Air pollution impacts the water quality of the Chesapeake Bay as well as public health. The Chesapeake Bay airshed is nine times the size of the Bay watershed. Stationary sources (for example, powerplants, and factories), mobile sources (for example, cars) and agriculture within the airshed contribute to air pollution in the Bay watershed. Pollutants wash out of the air when it rains or fall to land or water as dry particles, known as atmospheric deposition, causing water quality problems for the Bay. According to scientists, approximately one-third of the total nitrogen pollution in the Chesapeake Bay is from air sources in the form of nitrogen oxides or ammonia emissions. Too much nitrogen in the water causes algae blooms, which restrict oxygen levels in the water leading to dead zones that suffocate marine life.