The Environmental Protection Agency plans to enforce stricter guidelines to reduce ozone in several U.S. counties. The EPA says 345 out of 700 monitored counties will have to improve their air quality because it is currently far too dirty to be inhaled and could result in heart and asthma attacks. The areas with the most dangerous levels of pollution will have up to 20 years to make changes that will allow the air to meet requirements and the EPA is optimistic that the number of counties in violation of standsards will drop to 28 by 2020.

Despite the new standards, health professionals and some members of Congress claim the efforts aren't enough and need to be even more stringent. The new standards will reduce the amount of ozone in the air from the former 80 parts per billtion to a maximum of 75 parts per billion, however two advisory boards had previously recommended the number be reduced to the range of 60 to 70 parts per billion. The panels claim numbers any higher could result in health risks amongst children and senior citizens.

"Today's decision means millions of Americans will not get the protection that the law requires," said Bernadette Toomey, president of the American Lung Association, which had strongly urged the EPA to follow the advice of the science boards.

Stephen Johnson, EPA administrator, has responded to criticism, saying "In the end it is a judgment. I followed my obligation. I followed the law. I adhered to the science."

» MSNBC Environment