The SacMetro AQMD is responsible for cleaning the air to meet state and federal health standards so we all breathe easier. The area's two biggest air pollutants are ground-level ozone and particulate matter 2.5. In Sacramento County, the majority of air pollution during the summer comes from mobile sources, which are the cars, trucks, buses, agriculture and construction equipment that are used every day. In the wintertime, the majority of air pollution comes from wood burning in residential fireplaces and wood stoves. Together we work to improve the health and quality of life for residents.