10 dirtiest U.S. cities in 2024

New Orleans tops our list...find out the other 9

By Susan Meyer

Updated March 11, 2024

Reviewed By Ross Martin

Table of contents:

Cities 1 - 3
Cities 4 - 6
Cities 7 - 10
Methodology

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Everyone wants to live in a clean city. From clear sunsets to better health outcomes, the environment in which you live could have an impact on quality of life. What cities are at the bottom of the list when it comes to environmental cleanliness? We analyzed the 50 most populous cities in the U.S. based on the following criteria:

Number of high ozone days: This data from the American Lung Association calculates the weighted average of high ozone days by calendar quarter and compares it to the 24-hour standard^[1].

Water quality: LawnStarter's water quality ranking assessed 200 U.S. cities and took into account several factors, including water quality violations, basic plumbing and consumer satisfaction^[2].

Carbon dioxide emissions by state: Compiled by the U.S. Energy Information Administration, this shows each state's carbon dioxide emissions by million metric tons^[3].

EV registrations by state: The National Renewable Energy Laboratory tracks the number of electric vehicle registrations in each state, which shows a commitment to cleaner energy in the future^[4].

Using these metrics, The Zebra crunched the numbers to determine the top 10 dirtiest cities in America.

#1: New Orleans, Louisiana

Although New Orleans is one of the country's most unique and charming cities, it holds the top spot on our list of dirtiest cities. Water quality in the Big Easy is one of the lowest on our list. On top of that, there are only 3,000 electric vehicle registrations in Louisiana. Carbon dioxide emissions offset some of these issues by ranking in the middle of the cities we evaluated.

New Orleans by the numbers

Number of high ozone days: Not available
Water quality: 183th place
Carbon dioxide emissions by state: 194.9 million metric tons
EV registrations by state: 3,180

#2: Los Angeles, California

Los Angeles ranks 193rd for water quality in the 200 cities ranked by LawnStarter, making it the worst ranked city among the 50 cities we've evaluated. The city also has one of the highest amounts of ozone days — over 114 each year. As a state, California is tackling its high carbon dioxide emissions thanks to over half a million EVs (which makes sense based on the state's wealth and Tesla presence).

Los Angeles by the numbers

Number of high ozone days: 114.2
Water quality: 193rd place
Carbon dioxide emissions by state: 358.2 million metric tons
EV registrations by state: 563,070

#3: Indianapolis, Indiana

Indianapolis doesn't have ozone day data available, but the city's water quality ranking is quite low. On top of that, the state of Indiana sits in the middle of areas we analyzed for carbon dioxide emissions and EV registrations are just over 10,000.

Indianapolis by the numbers

Number of high ozone days: Not available
Water quality: 163rd place
Carbon dioxide emissions by state: 176.1 million metric tons
EV registrations by state: 10,360

#4: Pittsburgh, Pennsylvania

Pittsburgh is the next city on our list of dirtiest places. Water quality is an issue here, ranking one of the lowest of the places we evaluated. Pennsylvania's carbon dioxide emissions are also on the higher side, at over 218 million metric tons. Electric vehicles are somewhat common, with the state ranking in the middle compared to the rest of our list.

Pittsburgh by the numbers

Number of high ozone days: Not available
Water quality: 178th place
Carbon dioxide emissions by state: 218.7 million metric tons
EV registrations by state: 26,770

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#5: Riverside, California

Riverside stands out on this list as the city with the largest number of high ozone days. Additionally, water quality is one of the 10 worst out of the areas we looked at. California does have a high concentration of electric vehicles. But as we saw with Los Angeles, the state also has a huge output of carbon dioxide emissions (likely because of its large population).

Riverside by the numbers

Number of high ozone days: 133.3
Water quality: 167th place
Carbon dioxide emissions by state: 358.2 million metric tons
EV registrations by state: 563,070

#6: Houston, Texas (tied)

Houston's water quality has a low ranking compared to other cities. And on top of that, Texas has more carbon dioxide emissions than any other state on our list. The Federal Reserve Bank of Dallas contributes this to a large population that's reliant on cars, as well as the state's energy intensive manufacturing^[5].

Houston by the numbers

Number of high ozone days: Not available
Water quality: 171st place
Carbon dioxide emissions by state: 683.2 million metric tons
EV registrations by state: 80,900

#7: Philadelphia, Pennsylvania (tied)

Our study came up with a three-way tie for seventh place on our list. Philadelphia placed in the top 10 for the number of high ozone days, but it's worth noting that its average 6.8 days is much less than the highest on our list: Riverside's 133 days. As we saw with Pittsburgh, the state of Pennsylvania emits 218.7 million metric tons per year and has an average number of EV registrations.

Philadelphia by the numbers

Number of high ozone days: 6.8
Water quality: 146th place
Carbon dioxide emissions by state: 218.7 million metric tons
EV registrations by state: 26,770

#7: Dallas, Texas (tied)

Dallas has a relatively high number of ozone days compared to most cities on our list, but still considerably lower than cities in California. As discussed with Houston, there is a high amount of carbon dioxide emission in Texas, although it's worth noting that the state is a leader in wind energy, which accounts for 21% of the state's power^[6].

Dallas by the numbers

Number of high ozone days: 8.5
Water quality: 136th place
Carbon dioxide emissions by state: 683.2 million metric tons
EV registrations by state: 80,900

#7: San Diego, California (tied)

Our final spot for seventh place is San Diego. The city has nearly 30 high ozone days a year (which is still relatively low compared to Riverside's 133). Water quality is also lower than most other cities in the U.S., coming in 166th place overall (the 10th worst on our own list of 50 cities).

San Diego by the numbers

Number of high ozone days: 29.3
Water quality: 166th place
Carbon dioxide emissions by state: 358.2 million metric tons
EV registrations by state: 563,070

#10: Detroit, Michigan

Detroit has the sixth lowest water quality ranking out of the 50 cities we evaluated. Carbon dioxide emissions in Michigan of about 160 million metric tons are average compared to other states. Electric vehicle registrations are relatively low, although the Detroit area is set to open a new EV manufacturing factory^[7].

Detroit by the numbers

Number of high ozone days: Not available
Water quality: 175th place
Carbon dioxide emissions by state: 159.2 million metric tons
EV registrations by state: 21,200

The Zebra pulled four data points to analyze the top 50 MSAs (by population) in the U.S. related to environmental cleanliness:

Number of high ozone days (American Lung Association)

Water quality (LawnStarter)

Carbon dioxide emissions by state (U.S. Energy Information Administration)
EV registrations by state (National Renewable Energy Laboratory)

MSA data was used where applicable, and we sometimes substituted city or state data as necessary.

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