EPA Strengthens Air Quality Standard for NO2

The USA Environmental Protection Agency has announced a new national air quality standard for nitrogen dioxide (NO2) to "protect millions of Americans from peak short-term exposures, which primarily occur near major roads." Short-term exposures to NO2 have been linked to impaired lung function and increased respiratory infections, especially in people with asthma.

The agency set the new one-hour standard for NO2 at a level of 100 parts per billion (ppb). The EPA also is retaining the existing annual average standard of 53 ppb. NO2 is formed from vehicle, power plant and other industrial emissions, and contributes to the formation of fine particle pollution and smog. Earlier this month, the EPA proposed to tighten the nation’s smog standards to protect the health of all Americans, especially children.

The EPA is establishing new monitoring requirements in urban areas that will measure NO2 levels around major roads and across the community. Monitors must be located near roadways in cities with at least 500,000 residents. Larger cities and areas with major roadways will have additional monitors. Community-wide monitoring will continue in cities with at least 1 million residents.

Update (27 Jan)

CAI-Asia recently conducted a survey on the status of NAAQS (including any plans for revisions of their NAAQS) in selected Asian countries. Comparing the one-hour average NO2 standards in 14 Asian countries with the new one-hour average NO2 standard set by USA EPA, only Japan and South Korea have one-hour average NO2 standards equal or stricter than the USA EPA standard (Table 1). Vietnam had one-hour average NO2 standard equivalent to WHO AQG, as with the proposed air quality objectives (AQO) of Hong Kong.

The remaining Asian countries had more lenient one-hour average NO2 standards relative to the USA EPA and WHO AQG. Based on the results of the survey, aside from Hong Kong, none of the Asian countries have any plans of revising their one-hour average NO2 standards.