Air Sampling Programs for Detecting Asbestos Dust in Mines

Read the U.S. Department of Labor (DOL) and the Mine Safety and Health Administration (MSHA) report about the mineral dust sampling performed to determine the risks to miners. They are routinely exposed to carcinogens such as asbestos.

Mineral dusts are created by the breaking, crushing, grinding, drilling, or general abrasive handling of a solid mineral. For sampling purposes, mineral dusts may be collected as either respirable or total dust.

Respirable dust is a term which describes the aerodynamic diameter of dust particles which can penetrate deeply into the respiratory system, beyond the bronchioles to the alveoli.

Particles which penetrate this deeply into the respiratory system are generally beyond the body's natural clearance mechanisms of cilia and mucous and are more likely to be retained and be harmful.

Respirable dust is also defined as the fraction of the dust which passes a size selector (e.g., cyclone). MSHA's Metal and Nonmetal division defines respirable dust as having the following characteristics:

It is important to remember that, at less than 10 µm in diameter, respirable particles are too small to be seen with the naked eye. For comparison, a human hair is about 50 µm in diameter.

Visible dust may indicate the presence of respirable dust, but a lack of visible dust does not mean that respirable dust is not present.

Total dust is a term which refers to airborne particles that are not selectively collected with regard to their size. Large particles that make up the total dust cloud may overcome the body's natural clearance mechanisms simply by overwhelming those defenses. The smaller particles can be drawn deeply into the respiratory system and retained.

Courtesy of http://www.msha.gov/S&HINFO/OPRSAMP/OPRSAMP.HTM

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