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ABSTRACT A system has been developed to combine remote sensing and ground-based measurements of aerosol concentration and aerosol light scattering parameters into a three-dimensional view of the atmosphere over the [...]

Optimal use of Hierarchical Bayesian Model (HBM)-assembled aerosol optical depth (AOD)-PM2.5 fused surfaces in epidemiologic studies requires homogeneous temporal and spatial fused surfaces. No analytical method is available to evaluate spatial heterogeneity. The temporal case-crossover design was modified to assess the spatial association between four experimental AOD-PM2.5 fused surfaces and four respiratory–cardiovascular hospital events in 12 km2 grids. The maximum number of adjacent lag grids with significant odds ratios (ORs) identified homogeneous spatial areas (HOSAs). The largest HOSA included five grids (lag grids 04; 720 km2) and the smallest HOSA contained two grids (lag grids 01; 288 km2). Emergency department asthma and inpatient asthma, myocardial infarction, and heart failure ORs were significantly higher in rural grids without air monitors than in urban grids with air monitors at lag grids 0, 1, and 01. Rural grids had higher AOD-PM2.5 concentration levels, population density, and poverty percentages than urban grids. Warm season ORs were significantly higher than cold season ORs for all health outcomes at lag grids 0, 1, 01, and 04. The possibility of elevated fine and ultrafine PM and other demographic and environmental risk factors synergistically contributing to elevated respiratory–cardiovascular chronic diseases in persons residing in rural areas was discussed. [ABSTRACT FROM AUTHOR]

The heterogeneous reactions of HOBr with ice surfaces formed by freezing sodium halide solutions are studied using a coated-wall, low-pressure flow tube coupled to a quadrupole mass spectrometer. It is found that compared to analogous reactions with HOCl, HOBr reactions are slower than expected with a maximum uptake coefficient of approximately 0.01.

A study is conducted to evaluate the relative importance of different heterogeneous mechanisms that may release gas-phase Br2 into the Arctic boundary layer with the help of interactions of Cl2, HOCl and BrCl with halide-containing ice surfaces. The impact of Cl2, HOCl, and BrCl heterogenous chemistry on catalytic ozone destruction in the Artic boundary layer is discussed.