The Clean Air Act requires the US EPA to set national standards for six common air pollutants, called “criteria pollutants.” The national standards, called National Ambient Air Quality Standards (NAAQS), are set to protect health, the environment, and property. The criteria pollutants are ground-level ozone, fine particles, lead, nitrogen dioxide, carbon monoxide, and sulfur dioxide. Each state must demonstrate it is complying with these standards by monitoring its air quality. If a state fails to comply with one of the standards, it must develop a plan to come into compliance.
The EPA is also required to review the science related to the environmental and health effects associated with the criteria pollutants every five years. If new research indicates an existing standard is not protective, the EPA must strengthen the standard. Over the years, as scientists have found health effects at lower and lower levels of air pollution, EPA has regularly tightened the national standards.
To protect human health and continue to comply with national standards that get ever more stringent, Minnesota must stay proactive in reducing emissions and air pollution levels in the state.
The MPCA monitors for these pollutants across the state to ensure we continue to comply with the national standards. Currently, Minnesota is complying with all of the NAAQS. To see our monitoring data for all of the criteria pollutants, visit our criteria pollutant data explorer.