A new national air quality standard for nitrogen dioxide (NO2) has been set up in the US aimed at reducing short-term exposures that occur near major roads.

The US Environmental Protection Agency (EPA) will set up new air pollution monitors near heavily polluted roadways in urban areas to enforce the new one-hour standard for NO2 level – 100 Parts Per Billion – which the EPA has revised for the first time in 35 years.

Monitors will be located near roadways in cities with at least 500,000 residents and larger cities and areas with major roadways will have additional monitors.

The locations not meeting the standard using existing monitors are expected to be identified by January 2012, with the new monitors scheduled to enter operation in January 2013.

NO2, which is formed from vehicle and industrial emissions, contributes to the formation of fine particle pollution as well as smog and can trigger lung problems and respiratory infections.