What is Particulate Matter?
A. Particulate matter pollution consists of very small liquid and solid particles floating in the air. Of greatest concern to the public health are the particles small enough to be inhaled into the deepest parts of the lung. These particles are less than 10 microns in diameter–about 1/7th the thickness of a human hair–and are known as PM10. This includes fine particulate matter known as PM2.5. PM10 is a major component of air pollution that threatens both our health and our environment. Construction activities disturbing the soil within Maricopa County are regulated by the Maricopa County Air Quality Department. Although regulations require everyone to minimize emissions from dust generating operations, projects that have a total disturbed surface area of 1/10 acre (4,356 sq ft) or more are required to obtain a valid Dust Control Permit. The project is required to have a valid permit before the soil is disturbed.
Particulate matter, or PM, is the term for particles found in the air, including dust, dirt, soot, smoke, and liquid droplets. Particles can be suspended in the air for long periods of time. Some particles are large or dark enough to be seen as soot or smoke. Others are so small that individually they can only be detected with an electron microscope. Some particles are directly emitted into the air. They come from a variety of sources such as cars, trucks, buses, factories, construction sites, tilled fields, unpaved roads, stone crushing, and burning of wood. Other particles may be formed in the air from the chemical change of gases. They are indirectly formed when gases from burning fuels react with sunlight and water vapor. These can result from fuel combustion in motor vehicles, at power plants, and in other industrial processes.
Particles found in the air we breathe, or “particulate matter” are a health concern in many areas. EPA has identified particles that are smaller than 10 microns (or 1/100 of a millimeter) as impacting human health. These particles, referred to as “PM10” become trapped in the lungs and cause irritation and injury to the lungs, worsen existing ailments, and can even cause death. There are many sources of particulate matter – fuel combustion, industrial practices and manufacturing, electric generation, waste disposal, wildfires, managed burning, fugitive dust, and crustal materials. Sources, particle size, and particle compositions vary extensively within a single area and between different areas. In July 1997, EPA promulgated revised standards for particulate matter. Under these rules, EPA established a new particulate matter standard that specifically addresses particles smaller than 2.5 microns, or “PM2.5.” The PM10 standard was retained. Both standards will provide continued reduction
Particulate matter (PM10 and PM2.5) is comprised of solid particles or liquid droplets tiny enough to remain suspended or floating in the air for up to weeks at a time. Of greatest concern to the public health are the particles small enough to be inhaled into the deepest parts of the lung. These particles are less than 10 microns in diameter–about 1/7th the thickness of a human hair–and are known as PM10. This includes fine particulate matter known as PM2.5. PM2.5 has a specific range of particles 2.5 micrometers or less. PM10 is a major component of air pollution that threatens both our health and our environment. General PM composition can include everything from fine dust to carbon (soot), and can be microscopic or visible to the naked eye. Particulate matter is generated from a variety of sources including traffic on paved and unpaved roads, combustion, and earth-moving activity such as mining, farming and construction.
