Emissions - NOx

What is NOx? 

NOx is the generic term for a group of highly reactive gases, all of which contain nitrogen and oxygen in varying amounts. Many of the nitrogen oxides are colorless and odorless. However, one common pollutant, nitrogen dioxide (NO2) along with particles in the air can often be seen as a reddish-brown layer over many urban areas.Nitrogen oxides form when fuel is burned at high temperatures, as in a combustion process. The primary sources of NOx are motor vehicles, electric utilities, and other industrial, commercial, and residential sources that burn fuels

Where does it come from? 

NOx form when fuel is burned at high temperatures, as in a combustion process. The primary sources of NOx are motor vehicles, electric utilities, and other industrial, commercial, and residential sources that burn fuels. 

• Utilities: 27% 
  
• Motor Vehicle: 49% 
  
• Industrial/Commercial/Residential: 19% 
  
• All Other Sources: 5%
  

NOx is one of the main ingredients involved in the formation of ground-level ozone, which can trigger serious respiratory problems. 

NOx:

• reacts to form nitrate particles, acid aerosols, as well as NO2, which also cause respiratory problems. 
  
• contributes to formation of acid rain. 
  
• contributes to nutrient overload that deteriorates water quality. 
  
• contributes to atmospheric particles, that cause visibility impairment most noticeable in national parks. 
  
• reacts to form toxic chemicals. 
  
• contributes to global warming.
  

NOx and the pollutants formed from NOx can be transported over long distances, 

following the pattern of prevailing winds. This means that problems associated with NOx are not confined to areas where NOx is emitted. Therefore, controlling NOx is often most effective if done from a regional perspective, rather than focusing on sources in one local area.

NOx Emissions Are Increasing. 

Since 1970, EPA has tracked emissions of the six principal air pollutants - carbon monoxide, lead, nitrogen oxides, particulate matter, sulfur dioxide, and volatile organic compounds. Emissions of all of these pollutants have decreased significantly except for NOx, which has increased approximately 10 percent over this period.

Health and Environmental Impacts of NOx 

NOx causes a wide variety of health and environmental impacts because of various compounds and derivatives in the family of nitrogen oxides, including nitrogen dioxide, nitric acid, nitrous oxide, nitrates, and nitric oxide.