Sahu M.,Aerosol and Air Quality Research Laboratory |
Hu S.,Aerosol and Air Quality Research Laboratory |
Ryan P.H.,University of Cincinnati |
Le Masters G.,University of Cincinnati |
And 3 more authors.
Science of the Total Environment | Year: 2011
Exposure to traffic-related pollution during childhood has been associsated with asthma exacerbation, and asthma incidence. The objective of the Cincinnati Childhood Allergy and Air Pollution Study (CCAAPS) is to determine if the development of allergic and respiratory disease is associated with exposure to diesel engine exhaust particles. A detailed receptor model analyses was undertaken by applying positive matrix factorization (PMF) and UNMIX receptor models to two PM2.5 data sets: one consisting of two carbon fractions and the other of eight temperature-resolved carbon fractions. Based on the source profiles resolved from the analyses, markers of traffic-related air pollution were estimated: the elemental carbon attributed to traffic (ECAT) and elemental carbon attributed to diesel vehicle emission (ECAD). Application of UNMIX to the two data sets generated four source factors: combustion related sulfate, traffic, metal processing and soil/crustal. The PMF application generated six source factors derived from analyzing two carbon fractions and seven factors from temperature-resolved eight carbon fractions. The source factors (with source contribution estimates by mass concentrations in parentheses) are: combustion sulfate (46.8%), vegetative burning (15.8%), secondary sulfate (12.9%), diesel vehicle emission (10.9%), metal processing (7.5%), gasoline vehicle emission (5.6%) and soil/crustal (0.7%). Diesel and gasoline vehicle emission sources were separated using eight temperature-resolved organic and elemental carbon fractions. Application of PMF to both datasets also differentiated the sulfate rich source from the vegetative burning source, which are combined in a single factor by UNMIX modeling. Calculated ECAT and ECAD values at different locations indicated that traffic source impacts depend on factors such as traffic volumes, meteorological parameters, and the mode of vehicle operation apart from the proximity of the sites to highways. The difference in ECAT and ECAD, however, was less than one standard deviation. Thus, a cost benefit consideration should be used when deciding on the benefits of an eight or two carbon approach.
Fang J.,Aerosol and Air Quality Research Laboratory |
Leavey A.,Aerosol and Air Quality Research Laboratory |
Biswas P.,Washington University in St. Louis
Fuel | Year: 2014
A methane-air flat flame reactor was designed to study the initial stages of combustion through flash pyrolysis of biomass and factors contributing to particulate emissions were examined. Six different types of biomass, Prosopis juliflora, cotton stalk, poplar, applewood, oak, and cherry wood were pyrolysed in a methane-air flat flame at various moisture contents. Particulate matter formed was characterized through measuring mass, and particle number size distributions. The moisture content of biomass feed stock was varied from 0% to 20%, while the particle feed sizes were maintained at 105 μm or below, to limit heat transfer effects in the particle. Thermo-gravimetric analysis was also conducted on the biomass to obtain mass fraction data (% volatiles, moisture content) along with kinetic data. Results indicated that the presence of moisture causes a delay in devolatilization thus decreasing the overall efficiency in combustion. The results from this study can be used to optimize biomass combustion for use as fuel in household settings to minimize negative impacts due to poor air quality. © 2013 Elsevier Ltd. All rights reserved.