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Particulate Matter

What is it?
Particulate matter is a complex mixture of extremely small particles and liquid droplets. These airborne particles can include acids, organic chemicals, metals, dust, dirt, soot, and smoke.  These particles can vary in size and; therefore, also vary in intensity of health effects. The Environmental Protection Agency (EPA) groups particle pollution into two categories:

  • Inhalable Coarse Particles, or PM10  - found near roadways and dusty industries, are larger than 2.5 micrometers and smaller than 10 micrometers in diameter.

  • Fine Particles, or PM2.5 - found in smoke and haze, are 2.5 micrometers in diameter and smaller. These particles can be directly emitted from sources such as forest fires, or they can form when gases emitted from power plants, industries and automobiles react in the air.

Where does it come from?
These small particles come from a variety of places including dust from paved or unpaved roads and crushing or grinding operations.  They can also be formed when gases from burning fuels, which are released from motor vehicles and industries, react with sunlight and water vapor.

How is it harmful?
Fine particles are believed to pose the greatest health threat.  Their small size gives them the ability to travel into and become lodged deep within the lungs.  Some of the effects can be:

  • Premature death
  • Non-fatal heart attacks
  • Respiratory disease
  • Reduced lung function
  • Changes in heart rate
  • Irregular heartbeat

What’s being done to help?
EPA currently has two primary standards for fine particles: an annual standard set at 12 micrograms per cubic meter (µg/m3) over a three-year average of the annual mean, designed to protect against effects caused by short-term exposure (days to weeks) and longer-term exposure (seasons to years); and a 24-hour standard set at 35 µg/m3 for a three-year average of the annual 98th percentile of values, which is designed to provide additional protection on days with high peak PM2.5 concentrations.  These standards are subject to change as updated scientific information is obtained on the effects of this pollutant on human health.

Regional Matters:
There are various programs in place to help reduce the PM levels from mobile sources throughout the North Central Texas region. 

The ten-county region of North Central Texas currently falls within both the 24-hour and annual concentration limits set by the EPA.  There are currently four monitors that measure PM10 and 14 monitors that measure PM2.5.

4/27/2018  JPL/MG %Trans

 North Central Texas Council of Governments | 616 Six Flags Drive P.O. Box 5888 Arlington, TX 76005-5888
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