Sulfur Dioxide Trends
Air quality monitors measure concentrations of SO2 throughout the country. EPA, state, tribal and local agencies use that data to ensure that SO2 in the air is at levels that protect public health and the environment. Nationally, average SO2 concentrations have decreased substantially over the years. The charts below show national and regional trends in SO2 concentrations. For information on SO2 standards, sources, health effects, and programs to reduce SO2, please see our Sulfur Dioxide Pollution page.