The U.S. Environmental Protection Agency (EPA) has identified 21 chemicals in bus and truck exhaust that are known or suspected to cause cancer or other serious health effects. These include chemicals such as benzene, formaldehyde, acetaldehyde and 1,3 butadiene.

Bus emissions also contain other pollutants that have been linked to respiratory diseases and other serious health effects. These pollutants include:

  • Particulate Matter- both black soot you can see and tiny, invisible particles (a fraction of the width of a human hair) that can lodge deep in your lungs. Diesel exhaust contains significant amounts of fine particulate matter. Over 90 percent of diesel engine particulate emissions are highly respirable and carry toxins deep into the lung:
  • Sulfur oxides
  • Nitrogen oxides
  • Carbon monoxide

Health Effects

Adverse health symptoms have been observed even at low levels of atmospheric pollution. For ozone and fine particulate matter, in particular, there does not appear to be a threshold pollution level below which one can be assured of being at no risk. The most sensitive people will experience discomfort at low levels of pollution and are under some degree of stress even if symptoms are not felt or observed. The various constituents of vehicle exhaust, and their photochemical products, are known to either cause or exacerbate a number of ailments. Some of the health effects are:

  • lung cancer
  • cardiovascular disease
  • asthma attacks
  • chronic bronchitis
  • decreased lung function
  • allergies
  • impaired immune system function
  • shortness of breath

Who is at risk?

There are many groups of people at risk from emissions from idling vehicles:

  • Children are more susceptible than healthy adults because their respiratory system are still developing and they breathe at a faster rate.

  • People with existing heart or lung disease, asthma or other respiratory problems.

  • The elderly are also at risk.

Links on This Clean School Bus Site