Why Control SO2 and NOx?
Why EPA is Addressing Emissions of SO2 and NOx • EPA established more protective fine particle and 8-hour ozone national air quality standards in 1997. Litigation and the need to establish a nationwide air monitoring system for fine particles delayed the implementation of these standards, but implementation is now moving forward. Areas not meeting these standards, known as “nonattainment” areas, were designated in 2004. These state and local governments are moving forward with plans to protect public health by attaining the standards as quickly as possible. • Sulfur dioxide (SO2) and nitrogen oxides (NOx) contribute to the formation of fine particles (PM) and NOx contributes to the formation of ground-level ozone. • Many sources contribute to levels of fine particle pollution and ozone that exceed national air quality standards. Some of these pollutants may originate hundreds or thousands of miles from the areas where violations are detected. The Clean Air Act’s “good neighbor provisio
