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Which US Cities Have the Highest Air Pollution Levels?

Do you know the air quality in your area? The creation of the Environmental Protection Agency (EPA) led to better monitoring of the air in cities and states across America. The introduction of the Air Quality Index (AQI) also enabled Americans to identify the air quality in their local area easily. The system allowed residents to take precautions on days where the air quality is bad.

Living in the city is a tax on your bodies. The hustle and bustle of commerce and transportation put plenty of pollutants in the air, and it's no surprise to anyone that air quality levels in cities are three times worse than those in rural areas. Some cities are worse than others, and where you choose to live plays a big role in your health.

This post looks at the top ten cities in the world with the highest air pollution levels. We're working off 2019 data for this post, as there isn't anything currently available for 2020. Also, it's important to note that 2020 was a bit of a fluke year for air quality. The global COVID-19 pandemic stopped air travel, limiting the pollution around airports like LAX and John F. Kennedy International.

The stay-at-home orders also had fewer people on the roads, so we fewer vehicle emissions for the year. As the US opens up in the wake of the vaccine rollout, we can expect air pollution levels to return to what we saw in 2019 or worse.

What Causes Air Pollution?

Before we look at the top ten cities in America with the highest air pollution levels, let's unpack the causes of the problem. What causes air pollution? Well, it's a variety of factors. Typically, we can clump these factors into two groups, environmental and industrial pollutants.

Environmental pollutants occur in the air from natural, organic, and inorganic sources. Examples would be mold spores or pollen entering the home or wildfire smoke getting into the air in your neighborhood.

Industrial pollutants are factors like vehicle emissions and ground-level ozone caused by air conditioning systems that lead to smog development. When we look at the data, we see that the western and southwestern regions of the United States experience lower-quality air conditions than other areas of the US.

This geographical predisposition to lower air quality comes from the increased extraction of gas and oil reserves in these areas. The eastern seaboard of the United States is more concerned with reaching clean energy targets, which also impacts improving air quality in these regions.

As long as we continue with the progression of consumerism, our living habits of congregating in cities, and industry, we will continue to see the declining air quality in cities across America and throughout the globe.

What are the Harmful Health Effects of Air Pollution?

Air pollution has many harmful effects inside and outside the home. Outside the house, issues like smog and wildfire smoke can turn the air quality almost unbreathable in certain cities.

Los Angeles was a prime example of this problem.

The vehicle emissions from leaded gas around the city in the 1970s and 80s created huge volumes of smog. The smog would hang over LA, thanks to the cities unique positioning in a natural bowl-like area. The mountains and hills on the sides of the town allowed the smog to fill up like a bowl, reducing air quality dramatically.

Los Angeles residents could barely see a few yards down the street without the rest of the scenery fading into a haze during the height of the problem. However, the introduction of catalytic converters and unleaded gasoline caused a huge impact on reducing smog levels in the city. Some 30-years later, LA still doesn't have great air quality, but it's much better than in the 80s and 90s.

However, smog isn't the only problem in the air. Wildfires ravaged California in 2019 and 2020. The smoke from wildfires gets so bad that the sky turns orange on really bad days when the smoke is out of control.

Going outdoors has a huge impact on your health on these low-quality air days, and prolonged exposure damages your lungs and your health in general. Individuals with allergies find that they experience an increase in the intensity and frequency of allergy attacks on low-quality air days.

People with allergies may experience red, irritated, and watering eyes, skin problems, coughing, wheezing, shortness of breath, dizziness, and fatigue. Staying indoors on low-quality days is critical for anyone suffering from allergies.

Top 10 US Cities with the Highest Air Pollution Levels

The data presented in the 2019 "State of the Air" review by the American Lung Association (ALA) analyzes air quality data from 2015 to 2017. It's important to note that this report indicates air pollution from ozone and short-term particle pollution, and year-round particulate pollution.

Key takeaways from the 2019 report include the following.

The US experienced hotter days on average and increases in particle pollution across most major cities.

Hotter annual temperatures led to the formation of more ground-level ozone in cities, leading to higher incidences of smog creation.

Around 43.4% of Americans reside in towns or counties with unhealthy ozone levels of ozone, particulate pollution, or both. The country's major southwestern and western cities are again at the top of the list for the worst air quality in the United States.

Around half of the top-25 US cities with the highest pollution levels are in California. Once again, LA takes the top spot as the most polluted city in the country, making its run at the top spot for 19 of the last 20-years since record-keeping began.

Here are the most polluted cities in America.


#1 Fresno-Madera, CA

A combination of stable warm weather fronts and the valley walls make it easy for air pollution to collect over this city.


#2 Bakersfield, CA

This farming community sits in a basin, collecting and accumulating air pollutants. As California's oil capital, it also has high levels of industrial emissions.


#3 Fairbanks, AK

This Alaskan town is third overall in both short-term and annual particulate pollution. The community experiences several temperature inversions during the year that occur in the winter. The residents utilize coal and wood-burning stoves in the area, increasing particulate pollution in the air.


#4 Visalia-Porterville-Hanford, CA

Steep mountain valley walls surround this city, trapping air pollution above the residences and business district. The towns of Porterville, Visalia, and Hanford across the San Joaquin Valley have the worst problems in the area.

#5 Los Angeles – Long Beach, CA

As previously mentioned, LA has a reputation for really bad air quality and thick smog. While that's cleared up a lot in recent years, it's still at the top of the listings. Long Beach is a prime area where the flat terrain lets the smog settle and turn the air quality terrible.

#6 San Jose – San Francisco – Oakland, CA

The Bay Area is synonymous with Big Tech and wealth, but it has one of the worst air quality indexes in the world, let alone America. San Jose, Oakland, and San Francisco all experience high levels of particulate and ozone pollution. The combination of wildfires and vehicle emissions makes the air quality terrible across the bay.

#7 Pittsburgh-New Castle-Weirton, PA-OH-WV

Pollution concentrates in valleys and areas where it settles out of the reach of the wind. The valley walls on rivers act like funnels, pushing the air out towards the ocean or up to land areas. Pittsburgh has plenty of waterways funneling pollutants into the city.

#8 El Centro, CA

The hot and dry climate of El Centro contributes to high pollutant levels, and the proximity to Mexico also allows for the drift of industry emissions over the city.

#9 Cleveland-Akron-Canton, OH

The coal-burning plants and heavy vehicle emissions around this industrial hub mean it has some of the country’s worst emissions ratings and lowest air quality levels.

#10 Medford Grants Pass, OR

The wildfires in 2019 had the biggest impact on this city, reducing air quality levels to dangerously low for weeks at a time.

Contact MI&T for an Air Quality Check Of Your Home

It might surprise you to learn that the CDC states the air quality inside the average home is around five times worse than it is outdoors. We already discussed some of the worst places in America for air quality, and the thought of your home being five times worse than it is outdoors is quite concerning.

Many people resort to getting an HVAC or air-conditioning system installed in their homes to help them filter the air. That's a great strategy. However, before you go out and spend money on a fixed or portable air-con system or HVAC, get an air quality test of your home.

An air quality test acts as a baseline for comparison after installing and running your HVAC or air purification system. By getting a report of the air quality in your home, you can identify allergens and toxins causing health issues in your family.

MI&T can also identify natural invaders like mold spores inside your home. We'll hunt down any mold infestation and check all the rooms in your home for the presence of spores. Contact our service center today and book an air inspection for your home.