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Take a deep breath. Chances are the air filling your lungs is far from pure even if you live in an eco-conscious area. These days we worry a lot about air pollution, especially those of use who live in large cities. It’s often a driving factor as to why we hit the road — to soak up some peace and quiet, spend time camping in nature and breathe fresh air. But where exactly do you find clean air? It’s natural to assume that less populated areas, beach destinations or mountain towns are go-to locations for anyone looking to escape air pollution, but it turns out it’s far more complicated than that.

There’s a variety of criteria and variables that go into assessing air quality. To further complicate matters, pollution levels can change seasonally and even over a 24-hour time period, which makes defining the term “clean air” challenging. The good news is that these places do exist, you just need to know where to look. Just how we research weather, attractions and gas prices when we plan out road trips, why not add some destinations where fresh air is a consideration? This is especially important if you are driving with a passenger who suffers from asthma or poor respiratory health.

Planning a trip with clean air as a focus can get a little complicated, so we took it upon ourselves to find those locations for you. The study below looks at how clean air is calculated, a snapshot of U.S. pollution and the best and worst cities for finding clean air. Read on to learn more about specific road trips you can take to navigate air pollution in the U.S. — you might even consider renting an electric or hybrid car for the route.

How Clean Air Is Calculated

Before we jump into the best and worst cities for air pollution, it’s important to understand the methodology behind this list. In addition to the two primary gasses (nitrogen and oxygen) that make up the air in our atmosphere, there are smaller amounts of other gases and particles that result in pollution. Five of which are considered major air pollutants and are tracked by the Air Quality Index (AQI):

  • Ground-level ozone
  • Carbon monoxide
  • Sulfur dioxide
  • Nitrogen dioxide
  • Airborne particles

For each of these pollutants, the Environmental Protection Agency (EPA) has established national air quality standards to protect public health. Of the five pollutants on the list, ground-level ozone and airborne particles pose the greatest threat to human health in this country — they’re also two of the main ingredients in smog. For this reason, the best and worst cities on our list are evaluated based on these factors.

pollution factors explained


When gases like nitrogen oxides, hydrocarbons and carbon monoxide are released into the atmosphere, they react to form ozone. While ozone in the stratosphere protects the planet by absorbing UV rays from the sun, ozone at ground level or tropospheric ozone is a harmful air pollutant, because of its effects on people and the environment. It’s also the primary ingredient in smog.

Ground-level ozone is not emitted directly into the air, rather it’s created by chemical reactions between oxides of nitrogen and volatile organic compounds. This happens when pollutants emitted by cars, power plants, industrial boilers, refineries, chemical plants and other sources chemically react in the presence of sunlight.

Particle Pollution

Particle pollution is a mixture of very small liquid and solid particles suspended in the air. These are released through both mechanical and chemical processes, coming from things like construction, road traffic and burning fuels in factories and power plants. Some particles, such as dust, dirt, soot or smoke, are large enough to see with the naked eye. Others are so small they can only be detected using an electron microscope.

While the air we breathe always contains particle pollution, there are dangers in high levels. For this reason, particle pollution is measured on both a year-round and short-term (24 hour) basis — both measurements are factored into the list.

Mapping Air Pollution from Traffic

Now that you understand some of the science behind the calculations, it’s time to take a look at air pollution in the United States. As you might expect, metropolitan cities and their surrounding areas are hot spots for air pollution, but you might be surprised by other areas that didn’t make the cut for clean air.

In collaboration with researchers from the University of Washington, Texas A&M University assistant research professor Haneen Khreis and his team conducted a study that quantified the connection between exposure to traffic pollution and the onset of childhood asthma across 48 U.S. states and the District of Columbia. This data maps areas of the U.S. with the highest and lowest pollution based on the amount of childhood asthma cases around the country.

map of U.S. air pollution

But Khreis and his team aren’t the only ones to suggest that long-term exposure to traffic-related air pollutants is linked to the development of asthma in children and adults. A 2013 study and a much larger meta-analysis in 2017 found consistent connections between this type of pollution and childhood asthma development. Additional studies from the Health Effects Institute and the U.S. Environmental Protection Agency have also come to similar conclusions.

