30 of America's most polluted cities

30 of America’s most polluted cities

Larry Holzwarth - July 17, 2021

In the 19th century people living in America’s largest cities believed the air carried the contagious diseases which ravaged them in the warm months. Today, the residents of metropolitan areas endure air and water often detrimental to their health. Often they don’t know it, despite air quality reports becoming a part of weather forecasts on television, radio, and social media. Unhealthy industrial pollution, pollen, and mold, contribute to respiratory problems, even in those who enjoy good health. The problem is generally worse in southern cities where heat and humidity holds airborne contaminants for extended periods, creating public health crises. Here are the most polluted cities in the United States.

Cincinnati’s particulate pollution is largely from construction sites. Scripps

30. Cincinnati, Ohio

Cincinnati’s air quality is poor for most of the year, though pollution from heavy industry remains relatively low. The main sources of pollution come from coal-fired power plants and the automobile. Cincinnati lacks high-occupancy vehicle (HOV) lanes on its major roads. Daily heavy traffic adds tons of particulates to the air, often still and humid in the summer months. Heavy construction adds dust and grime, contributing to the low air quality which creates a haze over the city and its suburbs during the warm months of the summer. The city’s air presents no health problems to residents and visitors, according to officials, but expect days of poor air quality in the Queen City, especially in high summer.

Knoxville suffers from heavy air and water pollution. Knoxville Mercury

29. Knoxville, Tennessee

Set deep in a valley, amid high mountains, pollution from Knoxville’s industry remains trapped over the city for days and even weeks. Code Orange air quality alerts, assigned during periods of unhealthy air quality for sensitive persons, occur frequently, especially during the warm months. Prime factors contributing to the poor air quality include the thousands of vehicles which travel through the junction of I-75 and I-40 daily. Calm winds keep the pollutants trapped over the area. Heavy industry and power plants burning coal add to the mix. Air quality in Knoxville has improved, but it remains high on the list of polluted regions in the United States.

Shreveport is a heavily littered and polluted city, including its air, water and grounds. KSLA

28. Shreveport, Louisiana

Like with the rest of the State of Louisiana, trash and litter decorates the city of Shreveport. Locally, waterways and the air present a similar state. High levels of ozone predominate, creating risk factors for children and those over the age of 65. Hot, humid days and nights exacerbate the problem during the summer. Smog presents high risks for those suffering from asthma, COPD, and coronary heart disease. The World Health Organization listed Shreveport as very high for water pollution, and high for noise and light pollution, though on most days the quality of the air ranks high compared to similarly sized American cities.

Wisconsin conservatives oppose the Clean Air Act and attempts to regulate pollution of the air and waterways. Wisconsin Public Radio

27. Sheboygan, Wisconsin

When the American Lung Association gave Sheboygan failing grades for air pollution in 2018, local officials sprang into action. Though not to take steps to improve air quality. Instead, measures were introduced to change the measurement and recording of air quality. According to the Wisconsin Department of Natural Resources, poor air quality came from outside the state’s borders. They argued the pollutants traveled to Wisconsin from sources in Indiana and Illinois. They demanded a change to air monitoring locations, and for non-enforcement of EPA regulations on Sheboygan County industries and businesses designed to create cleaner air.

Air quality in Hartford is among the worst of New England’s cities. Hartford Business Journal

26. Hartford, Connecticut

Although it has shown some improvement in the 21st century, Hartford continues to rank among the worst cities in the eastern United States for ozone pollution. In 2018 particulate pollution in the air increased in Hartford County. Primary contributors included coal and wood fires, as well as diesel emissions. Officials with the Department of Energy claim up to 90% of Connecticut’s air pollution originates in other states to the west and south. Prevailing winds carries pollution over the Connecticut Valley, where it stalls during hot summer days. Connecticut has the dubious distinction of presenting the highest rates of asthma in the United States, by a significant margin.

Houston and other Texas cities are heavily polluted due in part to non-compliance with clean air regulations. Houston Chronicle

25. Houston, Texas

Beginning in 1999, Houston’s overall air quality improved steadily for two decades. In 2019 it took a step backwards. The nation’s fourth largest city in terms of population is among the top ten for ozone pollution – smog. The number of “bad air days”, which had been in decline, jumped in 2018 and 2019, in part due to extended heat waves of greater intensity. Over 6,000 children in the Houston Independent School District are known to suffer from asthma, a condition worsened by the polluted air. According to Houston’s Chief Environmental Science Officer, more than 60% of the ozone pollution affecting Houston comes from automobiles.

The number of unhealthy air days in Indianapolis has been increasing annually since 2016. Indiana Public Media

24. Indianapolis, Indiana

In 2017 Indianapolis recorded 4 bad air days, attributed to ozone pollution. In 2018 the city endured ten. Particle pollution – soot and particulates from burning coal, diesel fuel, and wood, improved, but only slightly. Indianapolis is a city based on the automobile. In 2019, the city received a grade of F for ozone pollution, and a D for particle pollution. Hot weather increases the emissions from cars forming ozone pollution, and climate change ensures an increase in hotter days. During the summer months air quality in Indianapolis drops significantly, with automobiles and trucks the leading contributors.

