Spatial characteristics of the PM/PM ratio and its indicative significance regarding air pollution in Hebei Province, China.

Particulate matter (PM) is the primary air pollutant in northern China. The PM/PM ratio has been used increasingly as an indicator to reflect anthropogenic PM pollution, but its advantages compared with individual PM or PM concentrations have not been proven sufficiently by experimental data. By dividing Hebei Province (China) into seven natural ecological regions, this study investigated the spatial characteristics of the PM/PM ratio and its relationships with PM, PM, economic density, and wind speed.