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Diesel Exhaust

What is diesel exhaust?

Diesel exhaust is produced by the combustion (burning) of diesel fuel. The exhaust is a complex mixture of gases, vapours, aerosols, and particulate substances. The exact nature of the exhaust depends on a number of factors including the type of engine, how well serviced/maintained the engine is, type of fuel, speed and load on the engine, and emission control systems.

Diesel exhaust may contain:

  • Carbon (soot)
  • Carbon monoxide
  • Carbon dioxide
  • Oxygen
  • Water vapour
  • Nitrogen
  • Oxides of nitrogen (e.g., nitrogen oxide, nitrogen dioxide)
  • Oxides of sulphur (e.g., sulphur dioxide)
  • Alcohols
  • Aldehydes
  • Ketones
  • Hydrocarbons
  • Polycyclic aromatic hydrocarbons (PAHs)
  • Diesel particulate matter (DPM)

What are the main health concerns?

Short term exposure to diesel exhaust can cause coughing, and irritation of the eyes, nose, throat, and respiratory tract. Breathing in diesel exhaust can cause lung irritation and/or an allergic reaction causing asthma (wheezing and difficult breathing), or making pre-existing asthma worse.

Very high levels can lead to asphyxiation from carbon monoxide poisoning.

Long term exposure may lead to serious health effects. The International Agency for Research on Cancer (IARC), which is part of the World Health Organization (WHO), classified diesel engine exhaust as carcinogenic to humans (Group 1), determining that exposure to diesel exhaust emissions increases the risk for lung cancer and possibly bladder cancer.

Who is at risk of exposure to diesel exhaust?

The most common way individuals are exposed is by breathing air that contains the diesel particulate matter. The fine and ultra fine particles are respirable, which means that the particles can avoid many of the human respiratory system defense mechanisms and enter deeply into the lung.

People may be at risk:

  • In areas where diesel powered vehicles are used such as forklift trucks, railway locomotive, buses, trucks, construction vehicles, farm vehicles.
  • Where diesel exhaust can accumulate, such as warehouses, car/bus depots, ferries/ships, garages, vehicle testing sites, fire stations, mines, or where diesel generators or winch motors are used.
  • In occupations that work in areas where exhaust levels are high or can accumulate, such as police and traffic officers, custom officer/border control booths, ticket/toll booth operators, drivers of diesel vehicles (buses, subway/railway, truck, taxi, forklift, etc.), airline ground crew, farm workers, vehicle maintenance workers, dock/cargo ship workers, miners.

How do I know if exposure to diesel exhaust is an issue?

Conduct a risk assessment to determine the health risks from exposure, and to identify the necessary steps needed to control these risks. See the OSH Answers for more information on how to do a risk assessment.

Questions to investigate include:

  • How likely is exposure?
  • How long is exposure?
  • Who/how many are affected?
  • Have health concerns been reported?
  • Can engines be turned off or idling avoided? Can engines be operated outdoors only?
  • Are the engines in good repair?
  • How exhaust is currently ventilated or removed from the location?
  • Is there visible smoke from the engine?
  • Is soot accumulating in the workplace?
  • What controls are currently in place?
  • How can exposure be reduced or eliminated?

This checklist is not complete. Be sure to investigate all relevant issues for your workplace or situation.

How can exposure to diesel exhaust be controlled?

Various measures can help lower exposure to diesel exhaust. Workplaces may investigate the measures that work best in their situation. Control measures may include:

  • Eliminate by replacing diesel powered engines with electric or other types of power sources (remember to manage any risks introduced by alternative power sources).
  • Use alternate fuels where possible.
  • Use low-emission engines.
  • Use exhaust treatment systems such as filters, catalysts and/or converters, and a corresponding maintenance program.
  • Run engines outdoors (instead of indoors).
  • Maintain engines to help with their efficiency.
  • Maintain the body of the vehicle to make sure that exhaust is not leaking into the cab or passenger area.
  • Modify the layout of the work area to separate the area where people must work and areas where exhaust is generated, such as isolate the generator in a separate, ventilated space, or isolate the worker in a sealed, air conditioned cabin (air filtered) where possible.
  • Ventilate appropriately, such as providing positive pressure ventilation, exhaust extraction devices, inlet and exhaust general (dilution) ventilation, and/or local exhaust (such as tail pipe hose exhaust).
  • Keep openings for border, ticket, toll, or food booths as small as possible and closed as much as possible when there is exposure to exhaust. If booths are in a place where exhaust accumulates, ventilate the booth with fresh air appropriately.
  • Use administrative controls such as:
    • Education and training to workers about the exposure to diesel exhaust and proper use of control measures.
    • Turning off engines whenever possible.
    • Regularly maintaining engines.
    • Reduce the hours of work exposed to exhaust through job rotation and scheduling.
  • Use of personal protective equipment, such as respirators.

Document last updated on August 26, 2016

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