|Map of final PM2.5 non-attainment areas. Click to enlarge.|
The US Environmental Protection Agency (EPA) has notified 25 governors and 23 tribal leaders that certain areas in their states and tribal lands do not meet the agency’s 24-hour national ambient air quality standards (NAAQS) for fine particulate matter (PM2.5). (Earlier post.)
After issuing its intended designations (e.g., attainment, nonattainment) for the 24 hour PM2.5 standard, revised in 2006 (earlier post) earlier this year, EPA reviewed recommendations from states and tribes along with public comments before making its decision to designate 211 counties and parts of counties as not meeting EPA’s PM 2.5 standards. These nonattainment areas include counties with monitors violating the standards and nearby areas that contribute to that violation.
Affected states and tribes will be required to take steps to reduce the pollution that forms these particles. The majority of US counties—more than 3,000—including tribal lands will not have to take additional steps to meet these standards, but will need to continue working to maintain clean air.
State, local and tribal governments must detail control requirements in plans demonstrating how they will meet the 2006 24-hour PM2.5 NAAQS. Those plans are known as state or tribal implementation plans, or SIPs/TIPs. States must submit their plans to EPA within three years after the Agency makes final designations - by April 2012. Tribes also may submit plans, but are not required to do so. Areas are required to attain clean air by 2014. EPA may grant attainment date extensions for up to five additional years in areas with more severe PM2.5 problems and where emission control measures are not available or feasible.
In 2006, EPA increased the 24-hour fine particle standards from 65 micrograms per cubic meter (µg/m3) to 35 µg/m3 of air. Nationwide, monitored levels of fine particle pollution fell 11% from 2000 to 2007.
Fine particles can either be emitted directly, or they can form in the atmosphere from reactions of sulfur dioxide and nitrogen oxides. Exposure to fine particle pollution can cause a number of serious health problems including aggravated asthma, increased hospital admissions and emergency room visits for respiratory and cardiovascular disease, heart attacks and premature death.