| New Air Quality Standards |
 |
| Mississippi has always been designated as attaining all U.S. Environmental Protection Agency (EPA) ambient air quality standards. However, EPA has recently revised standards for ground-level ozone and fine particulate matter (PM2.5) that are designed to be more protective of human health and welfare. These standards present new challenges for the state to continue to be designated as attainment. |
| |
| Ozone |
In 1997, new primary and secondary ambient air quality standards for ground-level ozone were issued. The standards were changed from 0.12 parts per million (ppm) based on a one-hour averaging period to 0.08 ppm based on an eight-hour averaging period. However, the standards were not implemented until 2004 because of lawsuits and court rulings.
In 2004, all counties in Mississippi where ozone ambient air monitoring occurred were designated by EPA as attaining these standards based on 2001 – 2003 air monitoring data.
In 2008, EPA again lowered the ozone standards. The primary and secondary standards were changed from 0.08 ppm to 0.075 ppm. Attainment/nonattainment designations are proposed to be made in March 2010 based on 2007 – 2009 air monitoring data. It is not known at this time what effect this lower standard will have on Mississippi. |
|
For more information about Ozone, voluntary reduction programs and a daily ozone air quality forecast, click here.
|
| |
| PM2.5 |
In 1997, EPA set primary and secondary ambient air quality standards for fine particulate matter (PM2.5). Previously, there were no standards for this pollutant and it was not monitored. The primary and secondary PM2.5 standards were set at an annual average of 15 µg/m3 and a 24-hour average of 65 µg/m3. However, the standards were not implemented until 2004 because of lawsuits and court rulings.
In 2005, all counties in Mississippi where PM2.5 ambient air monitoring occurred were designated by EPA as attaining these standards based on 2001 – 2003 air monitoring data.
In 2006, EPA lowered the 24-hour average primary and secondary standards from 65 µg/m3 to 35 µg/m3. The annual average standard remained at 15 µg/m3. Attainment/nonattainment designations are proposed to be made in 2009 based on 2005 – 2007 air monitoring data. All counties in Mississippi where PM2.5 ambient air monitoring occurred will be designated as attaining these standards. |
| |
| Contact |
| For more information on current New Air Quality Standards and Attainment click here. |