Learn About Particle Pollution Designations
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Particle pollution, also known as particulate matter (PM), contains microscopic solids or liquid droplets that are so small that they can be inhaled and cause serious health problems. The size of particles is directly linked to their potential for causing health problems. Small particles less than 10 micrometers (PM10) in diameter pose the greatest problems, because they can get deep into your lungs, and some may even get into your bloodstream. Fine particles less than 2.5 micrometers (PM2.5) also affect the environment. In fact they are the main cause of reduced visibility (haze) in parts of the United States, including many of our treasured national parks and wilderness areas.
Within 2 years of setting a new or revised National Ambient Air Quality Standard (NAAQS), the Clean Air Act requires EPA to designate areas as meeting (attainment) or not meeting (nonattainment) the standard.
After we have issued a new or revised NAAQS, the Clean Air requires states to submit, and gives tribes the opportunity to submit, initial area designation recommendations within 12 months. EPA completed the designations for the 2012 fine particle pollution standards (PM2.5) in multiple rounds. EPA finalized initial designations for most of the country on December 8, 2014. However, because of quality assurance/quality control issues, EPA invalidated data from a number of monitoring sites that would have been used to assess compliance with the 2012 PM2.5NAAQS. As a result, these areas were designated “unclassifiable.” Because of data validity issues, EPA deferred designations for 10 areas until additional monitoring data were collected. On March, 31, 2015, EPA established or revised initial area designations and corrected an inadvertent error for one area in the initial area designations. On August 30, 2016, EPA issued designations on certain areas in Georgia and Florida.
EPA’s final designations are based on:
- The most recent 3-years of air quality monitoring data,
- Recommendations submitted by the states and tribes, and
- Other technical information.
EPA provided guidance for the particle pollution designations process in the preamble to the PM NAAQS rule. As in recent designations, when making boundary recommendations, EPA encouraged air agencies to evaluate five factors:
- air quality data,
- emissions and emissions-related data,
- geography/topography, and
- jurisdictional boundaries.