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Indicator Report - Air Quality: Particulate Matter (PM2.5)

Why Is This Important?

PM2.5 can get deep inside the lungs and cause a variety of symptoms, such as painful breathing, chest tightness, headache, and coughing. PM2.5 can exacerbate respiratory infections, trigger asthma attacks and symptoms, and cause temporary reductions in lung capacity. Respiratory symptoms are more likely to occur when PM2.5 levels exceed the Environmental Protection Agency's standard, but are possible when PM2.5 levels are below the standard, especially in sensitive populations. PM2.5 has been found in some studies to be associated with an increased risk of chronic lung disease (2).

In addition to these adverse outcomes, PM2.5 can influence the environment in ways that will eventually affect human health. Fine particles cause haze which reduces visibility. The long-term effects of PM2.5, which settles in the soil, natural water sources, forests, and agricultural areas, are still to be determined.

Whether or not climate change has an effect on PM2.5 concentration has yet to be determined. However, as temperatures increase, PM2.5 concentration has been shown to increase in the United States, but this is not the general consensus of the scientific community. However, researchers seem to agree that as precipitation increases, PM2.5 levels will decrease since it "clears" the air (3). If precipitation events are seen to increase with climate change, it is reasonable to conclude that PM2.5 levels may decrease. PM2.5 concentrations could also be affected by air stagnation events (i.e., inversions). If air stagnation events increase in frequency with climate change, PM2.5 levels are likely to rise because these events trap the pollution at the Earth's surface (3). More research is needed to accurately quantify to what extent PM2.5 levels will be affected by a changing climate.

PM2.5 Levels Over the National Ambient Air Quality Standard: Person-days by Year, Washington County, 2001-2011

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Data Sources

U.S. Environmental Protection Agency, Air Quality System (AQS). Population Estimates: National Center for Health Statistics (NCHS) through a collaborative agreement with the U.S. Census Bureau.

Other Views


Particulate matter that measures 2.5 micrometers in diameter or less is often called PM2.5. Particulate matter 10 (PM10) measures one-seventh the width of a strand of human hair, so one can imagine just how small PM2.5 really is. PM2.5 is composed of metals, allergens, nitrates, sulfates, organic chemicals, soil, and dust that are emitted from sources such as combustion products, soot from fireplaces, and blowing dust from construction sites and agricultural activities. PM2.5 levels are generally higher during the winter months due to weather, temperature, and inversions. The Environmental Protection Agency's PM2.5 standard states that daily averaged PM2.5 levels should not exceed 35 micrograms per cubic meter, while annually averaged PM2.5 levels should not exceed 12 micrograms per cubic meter (1).

How We Calculated the Rates

Numerator: This indicator report contains the following views: 1. Percent of days above the National Ambient Air Quality Standards (NAAQS) 2. Number of person-days above the NAAQS 3. Average annual ambient concentrations of PM2.5 4. Percent of population living in counties exceeding NAAQS
Denominator: Where applicable, population based on U.S. Census Bureau estimates for July 1 of each year.

Page Content Updated On 10/18/2013, Published on 10/31/2013
The information provided above is from the Utah Department of Health's Center for Health Data IBIS-PH web site ( The information published on this website may be reproduced without permission. Please use the following citation: "Retrieved Thu, 24 April 2014 14:50:05 from Utah Department of Health, Center for Health Data, Indicator-Based Information System for Public Health Web site:".

Content updated: Tue, 19 Nov 2013 23:09:23 MST