Air pollutant sources and exposure: Organic tracers for source identification of exposure to fine particles and effects of plug-in hybrid electric vehicles on ozone concentrations in Colorado.

摘要

Premature mortality has been correlated with ambient concentrations of air pollutants including fine particulate matter (PM2.5) and ozone. The research described in this dissertation has focused on several aspects of the emission source to human exposure chain for these two air pollutants.;The first two projects included in this dissertation demonstrate the feasibility and importance of including organic tracer species in receptor modeling for source apportionment of PM2.5 exposure concentrations. First, specified source profiles, contributions, and uncertainties were used to generate synthetic PM2.5 exposure data. Positive Matrix Factorization was applied to these data; the resulting source contributions and profiles were compared to the known inputs. Sources with unique tracer species were typically modeled well. Next, a pilot study gathered 64 24-hour PM2.5 exposure samples for a convenient population of subjects living in or near Boulder, CO. The samples were analyzed for PM2.5 mass, elemental and organic carbon, organic compounds, water-soluble metals, ammonia, and nitrate. Fifty-four organic species had signal-to-noise ratios larger than two; these included tracer species that helped identify meat cooking, biomass, gasoline, cigarette smoke, and motor oil combustion. Soil and brake dust were identified using inorganic markers.;The third project explored the effects of plug-in hybrid electric vehicles (PHEVs) on ozone concentrations in the Denver area. For several hypothetical scenarios, a unit commitment and dispatch model was used to estimate the charging patterns of PHEVs and the power plants dispatched to provide their electricity. The CAMx atmospheric chemistry and transport model was used to simulate the effects of resulting emissions changes on ozone concentrations. Modeled peak ozone concentrations were typically reduced by up to 3 ppb in the 100% PHEV penetration case. Ozone concentration increases were projected for small areas near central Denver. Overall reductions in ozone were relatively modest, as emissions from outside Colorado contribute significantly to ozone in the Denver metropolitan area.