If you’re in the market for a new car…

By Ashley Miller

Read this first

We’re fast approaching car buying season. Now is the perfect time to learn how you can consider air quality when deciding on which make and model to buy.

There are many factors to consider when buying a car. What size is right for you and your family’s needs? Color, cup holders, leather or fabric interior, and gas mileage all make the list. But you can also consider making a better choice for air quality when purchasing your next ride.

Pollution coming from the tailpipes of cars and trucks make up about half of the air pollution along the Wasatch Front. These mobile emissions contribute to both wintertime PM2.5 problems we face during inversions, as well as elevated ozone levels during our hot summer months. Both types of air pollution have been linked to a number of health conditions that impact Utahns.

Check out the window sticker

New and used passenger cars and trucks at dealerships come with a fuel economy and environment sticker on the window called the Monroney Label, named after a United States Senator from Oklahoma. This sticker was created by the EPA to inform consumers about fuel economy and greenhouse gas emissions and other air pollutants coming from the vehicle’s tailpipe. Beginning in 2013, the display of this information was required on all new vehicles being sold in dealerships throughout the country. If you aren’t looking to buy a car from a dealer, don’t fret. You can find this information on

Look for the smog rating and choose the highest number

On that same label you’ll find the vehicle’s smog rating, a number ranging from 1 to 10, 10 being the cleanest. These numbers are based on what’s coming out of the tailpipe. You’ll find a smog rating of 10 on cars that have zero tailpipe emissions, like battery electric models. You can easily compare and contrast models on Choosing a better smog rating means you are buying a car that emits fewer pollutants per mile than one with a lower number.

Look for Tier 3 vehicles

Tier 3 gets mentioned a lot in Utah when air quality is being discussed, and that’s because it makes a big difference in our airshed. The Tier 3 program includes new federal standards for both vehicle emissions equipment and gasoline sulfur content (see CATALYST, October 2017). The Tier 3 program takes a combined approach to reduce the impacts of motor vehicles on air quality and public health. The Tier 3 gasoline standard drops the sulfur content from 30ppm down to 10ppm, which can mean several improvements for air quality. Sulfur is a precursor pollutant to both PM2.5 and ozone pollution. Less coming from the tailpipe means less bad air.

Sulfur also causes trouble for catalytic converters, the equipment designed to remove as much pollution as possible before sending exhaust out the tailpipe. Lower sulfur gasoline means the equipment designed to reduce pollution from the tailpipe works better. Sulfur can build up in a catalytic converter, preventing it from functioning the way the manufacturers intended.

But it’s not just the sulfur content of fuel that the Tier 3 standard addresses. The Tier 3 vehicle emissions standard requires improved emissions control equipment installed in all new vehicles beginning with some model year 2017 cars and trucks. The standard reduces both tailpipe and evaporative emissions from passenger cars, light-duty trucks, medium-duty passenger vehicles and some heavy-duty vehicles. Chances are there are many Tier 3 models on Utah’s lots right now. A Tier 3 vehicle paired with Tier 3 gasoline runs 80% cleaner than Tier 2 models—the equivalent of removing 4 out of 5 cars off Utah’s roads, at least as far as air quality is concerned.

Using the same website, you can easily identify if a new or used car you are looking at buying is a Tier 3 model. The information is available in the same location as the smog rating.

Ashley Miller, J.D., is the vice-chair of Breathe Utah. She is the vice-chair of Utah’s Air Quality Policy Advisory Board and a member of the Salt Lake County Environmental Quality Advisory Commission. She recently became the Senior Government Affairs representative for Marathon Petroleum Corporation.

This article was originally published on August 30, 2019.