Nitrogen dioxide is a foul-smelling gas. It comes primarily from the burning of fossil fuels — coal, oil and gas. NO2combines with volatile organic compounds (VOCs) in the presence of sunlight and heat to create ozone. (VOCs are compounds with carbon that easily become vapors or gases.)
In 2010, EPA revised the one-hour NO2 standard to 100 parts per billion. An area is in compliance if the design value is at or below the standard. The one-hour standard is based on a three-year design value, which is calculated by taking the 98th percentile of the daily high one-hour average concentrations recorded each year, for three years, and averaging the three years together. The annual standard of 0.053 parts per million is based on the annual arithmetic mean and is not to be exceeded.
Departmental information about nitrogen dioxide (NO2)
- 2010 standard and related documents