We all know that elements dispersed into the air affect the quality of that air. And one of the hot topics, scientifically and politically, has been global warming and what we can do to control the emissions that pollute our environment. But air pollution has been an issue for years.

As far back as 1970, legislation was created to impose strict requirements on states to control emissions. Known as the 1970 Clean Air Act, this legislation had little impact at that time, but the 1990 Clean Air Act tightened the requirements and required that certain states (including Pennsylvania) and counties with serious ozone problems take steps to reduce emissions and to implement an enhanced inspection program. According to the Environmental Protection Agency, nearly 50 percent of all ozone pollution is produced by cars and light trucks.

Each time your car is inspected in Pennsylvania, it must also have an emissions test if it is a 1975 vehicle or newer. In the Philadelphia area, the test is more involved since pollution levels are higher. Cars from 1996 or newer are given an OBD (On Board Diagnostics) test where the emission machine is plugged directly into the car’s computer.

If your car is driven less than 5,000 miles in the one-year period from the exact date of your last state inspection, then you qualify for an emission exemption. Your inspection mechanic can determine if your vehicle qualifies for an exemption.

The car’s emission system keeps the engine running cleanly and efficiently and controls the emissions, exhaust and pollutants using sensors, computerized engine controls and the exhaust components.

The emission system reduces harmful gases and prevents gasoline vapors from escaping. If any of these components is not functioning properly, the “check engine light” may come on, and the vehicle will not pass the state’s emission test.

Since a vehicle can fail an emission test for various reasons, a computer diagnosis may be required, and some repairs, such as replacing a sensor or a more complete tune-up may be necessary.

Even after repairs are completed, the vehicle may need to be driven for approximately 40 or 50 miles in order for the car’s computer to re-learn the memory pre-sets necessary to pass the emission test. This process may require a return trip to the inspection garage to complete the test.

If, when the vehicle returns to the garage, it fails the emission test a second time and you have spent $150 or more toward repairs to the emission system in an attempt to repair the problem, you will qualify for an emission waiver for that year only. This may only be issued by a mechanic who is certified by the state to issue such waivers.

The emission testing procedure in Pennsylvania is complex and costly, which is why the cost of an emission test to the consumer is also high. The standards set by the state are mandated at the federal level and strict audits are conducted at inspection facilities to ensure that testing is done correctly. It is the price we pay to keep our air clean.