What is Particulate Matter?

Airborne particulate matter (PM) is not a single pollutant, but rather is a mixture of many chemical species. It is a complex mixture of solids and aerosols composed of small droplets of liquid, dry solid fragments, and solid cores with liquid coatings. Particles vary widely in size, shape and chemical composition, and may contain inorganic ions, metallic compounds, elemental carbon, organic compounds, and compounds from the earth’s crust. Particles are defined by their diameter for air quality regulatory purposes. Those with a diameter of 10 microns or less (PM10) are inhalable into the lungs and can induce adverse health effects. Fine particulate matter is defined as particles that are 2.5 microns or less in diameter (PM2.5). Therefore, PM2.5 comprises a portion of PM10.

What is the Difference Between PM10 and PM2.5?

PM10 and PM2.5 often derive from different emissions sources, and also have different chemical compositions. Emissions from combustion of gasoline, oil, diesel fuel or wood produce much of the PM2.5 pollution found in outdoor air, as well as a significant proportion of PM10. PM10 also includes dust from construction sites, landfills and agriculture, wildfires and brush/waste burning, industrial sources, wind-blown dust from open lands, pollen and fragments of bacteria.

PM may be either directly emitted from sources (primary particles) or formed in the atmosphere through chemical reactions of gases (secondary particles) such as sulfur dioxide (SO2), nitrogen oxides (NOX), and certain organic compounds. These organic compounds can be emitted by both natural sources, such as trees and vegetation, as well as from man-made (anthropogenic) sources, such as industrial processes and motor vehicle exhaust.

Please find more PM information on the Air Resources Board website HERE.

Particulate Matter Attainment Plan

The Mendocino County Air Quality Management District has adopted a PM Attainment Plan. The plan includes a description of local air quality, the sources of local PM emissions, and recommended control measures to reduce future PM levels.

PM Attainment Plan

PDF Presentations

Board Presentation
Workshop Presentation
Sonoma Technologies Report (Executive Summary)
Sonoma Technologies Report (Full)

PDF Health Effects

PM10 and Infant Mortality (ARB)
Recent wood smoke research(from State of Washington)
Mechanisms of PM Toxicity (ARB)
Air Resources Board Press Release on 10-year Children's Health Study

PDF Statewide Information

Economic Impacts of PM pollution (Air Resources Board - ARB)
PM exposure assessment in vehicles (ARB)

 

 

Please see below table for more information on PM and Ozone pollutants.

   Particulate Matter (PM)  Ozone (smog)
 Type of Pollutant  Small Particles  Gas
 Where does it come from?
  •  Combustion sources: cars, trucks, trains, ships, aircraft, certain facilities, meat cooking, residential wood burning, wildfires. These sources emit fine particle pollution with diameters generally 2.5 micrometers and smaller (PM2.5)
  • Natural sources: dust storms contain inhalable particles with diameters that are 10 micrometers and smaller (PM10), and particles larger than 10 micrometers.
  • Much of the PM2.5 in the inland regions is formed from several pollutants mixing or reacting in the air.
  •  Ozone is formed when several gaseous pollutants react in the presence of sunlight.
  • Most of these gases are emitted from mobile sources.
 Is it visible? Yes, but only at very high levels. No 
 What are the main health effects? Cardiovascular and respiratory  Respiratory 
 What are the most affected areas?
  •  Areas near major roadways, ports, railyards, and other combustion sources
  • Inland areas and valleys
 Inland areas and valleys 

Contact Us

Phone:
707-234-6360

E-Mail

Mendocino County Air Quality Management District
1100A Hastings Road
Ukiah, California 95482
Mail: P.O. Box 247
Ukiah, California 95482
Office Hours
The District's office is open:
8:00 a.m. to 5:00 p.m. Monday though Friday
(closed from Noon to 1:00 p.m. for lunch)