Handbook of Environmental Engineering

16Atmospheric Aerosols and Their Measurement

Christian M. Carrico

Department of Civil and Environmental Engineering, New Mexico Institute of Mining and Technology, Socorro, NM, USA

16.1 Overview of Particulate Matter in the Atmosphere

An aerosol is a colloidal suspension of particulate matter (PM) – solid and/or liquid – that is suspended in a gaseous carrier, most typically air. A cubic meter of air with a mass of approximately 1.2 kg or 1.2E9 μg at sea level may contain only a few μg of PM mass in a pristine environment and 100 μg or higher in a highly polluted urban area. Despite their small mass fraction in the air, the atmospheric impacts of aerosols upon air quality are profound and include cloud formation, meteorological interactions, visibility impairment, atmospheric chemistry effects, and human health impacts (Seinfeld and Pandis, 2016). Not all aerosol effects are necessarily detrimental. For example, transport of aeolian dust is a major pathway for delivery of mineral species and nutrients to oceans and other continents. Aerosols due to volcanic eruptions, another natural source, have long been recognized as having a climate influence. Following the eruption of Mt. Pinatubo in 1992, the Earth cooled for a couple years by about 0.5 °C due to the stratospheric injection of the precursor SO₂ and dust. Aerosols from human sources have recently been identified as an important component of the climate system (IPCC, 2013).

Aerosols have numerous and diverse anthropogenic ...