EJScreen Indicators Overview – Nitrogen Dioxide (NO2)
What is the NO2 indicator?
The “NO2 indicator” measures how much surface level Nitrogen Dioxide (NO2) people might be exposed to. EJScreen presents surface level NO2 concentrations using percentile rank, ranging from 0 (lowest) to 100 (highest) with higher scores representing higher concentrations. This indicator does not designate compliance with the national ambient air quality standard for NO2.
Why is NO2 important?
- Nitrogen Dioxide (NO2) is part of a class of highly reactive gases known as oxides of nitrogen or nitrogen oxides (NOx). NO2 primarily gets in the air from fuel burning, usually from emissions from cars, trucks and buses, power plants, and off-road equipment. NO2 reacts with other chemicals in the air to form both particulate matter and ozone.
- Breathing air with a high concentration of NO2 can irritate airways in the respiratory system. Exposures over short periods of time can aggravate respiratory diseases, particularly asthma, leading to respiratory symptoms (such as coughing, wheezing, or difficulty breathing), hospital admissions, and visits to emergency rooms. Longer exposures may contribute to the development of asthma and potentially increase susceptibility to respiratory infections. People with asthma, children, and older adults are generally at greater risk of health effects from exposure to NO2.
- NO2 and other NOx interact with water, oxygen, and other chemicals in the atmosphere to form acid rain. Acid rain harms sensitive ecosystems such as lakes and forests.
- The nitrate particles that result from NOx can also make the air hazy and difficult to see through.
How does EJScreen create the NO2 indicator?
- EJScreen uses NASA Goddard Space Flight Center, Goddard Earth Sciences Data and Information Services Center (GES DISC) satellite imagery of average annual NO2 concentrations for its NO2 This product is part of an effort by NASA's Health and Air Quality Applied Sciences Team (HAQAST).
- This NASA product provides NO2 values at an approximately 1 km resolution. These values are then aggregated and averaged to census block values and expressed in parts per billion (by volume).
- For technical details on the calculations and source data, visit the EJScreen Technical Documentation.
Moving forward – What you can do
- Stay informed on the latest relevant information and resources on the EPA NO2 Pollution site.
- Learn about the health effects of NO2.
- See what the EPA and others are doing to reduce NO2 pollution. The EPA has national and regional rules that reduce NO2 and help state and local governments meet national air quality standards. Learn about how NO2 is controlled and how air quality standards help reduce pollution.