The US Environment Protection Agency (EPA) said that the pollution standards adopted back in 1997 are too weak and the agency has proposed tighter new rules for ground-level ozone.

Breathing air containing ozone can reduce lung function, thereby aggravating asthma or other respiratory conditions.  Ozone exposure has also been associated with increases in respiratory infection susceptibility, medicine use by asthmatics, doctors’ visits, emergency department visits and hospital admissions.  Ozone exposure also may contribute to premature death in people with heart and lung disease.

"Ozone's impacts are more significant than we previously thought," EPA administrator Stephen Johnson said.

EPA’s proposal would revise both ozone standards: the primary standard, designed to protect human health; and the secondary standard, designed to protect welfare (such as vegetation and crops).Currently both standards are identical an 8-hour standard of 0.08 parts per million (ppm).

“Let me make it very clear that based upon the science that’s before me today, the current standard is insufficient to protect public health, and I’m proposing to tighten it,”, Johnson added.

For the primary standard EPA proposes a level within the range of 0.070-0.075 ppm (70 -75 ppb) and for the second standard the agency has two options: cumulative standard within the range of 7 to 21 ppm-hours or identical to the proposed primary 8-hour standard.

The proposed EPA’s standards will make the object of 90-day public debate and the agency will issue the final numbers by March 12, 2008.

The EPA, which monitors 639 counties nationwide, says 104 of them are out of compliance with the current standard. If the standard went to 75 parts per billion, 398 counties would be out of compliance; if it went to 70 parts per billion, 533 counties would be out of compliance.

A panel of experts, called the Clean Air Scientific Advisory Committee, which includes members with academic and industry backgrounds, analyzed the available data. They unanimously concluded the current standard does not protect public health and recommended a standard between 0.060 and 0.070 ppm/-8-hours.

The National Association of Manufacturers and other industry groups called for maintaining the current rules, arguing that lowering it would be costly and unnecessary.