Particulate matter (PM), is a complex mixture of extremely small particles and liquid droplets. PM2.5, or fine particulate matter, is defined as particles 2.5 micrometers in diameter or smaller. Fine particles are constituents in smoke and haze. They can be directly emitted from sources like fires, or they can form when gases emitted from power plants, industries and automobiles react in the air.
Small particles less than 2.5 micrometers in diameter pose the greatest health risks because they travel far and embed deeper into the lungs than large particles. Some fine particles even enter the bloodstream. PM2.5 exposure can affect both the lungs and heart. Numerous scientific studies have linked particle pollution to a variety of health problems, including:
Though the purpose of the primary air quality standards is to protect public health, particulate matter, especially PM2.5, is believed to play a role in visibility. The emission and transport of particulate matter as it relates to visibility remain on the state and national agenda. There are four federal standards for PM2.5: identical primary and secondary standards for short term (24-hr) values, and separate annual primary and secondary standards. Oklahoma is in attainment with all PM2.5 standards.
The division monitored PM2.5 at eleven locations in both highly populated areas and areas of specific concern. PM2.5 is monitored with two methods: a filter-based method (24-hr sampling on a Teflon filter taken on a daily, 3-day, or 6-day schedule) and a continuous sampling method (hourly reports). Current data may be accessed here.
Primary and Secondary PM2.5 24-hour standards: 35 μg/m3 (3 yr avg)
Primary Annual Arithmetic Mean PM2.5 standard: 12 μg/m3 (3 yr avg)
Secondary Annual Arithmetic Average PM2.5 standard: 15 μg/m3 (3 yr avg)
2016 PM2.5 Values vs 24 Hour NAAQS
3 yr avg ('14-'16) of 98th percentile
24 hr avg PM2.5 concentration (μg/m³)
*Incomplete Data Set (site closed in 2016)
2016 PM2.5 Values vs Annual Mean NAAQS
3 yr avg ('14-'16) of Annual Weighted Mean
PM2.5 concentration (μg/m³)
*Incomplete Data Set (site started August 2014)