Gov. Office Status
Skip to main content

Vehicles and Engines


Vehicles such as airplanes, cars, ships, trains, and trucks are powered by internal combustion engines. Vehicles make it much easier to transport goods, materials, and passengers from one place to another. Because vehicles are almost everywhere, we are all exposed to vehicle emissions.

Stationary engines remain in a fixed position, usually to operate generators or other machinery in a building or on a farm. 

See also: Benzene Diesel Ethylene Glycol Methanol Propane Gasoline Toluene Chromium Ozone Carbon Monoxide Particulate Matter Nitrogen Oxides Carbon Dioxide Volatile Organic Compounds (VOCs)

What are Airports and Air Travel?

Airports have runways and buildings for the takeoff, landing, and maintenance of airplanes. They also have facilities for passengers. Air travel occurs in vehicles such as helicopters, airplanes, or anything else that can fly. Airplanes make it possible for thousands of people to travel short and long distances every day. 

Why are Airports and Air Travel a concern?

Airplanes emit several hazardous air pollutants. Aviation industry workers may be exposed to several toxic chemicals. 

The air quality of an airplane cabin is similar to other indoor environments. However, there are also differences. Passengers are in a more densely populated area than usual. Airplane cabins have low humidity and reduced air pressure. Passengers may be exposed to air contaminants such as ozone and allergens.

Passengers may also be exposed to pesticides if pesticide spraying is required in the airplane before it takes off. International flights are more likely to require pesticide spraying. They may use pesticides to prevent spreading plant diseases and pests from one region to another. 

What pollutants are of greatest concern and who is at risk?

Airplanes emit air pollutants such as:

Chemicals used to de-ice airplanes in the winter include propylene glycol and ethylene glycol. These chemicals may run into and contaminate local waterways.

Aviation employees who work in airplane ground service and maintenance may be exposed to gasoline, jet fuel, solvents, glues, degreasers, and coatings. 

Ground service and maintenance employees are most likely to be at risk for exposure to harmful pollutants. Passengers and flight crews may also be at risk.

National Library of Medicine Resources and Databases

  • Traveler's Health

    Curated links to current consumer information on traveler's health. These English and Spanish web resources include background information; related issues; specifics; clinical trials; journal articles; subject matter experts; and targeted resources for children, women, seniors; and patient handouts.

Additional Resources

What are Off-Road Vehicles?

Off-road vehicles are land-based motorized vehicles that do not drive on roads and highways. They are also sometimes called non-road vehicles. Non-road vehicles operate on gasoline, diesel, or propane

On a farm, agricultural off-road vehicles may include tractors, mowers, combines, and trenching machines. Recreational off-road vehicles on a farm may include all-terrain vehicles, dirt bikes, motorized scooters, and snowmobiles. Non-road engines may be used on a farm in generators to create power or pump water for irrigation equipment. 

Off-road vehicles include construction equipment and vehicles such as forklifts, bulldozers, and backhoes. Non-road engines are also used in yard and garden equipment such as lawn mowers, leaf blowers, and chainsaws. 

Why are Off-Road Vehicles a concern?

Off-road vehicles and engines emit almost as much air pollution as highway vehicles. This pollution can contribute to serious human health problems, including cardiovascular disease, asthma, and bronchitis.

What pollutants are of greatest concern and who is at risk?

Pollutants emitted by off-road vehicles include:

People riding in off-road vehicles, or working or living near off-road engines, are at risk for harm from pollutants.

Additional Resources

  • Vehicles and Engines (Environmental Protection Agency)

    Information on vehicles and engines, including importing and exporting, emission regulations, data for compliance and fuel economy, and violations and recalls.

What are Private Vehicles and Commercial Transportation?

Most people drive or ride in a road vehicle every day—a car, truck, bus, or van. Some drive or ride in private cars, others use public transportation. A commercial vehicle is any type of vehicle used for transporting goods, materials, or paying passengers. This includes transportation by air, bus, rail, ship , truck, and van.

Why are Private Vehicles and Commercial Transportation a concern?

Vehicle emissions are a major source of air pollution in the United States. Vehicle pollution comes from burning fuel, either gasoline or diesel. It also comes from evaporating fuel . 


Vehicle pollution contains air toxics. In high concentrations, these pollutants are known or suspected to cause cancer, reproductive problems, birth defects, or other serious health problems.


Vehicles also have major safety concerns. Every year, several million vehicles are involved in accidents that injure or kill thousands of people and damage property.

What pollutants are of greatest concern and who is at risk?

The most common pollutants in vehicle emissions are: 

Air toxics in vehicle emissions include benzene, formaldehyde, and toluene

Vehicles are almost everywhere, exposing us all to vehicle emissions.

National Library of Medicine Resources and Databases

  • Auto Products. Household Products Database

    Search results on auto products from a database that shares information on household products that have been evaluated for their effects on human health.

  • Air Pollution

    Curated links to current consumer health information on the health effects of air pollution. These English and Spanish web resources include background information, prevention and risk factors, related issues, specifics, statistics and research, clinical trials, journal articles, relevant organizations and agencies, and targeted information for children and teenagers.

Additional Resources

What are School Bus?

School buses are the safest way for children to get to school. About 24 million children ride a school bus every day. Most students spend an hour and a half each weekday in a school bus.

Why are School Bus a concern?

Because almost all school buses run on diesel fuel, children are exposed to the pollution in diesel exhaust. Exhaust from buses that idle outside schools can also pollute the air inside the school.

Exposure to diesel exhaust can cause respiratory problems, asthma, allergies, and lung damage. Children are more affected by the harmful effects of air pollution because they breathe at a faster rate than adults and their lungs are still developing.

What pollutants are of greatest concern and who is at risk?

Diesel exhaust contains many harmful air pollutants, including: 

Children can be exposed to diesel exhaust if they ride in a bus or if they play or wait in school bus loading zones where buses are idling with their engines running. 

Additional Resources

Reduce your risk

  • Do you own or operate a vehicle?
  • Do you live or work near a stationary engine?
  • Do you have children who ride a bus to school?
  • Reduce emissions from your vehicle by:
    • Maintaining your car with regular tune-ups. 
    • Following the manufacturer’s maintenance schedule. 
    • Using the recommended motor oil and gasoline.
    • Going easy on the gas pedal and brakes.
  • Drive less. Carpool, bicycle, walk, or use mass transit when possible.
  • Don’t idle the engine.
  • Children can reduce their exposure to diesel exhaust from school buses by sitting toward the front of the bus and keeping a bus window open if the weather allows. 
  • They can also avoid playing outside near a school bus loading zone if buses are there with their engines idling.
Back to top