Issue 19, June 2006

Environmental Health
Environmental Health is concerned with the diseases and deaths that result from the interaction between people and their environment.  It has more wide ranging implications than occupational health, which is limited to their workplace.  Topical issues of Environmental Health that may affect you, include air pollution and respiratory health, asthma, lead poisoning and human nutrition.

Diesel Exhaust
Overseas research has indicated that occupational exposure to diesel exhaust at high levels in enclosed spaces for long periods of time (e.g. miners) can lead to a 30 % increased risk of lung cancer. A hazard may be presumed to extend to environmental exposure levels.

There are two things about diesel exhaust that can affect your health:

• The particles; and
• The size of the particles.

While diesel is gaining popularity as a fuel for passenger cars due to its fuel economy, the size, number and composition of the particles in the exhaust have raised some concerns. While only some 10% of vehicles use diesel they are responsible for about 80% of fine particles emitted from vehicles.

The size of a particle influences how deeply the particle can penetrate a person’s body:

• The most hazardous particle sizes are known as PM10 – particulate matter with diameters less than 10mm. All fine particles fall within this category and 75% of the PM10 category arises from diesel exhaust fumes.

• There are smaller subsets of PM10. Particles of diameter 2.5mm (PM2.5) can be carried deep into a person's lungs, whereas the larger PM10 particles are more likely to be caught in the nose or upper respiratory tract.

• There is also the ultrafines and nanoparticles with a diameter less than 1mm. These particles represent, by number, up to 99% of particles (but often only 1-2% by mass) and they result in increased deep lung deposition, due to their ultrafine size.

Diesel exhaust is a mixture of at least 450 different chemicals. The particles from the exhaust are coated in a variety of established toxic contaminants; e.g. benzene, formaldehyde, polyaromatic hydrocarbons. Thus the particulate matter from diesel exhaust acts as a microscopic delivery system to carry toxic chemicals inside the body and deep into a person’s lungs.

In a 2002 report, the US EPA concluded that diesel exhaust is a “likely human carcinogen” and a “chronic respiratory hazard to humans”.  Exposure to diesel exhaust has been claimed to be more hazardous than smoking or exposure to passive smoking, yet it is not regulated to the same extent as smoking.

To learn more or keep abreast of air pollution in your city, we recommend you visit your local EPA website.

To read other related articles
Indoor Pollutants
Indoor Air Quality - health effects of VOC's
 

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