Atmospheric scientists study the chemical composition of the atmosphere. More specifically, they look at how atmospheric gases, liquids, and solids interact both with each other and with the earth's surface. This helps people understand such phenomena as air pollution, ozone depletion, and climate change. Shawn Urbanski is a research physical scientist at the U.S. Forest Service’s Rocky Mountain Research Station in Missoula, Montana. He studies wildfire smoke chemistry and the impact of wildfire smoke on air quality.