In 2011, more than 10 million people lived in the three areas of Texas that do not meet EPA standards for air quality. These "nonattainment" areas are Houston/Galveston, Dallas/Fort Worth, and El Paso.

Several more areas of the state are classified as "near-nonattainment" because they are close to exceeding federal air quality standards: Austin, San Antonio, Victoria, Tyler/Longview, Beaumont/Port Arthur, and Corpus Christi. U.S. EPA, Green Book, 2011

Emissions from cars and trucks are responsible for half of all the air pollution in some parts of our state.

What is Ozone?

Ozone is necessary for life on earth, as we know it. In its proper place in the stratosphere (up high), ozone helps protect the earth from the sun's harmful rays. But on the earth's surface (down low), ozone is the major ingredient of smog, a problem plaguing many of our cities in Texas.

Ground-level ozone is formed when nitrogen oxides (NOx) and volatile organic compounds (VOCs) come together in the presence of heat and sunlight. NOx is found in the exhaust from motor vehicles and other sources of combustion or industrial processes. VOCs come from a number of sources, including fuel combustion and evaporation. EPA Fact Sheet, 1993 and EPA Website.

Other Vehicle-Related Pollutants

Carbon monoxide (CO) is a colorless, odorless, poisonous gas. It results from incomplete combustion of fuel. Improperly tuned vehicle engines are likely to have higher carbon monoxide emissions. EPA Website.

Nationwide, about 60 percent of CO emissions come from motor vehicle exhaust, while in urban areas the percentage of CO emissions produced by cars and trucks increases to 95 percent. EPA Website Carbon Monoxide Summary and EPA Website AIRNow.

Fine airborne particulates are produced during fuel combustion or as a result of reactions of gases such as sulfur dioxide, nitrogen oxides, and volatile organic compounds.

What can you do to reduce emissions and Drive Clean?

Maintain Your Vehicle

Proper vehicle care that follows manufacturers' recommended maintenance guidelines reduces emissions, extends the vehicle's life, increases its resale value, and optimizes its fuel economy.

Fixing a car that is noticeably out of tune or has failed an emissions test can improve its gas mileage by an average of 4 percent. Fixing a serious maintenance problem, such as a faulty oxygen sensor, can improve your mileage by as much as 40 percent. U.S. Department of Energy and EPA Website

Checking and replacing a clogged air filter can improve your car's gas mileage by as much as 10 percent.

Keeping tires properly inflated can improve gas mileage by around 3.3 percent.

When fueling, avoid "topping off" the tank – that is, dispensing a little more gasoline into the tank after the pump automatically clicks off – because it allow more fuel to escape as vapor and increases the possibility of spilling fuel on the ground where it will evaporate into the air. EPA Fact Sheet, 1994 and the Maryland Department of the Environment.

Avoid Idling

Extended idling is not an effective way to "warm up" a modern vehicle's engine. The best way to warm up the engine is to drive the vehicle. For the computer-controlled, fuel-injected engines found in most modern vehicles, no more than 30 seconds of idling should be needed; this is enough to circulate oil through the engine. Natural Resources Canada and Office of Energy Efficiency, Canada.

Idling for long periods of time, such as while waiting in line at a drive-through, can burn more gasoline and create more polluting emissions than turning off and then re-starting the vehicle. EPA Report, 1994.

Drive a Cleaner Vehicle

The Green Vehicle Guide on the EPA website provides information about the fuel efficiency and emissions ratings of new vehicles.

Drive the Speed Limit

A vehicle burns more gas and emits more pollution when quickly accelerated, driven fast, climbing a grade, carrying extra weight, or the engine is being revved. EPA Fact Sheet, 1994.

Drive Less

You can drive less by combining trips, carpooling, using public transit, and choosing clean transportation alternatives such as biking or walking. EPA Fact Sheet, 1994.

Clean Air Tips