Air quality has steadily improved in the St. Louis region due in large part to improvements in motor vehicle technology and gasoline formulation, regulations on industry and power plants, vehicle inspection and maintenance programs, and efforts to reduce congestion and improve traffic flow (St. Louis Air Quality Timeline).
Since the 1977 amendments to the Clean Air Act, East-West Gateway Council of Governments (EWG) has been the lead air quality and transportation planning agency for the St. Louis region. EWG activities include: working with Missouri and Illinois on strategies to reduce emissions from motor vehicles through increasing the use of mass transit and ridesharing and improving traffic flow; performing conformity determination to ensure that transportation programs and projects do not have a negative impact on air quality; serving as a regional clearinghouse of data collected during the ozone season; and facilitating the Air Quality Advisory Committee (AQAC).
