https://phys.org/news/2018-07-chemists-air-pollution.html

The little guys are actually freshly minted versions of highly prevalent components of Earth's atmosphere. Aerosols are created when fine solid particles or liquid droplets are suspended in air or another gas. Dust, haze and smoke are all examples of aerosols. They play a vital role in influencing air quality and the Earth's climate.

This summer, O'Brien, assistant professor of chemistry at William & Mary, is teaming up with Nathan Kidwell, also an assistant professor of chemistry. The two chemists have set their sights on brown carbon, a class of organic molecules that primarily result from fossil fuel emissions and biomass burning.