Global Health and Climate Effects of Organic Aerosols from Different Sources

Abstract

The impact of aerosols on human health and climate is well-recognized, yet many studies have only focused on total PM2.5 or changes from anthropogenic activities. This study quantifies the health and climate effects of organic aerosols (OA) from anthropogenic, biomass burning, and biogenic sources. Using two atmospheric chemistry models, CAM-chem and GEOS-Chem, our findings reveal that anthropogenic primary OA (POA) has the highest efficiency for health effects but the lowest for direct radiative effects due to spatial and temporal variations associated with population and surface albedo. The treatment of POA as nonvolatile or semivolatile also influences these efficiencies through different chemical processes. Biogenic OA shows moderate efficiency for health effects and the highest for direct radiative effects but has the lowest efficiency for indirect effects due to the reduced high cloud, caused by stabilized temperature profiles from aerosol–radiation interactions in biogenic OA-rich regions. Biomass burning OA is important for cloud radiative effect changes in remote atmospheres due to its ability to be transported further than other OAs. This study highlights the importance of not only OA characteristics such as toxicity and refractive index but also atmospheric processes such as transport and chemistry in determining health and climate impact efficiencies.

Secondary Organic Aerosol Formation from the OH Oxidation of Phenol, Catechol, Styrene, Furfural, and Methyl Furfural

“…To accurately encapsulate the large OA range found during the wildfire aging process, a volatility basis set (VBS) is used to represent SVOCs and IVOCs at wildfire-relevant OA. These values have not been previously reported for the species studied here, despite VBSs being the most common method for representing SOA in modern large-scale models. − In addition, none of those studies corrected their results for vapor wall loss (VWL) to chamber walls, which has been shown to have an important impact on SOA yields. ,− …”

Effect of Relative Humidity on the Rate of New Particle Formation for Different VOCs

“…Understanding the chemical and physical properties of atmospheric aerosols is critical to interpreting their direct and indirect impacts on climate change, such as by scattering and absorbing solar radiation and impacting cloud formation [1][2][3][4][5]. Organic aerosol (OA) accounts for up to 90% of Earth's total aerosol mass budget [6][7][8], with secondary organic aerosol (SOA) making up 70-90% of OA fine particle mass [9,10].…”