Initial Publication Date: December 13, 2012

Airborne Dust Particles

Author: Stephen Girts

This case study is part of a collection of pages developed by students in the 2012 introductory-level Geology and Human Health course in the Department of Earth Sciences, Montana State University. Learn more about this project.

Airborne dust is particle, or Particulate Matter (PM), pollution, and is one of the most significant air pollutants in Pima County. PM is made up of tiny solid particles or liquid droplets (a fraction of the thickness of a human hair) that float in the air we breathe. Because they are so small, you cannot see individual particles, but you can sometimes see the haze that is formed when millions of particles blur the spread of sunlight.

Hazards Of Airborne Dust Particles

Any type of earth-moving activity or combustion can produce excessive amounts of particles in the air, whether it be from businesses, industry, or individuals.

Examples of the types of dust found in the work environment include:

mineral dusts, such as those containing free crystalline silica (e.g., as quartz), coal and cement dusts;
metallic dusts, such as lead, cadmium, nickel, and beryllium dusts;
other chemical dusts, e.g., many bulk chemicals and pesticides:
organic and vegetable dusts, such as flour, wood, cotton and tea dusts, pollens;
biohazards, such as viable particles, moulds and spores

Dusts are generated not only by work processes, but may also occur naturally, e.g., pollens, volcanic ashes, and sandstorms.

Sources: Where Does It Come From

Airborne Dust Particles can come from pretty much anywhere, any movement or activity can cause a large amount of excess particles in the air.

Disturbed vacant or open lands
Construction and mining activity
Landscaping maintenance activity
Industrial sources
Fires: fireplace, camp, forest

- Charcoal or wood-burning barbecues - Off-road vehicle activity
- Unpaved and paved roads, parking lots - Diesel exhaust

How Airborne Dust Particles Travel The Earth

Airborne Dust Particles can travel through various sources such as soil being lifted up by weather (an Aeolian process), volcanic eruptions, and pollution. Dust comes from arid and dry regions where high velocity winds are able to remove mostly silt-sized material. This includes ares where grazing, ploughing, vehicle use and other human activities have furthered the destabilized the land. Dust in the atmosphere is produced by saltation and sandblasting of sand-sized grains, and it is transported through the troposphere. The airborne dust is considered an aerosol and once in the atmosphere, it can produce strong local radiative forcing.

Bioavailability

Airborne Dust Particles contaminates the biosphere through inhalation by humans and animals, and can also effect crops growing in an area with large amounts of dust particles. When inhaled, the fibers are deposited in air passages and on lung cells.

Impacts On Human Health

Particles can be so small that they pass through the nasal passage and travel to the deepest parts of the lungs and cause damage. To compound the problem, toxic and cancer-causing chemicals can attach themselves to PM yielding much more profound effects. The tiniest of particles can even pass into the bloodstream through the lungs. People most at risk from breathing particle pollution are children, the elderly, and people with respiratory or heart disease. Healthy people can be affected as well, especially outdoor exercisers. Effects of breathing PM for hours, days, or years include:

Breathing difficulties
Respiratory pain
Diminished lung function
Weakened immune systems
Increased hospitalization

pneumonia, asthma, and emphysema - Heart attacks and strokes - Premature death (1-8 years)

Prevention or Mitigation

There are many methods that may be used to control airborne dust.

Limit campfire and fireplace use
Avoid driving on silty or powdering soils
Prevent motor vehicle trespassing
Water at sufficient quantity, frequency, and depth before, during, and after activity (Construction and Mining)