Childhood Asthma/Diesel Exhaust

Introduction

Characteristics

Fate and Transport

Exposure Pathway

Methods for Measuring Human Exposure

Strategies for Preventing or Controlling Exposure

Fate and Transport of the Agents in the Environment

Exhaust is released directly into the air near ground level as the engine powered by diesel fuel is operating.

The particulate matter remains suspended in the air for days.

  • It can build up if weather conditions minimize air movement, such as on calm days with a cloud cover.
  • It can be moved from place to place by wind.
  • I can be washed out of the air by rain.
  • Otherwise it eventually settles to the ground.

The gaseous chemicals react with atmospheric air to create additional noxious compounds.

The concentrations of emissions are highest nearest the source and dissipate with distance. However, these are mobile (non-stationary) sources of emissions and so emission points are widespread.

  • Areas of short-term high concentrations, include vehicle fueling and waiting areas.
  • Urban areas generally and areas along freeways have the next highest concentration of emission due to the volume of traffic burning diesel fuel.
  • Rural areas away from freeways have lower levels although they have emissions carried in the air from other more-polluted areas, and they frequently have other generating sources