What You Can Do About Car Emissions

Better car maintenance can save money, improve safety, and reduce pollution

Car Emissions — A Problem?

According to the U.S. Environmental Protection Agency (EPA), driving a car is the single most polluting thing that most of us do. Motor vehicles emit millions of tons of pollutants into the air each year. In many urban areas, motor vehicles are the single largest contributor to ground-level ozone, a major component of smog. Ground-level ozone is the most serious air pollution problem in the northeast and mid-Atlantic states. Cars also emit several pollutants classified as toxics, which cause as many as 1,500 cases of cancer in the country each year. Auto emissions also contribute to the environmental problems of acid rain and global warning.

Pollution control measures have drastically reduced emissions per vehicle in the past 20 years. However, during that time the total miles traveled has doubled, resulting in higher levels of air pollutants in many parts of the country.

What Pollutants Do Motor Vehicles Emit and What Are the Health Effects?

Motor vehicles generate three major pollutants: hydrocarbons, nitrogen oxides, and carbon monoxide.

• Hydrocarbons react with nitrogen oxides in the presence of sunlight and elevated temperatures to form ground-level ozone. It can cause eye irritation, coughing, wheezing, and shortness of breath and can lead to permanent lung damage.
• Nitrogen oxides (NOx) also contribute to the formation of ozone and contribute to the formation of acid rain and to water quality problems.
• Carbon monoxide is a colorless, odorless, deadly gas. It reduces the flow of oxygen in the bloodstream and can impair mental functions and visual perception. In urban areas, motor vehicles are responsible for as much as 90 percent of carbon monoxide in the air.

Motor vehicles also emit large amounts of carbon dioxide, which has potential to trap the Earth's heat and cause global warning.

Where Do These Pollutants Come From?

Cars release pollutants from the tailpipe as the result of the fuel combustion process, and from under the hood and throughout the fuel system when heat causes fuel evaporation. Evaporative emissions occur at these times:

• When outside temperatures on hot, sunny days cause a car's fuel to evaporate
• When the hot engine and exhaust system of a running car cause the fuel to become heated
• When the car is shut off and remains hot enough to cause fuel to evaporate
• During refueling, when gasoline vapors escape into the air from the gas tank and the nozzle

The greatest amount of tailpipe pollutants are released during the "cold start" phase, or the first few minutes it takes a car to warm up. Since a car warms up faster when it is moving, drivers are advised to limit warm-up time. Combining trips also decreases motor vehicle emissions since it reduces the number of cold starts.

What Can Motorists Do to Reduce Emissions?

Drivers can help reduce motor vehicle emissions in the following ways:

• Reducing the number of vehicle miles traveled by carpooling, using public transportation, and planning ahead to combine trips. One person using mass transit for an entire year, instead of driving to work, can keep an average of 9.1 pounds of hydrocarbons, 62.5 pounds of carbon monoxide, and 4.9 pounds of nitrogen oxides from being discharged into the air. One full, 40-foot bus also takes 58 cars off the road. A 10 percent nationwide increase in transit ridership would save 135 million gallons of gasoline a year.
• Traveling at moderate, steady speeds (ideally between 35 and 45 miles per hour), and reducing idling time. High speeds result in greater emissions. Idling for more than half a minute burns more gas than it takes to restart the engine. Avoid drive-through windows.
• Keeping vehicles in good running condition. Poorly maintained or malfunctioning vehicles can release as much as 10 times the emissions of a well-maintained one. Motorists should follow the manufacturer's instructions on routine maintenance, such as oil and filter changes. Use an energy saving grade of motor oil (labeled ECII or Energy Conserving II).
  • Don't tamper with the pollution controls and have the vehicle inspected regularly.
  • Keep track of fuel economy. A loss in economy usually means an increase in emissions. Poorly inflated tires can also cause a loss in fuel economy.
  • Watch the exhaust. If it is black, there is too much gas in the mixture and the fuel injection system needs to be checked. If the exhaust is blue, the car is burning oil and releasing excess hydrocarbons.
  • Fix air conditioning leaks immediately.
  • Pay attention to dashboard warning lights. Have the car checked out as soon as possible.
• Not topping off the tank when refueling. Make sure the gas cap fits properly to avoid spills.
• Using clean fuels, when available. Clean fuels include reformulated gasoline, oxygenated gasoline, and alternative fuels. The EPA estimates that reformulated gasoline reduces ozone-forming emissions and toxic air pollutants by 15 to 17 percent. Reformulated gasoline will be required in areas where ozone levels exceed the federal health standard.
  • Oxygenated gasoline is federally mandated in areas that do not meet the federal health standard for carbon monoxide. It contains at least 2.7 percent oxygen on average. It is sold during the colder months of the year when carbon monoxide is more of a problem.
  • Alternatively fueled vehicles run on a variety of fuels, including methanol, ethanol, compress natural gas, and electricity, all of which reduce emissions.
• Going with newer, less polluting cars, such as low-emission and alternatively fueled vehicles. When buying a car:
  • Check the posted fuel-efficiency rating. The greater the efficiency, the lower the carbon dioxide emissions per mile.
  • Older cars pollute more. When buying a used car, have a mechanic check the catalytic converter and other pollution controls to be sure they are working properly. Be sure to keep the vehicle well maintained.
  • Low-emission vehicles, sometimes called "California cars," will increasingly become available over the next several years. These vehicles are different because they have additional emissions control equipment.

How Much Can I Save?

The Federal Highway Administration estimates that it costs people between 22 and 29 cents per mile to operate a car, depending on the size. By ridesharing every day, commuters can save up to $3,000 a year on gas, insurance, parking, and wear and tear on their car. By designating an automobile for pleasure use only, the insurance premiums on that car can go down as much as 20 percent.

It is also estimated that idling and stop-and-go traffic costs motorists 753 million gallons of gasoline a year, or $1,194 per driver in wasted fuel and time. People commuting by computer from home two or three days a week, or working an alternative work week, could save up to three weeks' worth of driving a year.

What Else Is Being Done?

Other measures to control motor vehicle emissions already have been introduced, or will be in the next few years, in areas with severe ozone problems. These include the use of special nozzles at gas pumps to recover gasoline vapors before they can escape into the air; improved inspection and maintenance programs, with more comprehensive testing; and various transportation control measures, including mandatory programs in some areas to reduce the number of motor vehicle trips made by employees and encourage mass transit use.

Even with all the above measures, meeting federal air quality standards will be a close call for some of the more seriously affected areas. Every effort to reduce motor vehicle emissions helps, whether it is carried out by the government, corporations, or individual motorists.