CO emission is a successful venture, however, the use of turbo charger in diesel cars to achieve high temperature combustion might have resulted in increased NOx emissions. Based on the measured emission factors （g/kg0, and fuel consumption （kg）, the average and 95% confidence interval （CI） bound estimates of CO, CO2, and NOx from four wheeler （4W） in Delhi for the year 2012 were 15.7 （1.4-37.1）, 6234 （386-12,252）, and 30.4 （0.0-103） Gg/year, respectively. The contribution of diesel, gasoline and compressed natural gas （CNG） to total CO, C02 and NOx emissions were 7：84：9, 50：48：2 and 58：41：1 respectively. The present work indicated that the age and the maintenance of vehicle both are important factors in emission assessment therefore, more systematic repetitive measurements coveting wide range of vehicles of different age groups, engine capacity, and maintenance level is needed for refining the emission factors with CI.