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Particulate matter, called PM, are very small dust and soot particles. When we talk about PM, we talk about “PM10” and “PM2.5”. PM10 is matter that is 10 micrometers in diameter. That would be about one-seventh the width of a strand of human hair. PM2.5 is even smaller - measuring 2.5 micrometers or less.
PM is made up of a number of components. Soil and dust particles and certain metals are emitted directly into the air as PM. The primary human-caused sources of PM include blowing dust from construction sites and agricultural activities, as well as combustion products from solid fuels such as fly ash (from power plants), carbon black (from automobiles and diesel engines) and soot (from fireplaces and wood stoves). Along the Wasatch Front, the effects of PM can be seen as the thick brownish haze that gets trapped in the valleys in winter months when the air is very still.
During the winter months, the Utah Department of Environmental Quality issues advisories through the news media. An “Air Action” advisory warns that pollution levels are beginning to build up and residents are asked to reduce driving by combining trips, carpooling, or using mass transit; residents are also encouraged to not use wood burning devices. An “Air Alert” advisory indicates that pollution levels are high and residents should limit driving by combining trips, carpooling, or using mass transit; in addition, wood burning is prohibited. The Department also asks industry to take proper steps during an “Air Action” and “Air Alert” periods.
For more information on what you can do to help air quality, click here.
What the Numbers Mean
Particulate Matter (PM) is reported in micrograms per cubic meter or µg/m3. The particulate is collected on a filter and weighed. This weight is combined with the known amount of air that passed through the filter to determine the concentration in the air.
EPA revised the National Ambient Air Quality Standards for PM pollution on September 21, 2006. EPA lowered the 24-hour PM2.5 threshold from 65 μg/m3 to 35 μg/m3. The standard is based on the 98th percentile of 24-hour PM2.5 concentrations averaged over three years. The PM10 24-hour standard is set at 150 μg/m3 and is calculated as the three year average of the highest monitored concentrations.
Both fine and coarse particles can accumulate in the respiratory system and are associated with numerous health effects. Coarse particles can aggravate respiratory conditions such as asthma. Exposure to fine particles is associated with several serious health effects, including premature death. Adverse health effects have been associated with exposures to PM over both short periods (such as a day) and longer periods (a year or more).
When exposed to PM, people with existing heart or lung diseases—such as asthma, chronic obstructive pulmonary disease, congestive heart disease, or ischemic heart disease—are at increased risk of premature death or admission to hospitals or emergency rooms.
The elderly also are sensitive to PM exposure. They are at increased risk of admission to hospitals or emergency rooms and premature death from heart or lung diseases. When exposed to PM, children and people with existing lung disease may not be able to breathe as deeply or vigorously as they normally would, and they may experience symptoms such as coughing and shortness of breath. PM can increase susceptibility to respiratory infections and can aggravate existing respiratory diseases, such as asthma and chronic bronchitis, causing more use of medication and more doctor visits.
If you have any questions please contact your health care provider.
Sponsored by the Utah Department of Environmental Quality