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 EPA'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 .
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. Researchers seem to agree that as precipitation increases, PM2.5 levels will decrease since it "clears" the air
. 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 . More research is needed to accurately quantify to what extent PM2.5 levels will be affected by a changing
PM2.5 Levels Over the National Ambient Air Quality Standard: Percent of Days by Year, Weber County, 2000-2014
Percent reflects the percent of days sampled in the county during the year, not total days of the year.
U.S. Environmental Protection Agency, Air Quality System (AQS).
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 United States' Environmental Protection Agency (EPA)
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 .
How We Calculated the Rates
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
Where applicable, population based on U.S. Census Bureau estimates for July 1 of each year.
Page Content Updated On 04/10/2015,
Published on 04/10/2015
Utah Environmental Public Health Tracking Network, Utah Department of Health, P.O. Box 142104, Salt Lake City, UT 84114-2104, Telephone: 801-538-6191, Fax: 801-538-6564, Email:
The information provided above is from the Utah Department of Health's Center for
Health Data IBIS-PH web site (http://ibis.health.utah.gov). The information published
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