Atmospheric aerosol particles, also known as atmospheric particulate matter, particulate matter (PM), particulates, or suspended particulate matter (SPM) are microscopic solid or liquid matter suspended in Earth's atmosphere.

The term aerosol commonly refer to the particulate/air mixture, as opposed to the particulate matter alone. Sources of particulate matter can be natural or anthropogenic. They have impacts on climate and precipitation that adversely affect human health .

Long–range transport of polluted air masses can significantly affect surface particulate matter levels. PM10 and PM2.5 daily-average ponderal values alone are not sufficient to investigate the occurrence of such phenomena and consequently do not give significant information for source apportionment.. Atmospheric ammonia (NH3) has great environmental implications due to its important role in ecosystem and global nitrogen cycle, as well as contribution to secondary particle formation. emission sources, air masses originated from or that have passed over ammonia rich areas, e.g. rural and industrial sites, increase the observed NH3 concentrations inside the urban area. Remarkable high-frequency NH3 variations measure at the industrial site, indicating instantaneous nearby industrial emission peaks. strong positive exponential correlations between NH4+/(NH4++NH3) and sulfate-nitrate-ammonium (SNA) aerosols, PM2.5 mass concentrations, implying a considerable contribution of gas-to-particle conversion of ammonia to SNA aerosol formation. Lower temperature and higher humidity conditions were found to favor the conversion of gaseous ammonia to particle ammonium, particularly in autumn.

Long–range transport of anthropogenic pollution is contrasted with that of pollution produced by natural processes such as dust storms or natural forest fires. Haze is an atmospheric phenomenon where dust, smoke and other dry particles affect visibility and obscure the clarity of the sky. Sources for haze particles include farming, traffic, industry, and wildfires. Haze often occurs when dust and smoke particles accumulate in relatively dry air. Subsequent increases in humidity can result in hygroscopic growth and decreased visibility. When weather conditions block the dispersal of smoke and other pollutants they concentrate and form a usually low–hanging shroud that impairs visibility and may become a respiratory health threat. Industrial pollution can also result in dense haze.