&EPA United States Environmental Protection Agency- Office of Air and Radiation 6401 April 1997 ;EPA #420-F-97-004a The Drive to An Introduction to Enhanced Vehicle Emission Testing ------- About the Emission Testing Law In 1990, Congress amended the Clean Air Act to require states to Implement vehicle inspection and maintenance (I/M) pro- grams. Highly populated areas that fail to meet air quality standards must implement either a "basic" or "enhanced" I/M pro- gram, depending on the level of pollution. The Act also requires additional controls on stationary sources (i.e., power plants) of air pollution, so everyone contributes to solving this important national problem. uying a car or truck is one of the biggest investments you make. To protect that investment, you must keep your vehicle in good working order. An important way to do that is to have your vehicle's exhaust emissions tested. Besides reducing air pollution, emission testing can help improve fuel economy and extend the life of your vehicle. Emissions and Your Vehicle - High emission levels do more than pollute the air. They are symptoms of poor engine performance, which can cause decreased fuel efficiency and may signal possible engine troubles down the road. You can extend the life of your vehicle by following the manufacturers maintenance recommendations. Regular maintenance generally can help prevent many emission problems from developing. If emission problems do occur, studies show that you can improve your vehicles fuel efficiency by an aver- age of 6% to 13% by having die'problem repaired. This could mean a savings of $40 to $90 per vehicle every year. In addition to lowering fuel costs and increasing your engines efficiency, high-tech test-only emission testing is the most effective, least expensive way to identify polluting vehicles, which are die largest single source of air pollution in the United States. ------- Emissions and the Environment " How Do Emission Tests "Work? *- By identifying vehicles that pollute, emission testing helps reduce risks to our health and the environment. It specifically works to reduce emissions of two major pollutants — carbon monoxide and ozone. > Carbon monoxide (CO) is the deadliest com- ponent of air pollution. It is a colorless, odorless gas that results from incomplete combustion of fuel. CO goes direcdy from a vehicles tailpipe into the air we breathe. It enters the bloodstream through the lungs and forms a compound that inhibits the bloods capacity to carry oxygen to die brain and tissues. This poisonous gas affects the elderly, infants, people with heart and respiratory disease, and even healthy individuals when they exercise. Acute exposure to CO can cause brain damage. Motor vehicles typically contribute 90% of the carbon monoxide pollution in urban areas. >" Another toxic component of air pollution is ozone, formed when hydrocarbons (HCs) and oxides of nitrogen (NOx) combine with sunlight. Both HCs and NOx are emitted from vehicles. In die upper atmosphere, ozone benefits life by filter- ing out ultraviolet radiation from die sun. At ground level, however, ozone can be damaging to plants, ani- mals, and human tissue. Ozone is also a severe irri- tant that causes the choking, coughing, and stinging eyes associated with smog. High ozone concentra- tions can present serious problems for children, the elderly, and diose with existing lung conditions. In typical urban areas, as much as one-half or more of these pollutants come from cars, trucks and buses. "**" Emission tests check the gases your exhaust system releases and diagnose how well the entire system- is working. They compare your actual emissions to die allowable standards for your vehicle model year and type. There are two types of inspection and maintenance (I/M) testing programs — basic and enhanced. Which test is required for your vehicle depends on die level of air pollution in your area. Since most motorists are familiar with basic I/M programs begun in the 1980s, this brochure focuses on enhanced I/M. Enhanced I/M refers to performance-based emission control initiatives selected by each state to meet enhanced performance standards in reducing air pollution locally. There are several advanced technologies which can be used to evaluate overall engine performance. These high-tech, mass-based transient tests are currendy used in areas where pollution is more severe. The tests are very effective because they simulate actual driving conditions (including idling, acceleration, various speeds, and load levels) allowing emissions to be calcu- lated more realistically. In addition, the sophistication of this technology reduces or eliminates false passes and false failures common in I/M testing. A trained inspector, experienced in testing proce- dures and proper handling of vehicles, drives the vehicle onto a dynamometer (a vehicle treadmill) and performs some or all of the following tests: >• An exhaust test accurately measures, under real-world driving conditions, the amount of pol- ------- lutants coming through a vehicles tailpipe and compares that amount to the allowable standards. In general, tests take anywhere from 30 seconds to four minutes, or about two minutes. >• A purge test determines whether the gasoline vapors are properly captured from the fuel tank and charcoal canister and routed to the engine where they are burned as fuel. This is essential for pollution control and good fuel economy. This test is performed during die exhaust test. >• A pressure test checks the vehicles evaporative emission control system for a proper seal. X An on-board diagnostic (OBD) test. Engine and emission control systems on todays vehicles are controlled by on-board computers. OBD computers monitor these systems and store codes when a problem is found so inspection or repair technicians can access these codes. The OBD test checks a log for any emission control problems recorded by the computer. >-A visual check of major emission control components. In addition to IM240, there are other tests, inspec- tions, and measures that states may select in develop- ing their programs to fit their local needs. By identifying vehicles that pollute, emission testing helps reduce risks to our health and the environment. It specifically works to reduce emissions of two major pollutants — carbon monoxide and ozone. The Future of Emission Testing - Only by testing can we be sure that a vehicle's emission control system is working properly. Today's tests are geared toward identifying emission control issues and having them repaired. Emission tests and other visual inspections rely on sophisticat- ed computer technology both at the testing site to recognize if and how the car contributes to the pollution problem and at the repair facility where diagnostic equipment helps die technician isolate the cause so that it can be eliminated. New technology, however, promises to make testing even easier. For instance, all new cars and trucks are equipped with OBD computers that monitor all die systems in a vehicle. OBD checks, if found to be effective, may replace other kinds of tests in the future. Advanced technology in modern vehicles can gready improve the quality of our air, but only if the engine is functioning properly. As vehicle owners take personal responsibility to maintain their vehicles and verify their engine performance through emission testing, America's #1 source of air pollution will be put in check. A well-maintained car will last longer, cost less to operate, and be part of the solution to healthier, cleaner air. ------- |