Cleanest Cities

The heat map above gives a shocking overview of pollution across the greater U.S., but you’re most likely interested in how specific cities stack up. Earlier we discussed ground-level ozone and airborne pollution (short and long-term) as top threats to human health. Below, we’ve evaluated cities across the U.S. based on those factors. While it’s possible for a city to make the “cleanest” list by only ranking for two of three pollution factors, only six cities actually make the cut for all three — these are the cleanest cities in the U.S.

Bangor, Maine

Pollution rating Bangor, Maine

Bangor, Maine, is a beautiful northeastern city commonly known for its folkloric lumberjack statue of Paul Bunyan that hints at the city’s former status as a timber hub, but it’s far more than that. Despite the fact that Maine’s air quality as a whole has decreased for ozone pollution, Bangor is one of six cities in the U.S. that actually holds a title for “cleanest cities.”

Burlington-South Burlington, Vermont

Pollution rating Burlington, Vermont

Of all the New England states to make the list, Vermont is consistently considered one of the cleanest states for air quality in the U.S. In fact, Vermont’s Burlington-South Burlington metro area is ranked as the 12th cleanest city for year-round particle pollution in the U.S. and was one of only six cities nationwide to also record zero bad air days for ozone and short-term pollution.

Honolulu, Hawaii

Pollution rating Honolulu, Hawaii

Despite being a major tourist hub and having a population just shy of 1 million people, Honolulu was ranked the fifth-cleanest city in the nation for year-round particle pollution and was also rated “A” for ozone pollution.

Lincoln-Beatrice, Nebraska

pollution rating Beatrice, Nebraska

State capitals are often the busiest cities, buzzing with traffic and pollution. However, this isn’t the case for Nebraska. Lincoln tied for 1st for the cleanest metropolitan area in the country for both ozone and 24-hour particle pollution. It also ranks 179 out of 203 areas for particle pollution.

Palm Bay-Melbourne, Florida

pollution rating palm bay florida

When it comes to smog and soot, Florida skies are pretty clean with several Sunshine State cities ranking among the best in the nation for air quality. Cape Coral, Gainesville and Sarasota all rank high on the list for year-round and short-term particle pollution, but only one metropolitan area made the cut for all three factors — Palm Bay. Tying in first place for the least ground-level ozone and short-term particle pollution, it also ranks 13th for year-round particle pollution.

Wilmington, North Carolina

pollution rating Wilmington, North Carolina

This historic North Carolina port city is best known as a gateway to some of the best Cape Fear Coast beaches, sunken WWII battleships and the home of historic mansion museums. Attractions aside, it’s also a place you want to visit for clean air considering it ranks high on the list for lowest ozone, year-round and short-term particle pollution.

Other Clean Cities

Although not quite as clean as the top six cities, eight other cities are well-worth mentioning and, for that matter, visiting. Each ranked for having the lowest levels of two of the three major pollution factors. The below list including metropolitan areas with no days of spikes in particulate pollution and the lowest concentration of particulate pollution year-round.

Under the Clean Air Act, the EPA set a health standard for particulate matter. Any city with a concentration higher than 12 micrograms per cubic meter exposes their residents to health risks and fails to comply. Each city on this list has a particulate matter pollution count well below that level — however, these cities don’t rank as well for ozone pollution levels.

  • Cape Coral-Fort Myers, FL
  • Elmira-Corning, NY
  • Gainesville-Lake City, FL
  • Grand Island, NE
  • North Port-Sarasota, FL
  • Pittsfield, MA
  • St. George, UT
  • Syracuse-Auburn, NY

Another 19 other cities ranked among the cleanest metropolitan areas for ozone and short-term particle pollution. However, they don’t make the cut for year-round particle pollution counts.

