"The Obama administration on Monday proposed to strengthen a key air pollution health standard to better protect children and people with respiratory illnesses.

The Environmental Protection Agency said it wants to tighten the air quality requirement for nitrogen dioxide that is released from motor vehicles, coal burning power plants and factories.

The pollutant is among those the EPA is required to examine periodically to determine that concentrations are at a level to ensure healthy air. Nitrogen dioxide can cause respiratory problems and is of special danger to children and people suffering from asthma and other respiratory illnesses.

The federal air quality standard for nitrogen dioxide, as it applies to health, has not been changed in 35 years."

H. Josef Hebert reports for the Associated Press June 29, 2009. [2]