The US Environmental Protection Agency (EPA) revealed yesterday (29th June) that it is set to crack down on the amount of nitrogen dioxide emitted in the country.

Under the terms of the new proposals, states would be required to limit the concentration of the gas to a maximum of 80 to 100 parts per billion over any one-hour period.

The move is designed to cut out the localised spikes in pollution that ensue from the current year-long regulations, which restrict the concentration to 53 parts per billion annually.

Discussing the decision, EPA Administrator Lisa Jackson said: "We're updating these standards to build on the latest scientific data and meet changing health protection needs.

"In addition to limiting annual average concentrations, we're preventing high NO2 levels for shorter periods of time and adding stronger monitoring in areas near roadways, where the highest levels of NO2 are often found."

Ms Jackson added that the new legislation would help to make the current standard more watertight and "provide important additional protections where they are needed most".

The new monitoring standards will see NO2 levels checked within 50 metres of major roads in cities with at least 350,000 residents, while 'area-wide' assessments will occur in cities with over one million people.

Nitrogen dioxide is known to cause respiratory problems - particularly in those with asthma - but pgm-based particulate filters are increasingly playing a role in reducing such emissions from diesel vehicles.

Sources:

EPA Proposes New Nitrogen-Dioxide Air Standard (29/06/09)

EPA Proposes Stronger Air Quality Standards for Nitrogen Dioxide (29/06/09)

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