Optical and chemical characteristics of the atmospheric aerosol in four towns in southern Poland.

The absorption coefficient a(p) [m(-1)] as well as the mass absorption coefficient sigma(p) [m(2)/g] has been estimated for PM10 and PM2.5 in four towns located in southern Poland, based on the assumption that the reflectance of aerosol-laden filters is a good proxy for the absorptivity of aerosols. The optical properties of the airborne particles were also compared with their surface composition obtained by photoelectron spectroscopy (XPS). It was found that coarse particles, which constituted 20-30% of PM10, exhibited insignificant contribution to the absorption. The most absorptive aerosols were found in the towns located in Upper Silesia, a highly industrialized area. This reflects both the relative content of carbon in PM2.5 and the mass concentration of the fine mode. It was found that oxides and sulfates play an important role in promoting the reflectance of light from aerosols in the winter. These results support the suggestion that the revision of existing air quality standards for particulate pollution is needed.