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U.S. cities with the cleanest air

Stacker Logo By Hannah Lang of Stacker | Slide 1 of 51: The quality of air inhaled isn't something Americans consciously think about every day, but research from the World Health Organization reveals that 92% of the global population lives in places with unhealthy air quality.

Air pollution can come from transportation, coal-fired power plants, industrial activity, and other human-perpetuated activity as well as natural events like dust storms and wildfires. These invisible pollutants in the air can create smog and acid rain and can lead to serious health problems. Air pollution causes about one in eight deaths worldwide and accounts for many instances of chronic respiratory disease, lung cancer, strokes, and heart attacks. Ozone, which is the main ingredient in smog, can also increase the risk of asthma.

But it's not all bad news. Since the United States enacted the Clean Air Act in 1970, aggregate emissions of the six most common pollutants have dropped by 73%. Between 2000 and 2015, concentrations of contaminants in the U.S. have fallen 40% for fine particle concentrations over 24 hours and 34% for coarse particle concentration. The Clean Air Act also set new emissions standards for cars and trucks, improving the carbon monoxide levels in the air.

The U.S. Environmental Protection Agency collects air quality data for all 193 cities in the country and compiles the results into an annual report. Using data from EPA's 2018 Outdoor Air Quality report, Stacker determined 50 U.S. cities with the cleanest air.

Stacker ranked the top 50 cities by the annual average amount of coarse particulate matter or particles between 2.5 and 10 micrometers in 2018. Particulate matter between 2.5 and 10 micrometers, referred to as "PM10" is considered coarse, and cities with lower average amounts of PM10 have cleaner air.

In the event of a tie, Stacker used the second-highest coarse particulate matter recorded in a city in a 24-hour period in 2018 to exclude unusually low or high outliers. It's important to note that the annual mean amounts of fine inhalable particles smaller than 2.5 micrometers, referred to as PM2.5, were included in the slide data but were not factored into city rankings. Exceptional events data—such as wildfires—was excluded so that rankings would be determined by the typical air quality in each city, and not by unusual events and outliers.

The EPA's National Ambient Air Quality Standards referenced in this piece are 150 ug/m3 for coarse particulate matter (PM10) and 12 ug/m3 for fine particulate matter (PM2.5) over a 24-hour period.

Read on to find out the top 50 U.S. cities that boast the cleanest air.

You may also like: States with the costliest weather events

U.S. cities with the cleanest air

The quality of air inhaled isn't something Americans consciously think about every day, but research from the World Health Organization reveals that 92% of the global population lives in places with unhealthy air quality.

Air pollution can come from transportation, coal-fired power plants, industrial activity, and other human-perpetuated activity as well as natural events like dust storms and wildfires. These invisible pollutants in the air can create smog and acid rain and can lead to serious health problems. Air pollution causes about one in eight deaths worldwide and accounts for many instances of chronic respiratory disease, lung cancer, strokes, and heart attacks. Ozone, which is the main ingredient in smog, can also increase the risk of asthma.

But it's not all bad news. Since the United States enacted the Clean Air Act in 1970, aggregate emissions of the six most common pollutants have dropped by 73%. Between 2000 and 2015, concentrations of contaminants in the U.S. have fallen 40% for fine particle concentrations over 24 hours and 34% for coarse particle concentration. The Clean Air Act also set new emissions standards for cars and trucks, improving the carbon monoxide levels in the air.

The U.S. Environmental Protection Agency collects air quality data for all 193 cities in the country and compiles the results into an annual report. Using data from EPA's 2018 Outdoor Air Quality report, Stacker determined 50 U.S. cities with the cleanest air.

Stacker ranked the top 50 cities by the annual average amount of coarse particulate matter or particles between 2.5 and 10 micrometers in 2018. Particulate matter between 2.5 and 10 micrometers, referred to as "PM10" is considered coarse, and cities with lower average amounts of PM10 have cleaner air.

In the event of a tie, Stacker used the second-highest coarse particulate matter recorded in a city in a 24-hour period in 2018 to exclude unusually low or high outliers. It's important to note that the annual mean amounts of fine inhalable particles smaller than 2.5 micrometers, referred to as PM2.5, were included in the slide data but were not factored into city rankings. Exceptional events data—such as wildfires—was excluded so that rankings would be determined by the typical air quality in each city, and not by unusual events and outliers.

The EPA's National Ambient Air Quality Standards referenced in this piece are 150 ug/m3 for coarse particulate matter (PM10) and 12 ug/m3 for fine particulate matter (PM2.5) over a 24-hour period.

Read on to find out the top 50 U.S. cities that boast the cleanest air.

You may also like: States with the costliest weather events

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