Particle Pollution Basics

Particle pollution is simply defined as solid particles or liquid droplets that are suspended in air. These can be fine particles (PM2.5) with an aerodynamic diameter of 2.5 microns or less, coarse particles (PM10) with an aerodynamic diameter of 10 microns or less, or Total Suspended Particles (TSP) with an aerodynamic diameter of 100 microns or less. (For a sense of scale, the average human hair is 70 microns in diameter.) In Wisconsin, we monitor coarse and fine particles.

PM2.5

Fine particles may be emitted directly into the atmosphere but are more commonly created by reactions of other pollutants. Fine particles in the air may be consist of hundreds of different chemicals, but sulfur dioxide (SO2), nitrogen oxides (NOx), volatile organic compounds (VOC), and ammonia are the basic building blocks for most of the fine particles or PM2.5 in Wisconsin. Sources of direct PM2.5 emissions include forest fires and wood stoves. Sources of the precursor pollutants that chemically react to form PM2.5 include power plants, industries, and automobiles. Wind can carry fine particles hundreds of miles from its source. PM2.5 levels typically peak in winter but concentrations can also be high in summer.

PM10

Coarse particles usually result from some type of mechanical action such as crushing or grinding, or from wind-blown dust. Sources of coarse particles include roadways and dusty industries. Coarse particles are typically not transported great distances as are fine particles.

TSP

Total Suspended Particles consist of particles typically less than 100 microns in size. When EPA revoked the primary TSP standard in 1987, Wisconsin retained the secondary TSP standard to protect citizens from damage caused by TSP. There are several TSP monitors operated by industrial facilities which are audited by DNR staff to ensure data quality. Currently, there are no areas in Wisconsin that are violating the state secondary TSP standard.

Health Effects

Both coarse and fine particles pose health problems, because they can bypass the body’s natural defense mechanisms and affect both your lungs and your heart. Particles can become lodged in your lungs, and very fine particles may even get into your bloodstream. Scientific studies have linked particle pollution exposure to a variety of health problems such as:

• increased coughing or difficulty breathing
• decreased ability of the lung to transfer oxygen to the lung
• aggravated asthma
• chronic bronchitis
• irregular heartbeat
• nonfatal heart attacks
• premature death in people with heart or lung disease

People with heart or lung diseases, children and older adults are the most likely to be affected by particle pollution exposure. Even if you are healthy, you may experience temporary symptoms from exposure to elevated levels of particle pollution. For more information about asthma, visit Air Quality Information for Health Professionals and EPA’s asthma website [exit DNR].

Environmental Effects

Fine particles scatter light and are the major cause of reduced visibility in the United States. Many fine-particles are also acidic, causing acid rain and making lakes and streams acidic. Deposition of nitrogen-containing particles may change the nutrient balance in lakes and rivers, affecting the diversity of ecosystems or damaging forests or crops. In addition, particle pollution can damage statues, monuments and buildings made of stone and other materials.

For more information

• Current air quality conditions
• EPA’s visibility web site [exit DNR].
• EPA’s acid rain website [exit DNR]

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