EPA Proposes Keeping Current NAAQS for Nitrogen Dioxide

EPA proposed last month to retain the current National Ambient Air Quality Standards (NAAQS) for nitrogen dioxide (NO₂), without revision. 
 
Under the Clean Air Act, US EPA is required to review its National Ambient Air Quality Standards once every five years to ensure the limits EPA has imposed remain adequate to protect human health. The last review of the NAAQS for nitrogen oxides was completed in 2010. Last year, the Center for Biological Diversity and others filed suit against EPA for failure to review the NAAQS on schedule in 2015. As a result, EPA was ordered to sign off on a final decision within one year.
 
Citing scientific evidence that links even short-term exposure to nitrogen dioxide to effects on the respiratory system, EPA in 2010 promulgated a new short-term exposure limit for NO₂.  At this time, EPA feels the public health implications of further NO₂ reductions are unclear—and given that the current short-term exposure standard is effective at reducing exposure benchmarks above 200 ppb—EPA plans to keep the current standard in place. 
 
Currently, there are two primary NO₂ ambient air quality standards:
 

1. A one-hour, 100 parts per billion standard established in 2010; and
2. A 53 ppb annual average.

 
For more details about EPA’s decision on the NO₂ NAAQS, read the proposal in the Federal Register here.
 

What Are National Ambient Air Quality Standards (NAAQS)?

 
National Ambient Air Quality Standards are protective limits on the volume of six “criteria pollutants” in the air we breathe--nitrogen oxides, sulfur dioxide, carbon monoxide, lead, ozone, and volatile organic compounds (VOCs). 
 
When the volume of a given pollutant exceeds EPA’s limit in a given region (known as “non-attainment”), more restrictive pollution control, reporting, and permitting requirements apply to businesses there. 
 
Read more: Quick Guide: National Air Quality Standards

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Tags: Act, Air, Clean, EPA, NAAQS, nitrogen oxides