Car Emission Facts

Most cars on the road emit a lot of harmful gases into our environment. It's more of a cumulative problem than an individual problem. Because so many people all over the world drive their cars every day, the cumulative effect is rather large. Once you know a little more about what these harmful emissions are, you'll be better equipped to make good decisions about future car purchases.

Evaporative Emissions

Even when your car's not running, it's still emitting harmful gases into the environment. Warmer weather helps create more gasoline vapors, which then escape from the confines of your car's gas tank and engine. When you've turned the car off after driving, your hot engine will continue to emit gas vapors as it cools down. When you stop to put gas in your car, the liquid gas displaces even more gas vapors that have built up in your tank, forcing them out into the environment.

While driving, your car may also emit these types of emissions. It's the nature of liquid gasoline and heat, and these vapors may come from both your exhaust and your running engine.

Exhaust Emissions

VOCs (volatile organic compounds), also known as hydrocarbons, cause an ozone layer to form on the ground. This can cause eye and breathing problems in humans and is also thought to be carcinogenic, according to Environmental Protection Agency research.

Carbon monoxide (CO) is another serious byproduct of modern combustion engine exhaust. The EPA advises that heart disease sufferers should be particularly wary of this gas, as it interferes with proper levels of oxygen flowing through your bloodstream.

Carbon dioxide (CO2) is a greenhouse gas, which is thought by the EPA to contribute to our global warming problem as of August 2009.

Also according to the EPA, nitrous oxides (NOx) not only contribute to our ozone and smog problems, but they also help to precipitate acid rain.

Emissions Change at Various Speeds

While your car is likely emitting certain amounts of all of these gases most of the time, rates of emission change depending on speed. NOx emissions are higher when you drive at higher speeds, but CO and VOCs are actually lower.

On-Board Diagnostics

If your car is a 1996 model or newer, the 1990 Clean Air Act mandates that all auto manufacturers have an on-board diagnostics computer (OBD) installed in every new car sold. If your state has mandatory EPA emissions testing, both your OBD readings and your tailpipe emissions may be evaluated. OBD computers monitor many essential engine functions, including monitoring your levels of exhaust emissions. They can warn you of problems before they become serious and expensive.

Reducing Emissions

Monitor your car's OBD computer and investigate thoroughly if it causes your "check engine" light to come on. Drive your car as infrequently as possible, and drive as fuel-efficiently as possible. Only use air conditioning and heat when it's absolutely necessary. If you're going to idle your car for longer than 30 seconds, such as at a railroad crossing while waiting for a freight train to go by, shut your engine off. Shutting your engine off and restarting it bears a lower emissions cost than allowing it to sit idle---and it has the pleasant side effect of saving you gas money, too.

References

• Car and Light Truck Emissions
• Vehicle Emissions
• Air Emissions Definitions

Resources

• Green Vehicle Guide