Focus on Wellness:
The Dangers of Exhaust


Many ATU members in the transit, intercity bus and school bus industries, including bus drivers, fuelers, and cleaners are exposed to diesel exhaust as part of their work. When inhaled, the toxic mixture of gases in diesel exhaust can cause short-term, health problems with immediate impact or long-term health problems that will develop over time.

What are the Effects of Diesel Exhaust?

The small particles in diesel exhaust are readily inhaled and deposited deep into the lung tissue. These particles may cause damage to lung tissue. Pre-existing diseases, such as emphysema, asthma, or heart disease, can be aggravated by diesel exhaust.

Some short-term (or acute) health effects are:

  • Irritation of the eyes, nose, & throat
  • Vomiting
  • Light-headedness
  • Headache
  • Heartburn
  • Numbness
  • Tightness in the chest
  • Tingling in the extremities
  • Wheezing

In addition to these immediate problems, diesel exhaust can cause chronic health problems. The National Institute for Occupational Safety and Health (NIOSH) considers diesel exhaust a potential human carcinogen (cancer-causing substance). It may take many years after the first exposure for diesel-related cancer and other health impacts to develop.

What Can Be Done To Reduce Diesel Exhaust?

ATU members who are regularly exposed to diesel exhaust should consult with their local union officers about the following options for reducing their exposure to this dangerous substance.

Substitution

The best protection against the hazards of diesel exhaust is to eliminate diesel exhaust itself. Many transit systems, intercity bus operators and school districts are replacing diesel engines with engines using cleaner energy sources, including propane, compressed natural gas, and electricity. However, each substitute comes with its own hazard.

Ventilation

If an alternative energy source is not feasible, there are still ways to reduce worker exposure. Diesel exhaust in enclosed areas (such as idling, fueling, maintenance and cleaning areas) can be controlled using both local exhaust ventilation and general ventilation. Local exhaust ventilation is the most effective ventilation system. It removes diesel exhaust before it gets into the air workers breathe. Tailpipe or stack exhaust hoses should be attached to a vehicle running indoors and exhausted to a place, such as the roof, where it will not re-enter the facility. General ventilation involves using roof vents, opening doors and windows, roof fans, floor fans, or other mechanical systems to move air through the work area. General ventilation is not as effective as local exhaust ventilation.

Isolate the Worker from the Exhaust

As many workers as possible should be relocated away from areas containing diesel exhaust. This will prevent needless exposure for workers not directly involved in operating or maintaining diesel-powered vehicles. Operator exposure to diesel exhaust should be controlled by closing the cab windows when vehicles are running. Air conditioned cabs are critical to providing this safeguard year round. While diesel gases can seep into vehicle cabs when the windows are closed, this will limit contact with the particulate matter found in diesel exhaust.

Preventive Maintenance

Following the preventive maintenance practices below can also reduce exposure to diesel exhaust:

  • Maintain and tune-up diesel equipment regularly. Check the exhaust system for leaks
  • Fit vehicles with emission control devices (air cleaners), such as collectors, scrubbers, and ceramic particle traps. Regularly check air cleaners and replace them when they get dirty
  • Fix cracks in vehicles with weather stripping and repair holes in the floor to prevent exhaust from seeping into a vehicle

Personal Protective Equipment

Respirators are the least effective method of controlling exposure to diesel exhaust and should only be used as a last resort. NIOSH has not approved respirators that use air cartridges for protection against diesel exhaust. Only a full face-piece, positive pressure, supplied air respirator can provide adequate protection at high concentrations of diesel exhaust. Respirators must be fitted, cleaned, stored, inspected, and maintained in accordance with Occupational Safety and Health Administration's (OSHA) respirator regulation. In addition, workers must be trained on how to use a respirator properly and receive a medical evaluation to ensure they are physically fit to wear a respirator.

What are the Legal Requirements and Professional Guidelines for Diesel Exhaust Exposure?

In the U.S., Federal OSHA has jurisdiction over private sector workers. Many public sector workers are covered by state OSHA plans. Both federal and state OSHA plans require the inclusion of information on the potential cancer hazards associated with diesel fuel and diesel exhaust on Material Safety Data Sheets (MSDS). Both federal and state OSHA plans also require training in diesel hazards for workers who handle diesel fuel or who may be exposed to diesel exhaust.

Federal and state OSHA plans have permissible exposure limits (PELs) for some components of diesel exhaust, including carbon monoxide, sulfur dioxide, benzene, carbon dioxide, nitrogen dioxide, acrolein, and formaldehyde. OSHA also has a standard on "nuisance" dust that is applicable to the soot in diesel exhaust. As a potential human carcinogen, NIOSH recommends that diesel exhaust exposures be reduced to the lowest feasible limits.

In Canada, employers are also required to provide employees with MSDS, as well as provide education and training to employees on how to safely deal with hazardous substances, such as diesel exhaust. While standards vary from jurisdiction to jurisdiction in Canada, exposure limits are generally comparable to the limits recommended by OSHA or NIOSH.