Childhood Asthma/Diesel Exhaust



Fate and Transport

Exposure Pathway

Methods for Measuring Human Exposure

Strategies for Preventing or Controlling Exposure


Air pollution is defined as those substances in the air at greater than ambient concentrations which have adverse effects on people, animals, plants or inanimate objects.

Sources of Outdoor Air Pollution:
The predominant source of air pollution in the US is the exhaust from the fuel combustion process used to power motor vehicles for transportation.

US Sources of Air Pollution

Distribution and Change over Time
Sources 1970 (%) 1992 (%)
Transportation 69 56
Heat and Power 20 24
Industrial 17 9
Refuse Disposal 3 8
Community and Natural 1 3

In the US, essentially all transportation is powered by gasoline or diesel fuels. Because the burning of diesel fuel results in high levels of particulate matter emission, which is associated with asthma development, the study and reduction of diesel exhaust provides opportunity to impact pediatric asthma.

Diesel fuel is commonly burned in engines powering heavy vehicles such as trucks and buses due to its lower price. However, it also is less efficient in its combustion and results in the production of many irritants and carcinogens. Diesel engine exhaust includes:

  • nitrogen
  • nitrogen compounds
  • carbon dioxide
  • carbon monoxide
  • sulfur compounds
  • low-molecular-weight hydrocarbons
  • oxygen
  • water vapor
  • aldehydes
  • benzene
  • 1,3 butadiene
  • polycyclic aromatic hydrocarbons (PAHs)
  • nitro-PAHs
  • elemental carbon
  • sulfate
  • nitrate

Diesel exhaust emissions contribute to the development and exacerbation of asthma because of both the numerous chemical irritants and the large volume of small particulate matter.


Cleveland Clinic Health System 2002

Robbins, Pathogenesis of Human Disease

Adam Ratner, M.D., Children's Hospital of Philadelphia, Philadelphia, PA