Emissions testing is mandatory in many US urban and suburban areas to reduce pollutants harmful to the environment and human safety. Vehicle manufacturers use various systems to monitor emissions, and emissions testing has been in place since the 1960s.
Emissions testing checks the levels of hazardous materials that escape from a combustion engine motor vehicle. In many areas of the United States, especially urban or suburban areas, emissions testing is mandatory. The goal of mandatory emissions testing is to reduce pollutants harmful to the environment, with a focus on improving air quality.
Although emissions from new vehicles have been significantly reduced in recent decades, the threat to the environment and human safety remains a major concern. There are no federally mandated consumer emissions tests. The Environmental Protection Agency (EPA) works in partnership with individual state agencies to recommend and regulate emissions testing.
Standard combustion engine automobiles release a variety of pollutants into the environment, some of which are harmful to humans and other living creatures. Hydrocarbons are unburned fuels that create smog and potentially contribute to the growth of cancer. Particulates are byproducts of fuel soot that can cause respiratory problems. Carbon monoxide is known to reduce blood flow throughout the body and is especially dangerous for those with heart disease.
Other pollutants also threaten the environment. Carbon dioxide is a greenhouse gas believed to contribute to global warming. Nitrous oxide causes smog and acid rain.
There are several ways vehicle manufacturers monitor emissions to pass emissions tests. A catalytic converter converts harmful emissions into less harmful ones before releasing them from the vehicle. Exhaust gas recirculation (EGR) valves and positive crankcase ventilation (PCV) systems come from different areas of the vehicle, but function very similarly. Both filter vapors into the combustion chamber to cool the chamber and prevent excess pollutants that can be caused by too much heat.
Two of the systems specifically deal with the dangerous vapors created by the evaporation of gasoline. With evaporation controls, a carbon canister traps gas evaporation vapors that would otherwise be released into the air. The air injection releases air into the exhaust chamber to cause combustion, which in turn destroys the unburnt fuel, thus preventing the creation of evaporative vapor.
Emissions testing was the result of decades of research into the dangers of vehicle emissions and the struggle to raise public awareness about them. The first studies on the contribution of motor vehicles to environmental degradation date back to the 1950s. By the 1960s, many automakers had already begun self-regulating emissions on their vehicles. The first emissions test was done in California in the 1960s. Today, most urban areas require testing, a fact that has forced manufacturers to come up with new ways to reduce emissions to stay competitive.
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