The department implements the requirements of the federal Clean Air Act, which sets standards called National Ambient Air Quality Standards to protect public health and welfare. The standards are set for the six criteria pollutants, ozone, sulfur dioxide, nitrogen dioxide, carbon monoxide, lead and particulate matter. Missouri monitors the ambient air for the criteria pollutants and if monitoring data shows that an area does not meet the standard a plan is developed to address emissions that contribute to the problem. Weekly, monthly or quarterly air monitoring data is available within the pollutants web pages below. Learn more about Missouri Air Trends, which includes emissions reported by large point sources.