  • Bowling Green-Glasgow, KY
  • Clarksville, TN-KY
  • Eau Claire-Menomonie, WI
  • Fayetteville-Sanford, NC
  • Fayetteville-Springdale, AR
  • Florence, SC
  • Fort Smith, AR-OK
  • Gadsden, AL
  • Greenville-Kinston, NC
  • Houma-Thibodaux, LA
  • Jackson-Vicksburg, MS
  • La Crosse-Onalaska, WI-MN
  • McAllen-Edinburg, TX
  • Monroe-Ruston, LA
  • Roanoke, VA
  • Springfield, MO
  • Tallahassee, FL
  • Tuscaloosa, AL
  • Waterloo-Cedar Falls, IA

The last group includes metropolitan areas that ranked for only low ozone and year-round particle pollution levels. These are the four cities that made the list.

  • Anchorage, AK
  • Bellingham, WA
  • Casper, WY
  • Salinas, CA

Most Polluted Cities

According to, more than four in ten Americans live in counties that have monitored unhealthy ozone and/or particle pollution levels. This equates to roughly 141 million people who live in areas where pollution levels expose residents to major health risks. Some of these health risks cause common issues like wheezing, coughing and shortness of breath.

While most of these are manageable conditions, ozone and particle pollution can create much greater health risks, especially for certain groups of people. If you’re setting off on a road trip with children, elderly family members or anyone with asthma, COPD or other cardiovascular diseases, planning a road trip around air quality might be the key to an enjoyable experience.

4 in 10 Americans live with poor quality air

In fact, some of the worst places for air pollution are also home to bucket-list-worthy sites like Los Angeles and San Francisco. So next time you’re planning a road trip, it might be wise to avoid these areas whenever possible.

By Ozone

#1: Los Angeles-Long Beach, CA
#2: Visalia, CA
#3: Bakersfield, CA
#4: Fresno-Madera-Hanford, CA
#5: Sacramento-Roseville, CA
#6: San Diego-Chula Vista-Carlsbad, CA

By Year-Round Particle Pollution

#1: Fresno-Madera-Hanford, CA
#2: Bakersfield, CA
#3: Fairbanks, AK
#4: Visalia, CA
#5: Los Angeles-Long Beach, CA
#6: San Jose-San Francisco-Oakland, CA

By Short-Term Particle Pollution

#1: Bakersfield, CA
#2: Fresno-Madera-Hanford, CA
#3: Fairbanks, AK
#4: San Jose-San Francisco-Oakland, CA
#5: Missoula, MT
#6: Yakima, WA

Road Trip Routes for the Cleanest Air

You might be convinced to put these clean cities on your must-visit list, but the thing about road trips is that you still have to pass through various metropolitan areas and towns as you make your way to your destination. If you’d like to avoid driving through smog- and traffic-filled locations, then you’ll need to plan a route where there’s relatively clean air along the drive.

Taking into account the three major pollution factors and areas where childhood asthma from traffic-induced air pollution is at a high, we mapped out four routes where you’re most likely to take a breath of fresh air for the majority of the trip. We broke these down by different regions of the country: the northern U.S. and Great Lakes, New England, the Rocky Mountains and Midwest, and the southeastern part of the country.

Route 1: Northern U.S. + Great Lakes

Great Lakes roads

Route 2: New England

New England roads

Route 3: The Rocky Mountains + Midwest

Rocky mountain and midwest roads

Route 4: Southeastern U.S.

southeastern United States road trip

Next time you get the urge to rent a car and hit the road, try one of these routes. As we place more concern on pollution, it’s also important to do your part as a global citizen to help make sure these cities with clean air continue to remain clean. If you can, try driving an electric car. If you drive a traditional gas-powered vehicle, always remember to follow gasoline refueling instructions for efficient vapor recovery, being careful not to spill fuel and always tighten your gas cap securely. Keep your tires properly inflated, engines properly tuned, refuel your car in the evening when it’s cooler and never let your car idle.

Sources: | CityLab | Science Direct | EPA