Atlanta’s maze of roadways and reliance on cars gives it some of the worst air pollution in the United States. Atlanta Journal-Constitution

23. Atlanta, Georgia

The single largest contributor to the formation of ozone pollution are nitrogen oxides. In Atlanta, tailpipe emissions from cars and trucks accounts for most of the nitrogen oxides polluting the air. Though other cities face longer commuting times, Atlantans average over 34 miles per person per day in their automobiles. Often their trips are lengthened in terms of time, thanks to gridlocked traffic. According to the Georgia Department of Natural Resources, Atlanta ranked second among American cities for pollution from vehicles in 2005. Urban sprawl contributes to the commuting time and the tailpipe emissions polluting the Georgia air.

Automobiles are the primary source of the heavily polluted air in the nation’s capital. Associated Press

22. Washington, DC

The nation’s capital is notorious for heavy automobile traffic on its beltways and major roads. Commuters from the Maryland and Virginia suburbs endure gridlocked conditions daily. During the summer months traffic jams are frequent during the hottest time of day. In 2018 the Washington Metro area received an F for ozone pollution, after several years of D grades. Nearly 10 million people in the region (including Baltimore) are considered at risk for respiratory problems during bad air days. The DC area scores well for particle pollution, with little heavy industry in the region producing the soot and grime troubling other eastern cities.

Unhealthy air days in New York Increased in number since 2016. Public Radio International

21. New York, New York

People don’t usually think of the extensive waterfront of New York as a place for resort. There is a reason for that. Pollution in New York City includes a sewer and drainage system which even a moderate storm overwhelms. Significant ozone and particulate matter pollutes the city’s air. The American Lung Association estimated that up to 3,000 lives per year in the greater metropolitan area are lost to particulate pollution. The city has taken steps to reduce the amount of pollution to which its residents and visitors are routinely exposed. The density of the population and the city’s industrial base ensure the problem remaining for the foreseeable future.

The Bay Area is one of several heavily polluted regions of California. Govtech.com

20. San Francisco, California

San Francisco Bay is heavily polluted. The waters of the bay test high for various heavy metals, including mercury. In recent years the city endured a spate of bad air days, many driven by the wildfires which have plagued California. Local waterways suffer from storm runoff from the city, which drains its garbage strewn rainwater into them. Fertilizers from gardens and lawns wash into the bay, encourage algae growth, and reduce oxygen. Heavy metals poison birds and fish, and make the waters unsafe for human use. The bay is the center of the region’s ecosystem, and its health affects the health of all life in the area, including humans.

Albuquerque’s air and water are among the most polluted in the United States. Albuquerque Journal

19. Albuquerque, New Mexico

Both ozone and particulate pollution levels rose in Albuquerque in 2019, continuing a trend which coincides with rising temperatures. Nonetheless the city’s air quality scored just over 60 (out of a possible 100), just above the national average of 58. Water did not feign so well. Water quality, which measures the quality of the water in the overall watershed serving an area, was 47. The national average was 55. Heavy industry and railyards add to a problem with both air and noise pollution in some areas of Albuquerque. Gasoline and diesel fuel storage sites, and the trucks which service them, release particulate pollution into the atmosphere. In 2019, the EPA awarded Albuquerque over $750,000 to help the city meet minimum clean air standards. It has not yet done so.

Air quality in Chico, already poor, became hazardous during the 2018 wildfires. sfgate.com

18. Chico, California

During the 2018 wildfires in California, the air quality index in Chico, California hit 365, well above the hazardous range. Nonetheless it was lower than in nearby Gridley, where it reached 366. Rains washed the air, carrying the soot and ash to the ground, where it washed into the water supply. Cleaning the air dirtied the water to the point that residents were advised to boil water before drinking. Much of the water supply remains contaminated with unacceptable levels of particulates, two years later. Ordinarily Chico scores quite well on tests for all forms of pollution. The events during the summer of 2018 indicated how quickly such scores can change.

It’s no surpise that heavily industrial and automobile dependent Detroit is one of the worst pollution sites in America. WDET

17. Detroit, Michigan

The Detroit metropolitan area contains a community known by its zip code, 48217. The zip code is the most polluted in the state of Michigan, and one of the worst in the United States. Sulfur dioxide is at dangerous levels, and ozone pollution exceeds the levels permitted under the Clean Air Act. The air breathed by residents includes benzene, chromium, and hydrogen cyanide. Cancer, asthma, heart disease, and birth defects are just some of the health effects felt by residents of the area at higher than statistically normal rates. According to a study by the University of Michigan, air pollution kills more than twice the number of Detroit residents than gun violence.

Industrial agriculture caused much of Modesto’s air and water pollution. CBS News

16. Modesto, California

Modesto sits in the Central Valley of California, one of the most productive agricultural areas in the world. Industrial agriculture dominates the region, along with a heavy reliance on cars and trucks. The result is high ozone concentrations, which have worsened with warmer and dryer weather. According to the Center for Disease Control, about one in thirteen Americans suffer from asthmanationwide. In Modesto about 10% of the population has the disease, an increase attributed to high ozone days. Particulate pollution is also high in Modesto, which received failing grades for air quality in 2018. Since then air quality has worsened, as warmer temperatures increased the number of bad air days.

St. Louis and other Mississippi River cities suffered more unhealthy air days from 2016 on. Missouri Department of Natural Resources

15. St. Louis, Missouri

St. Louis has a reputation for its less than salubrious climate, with hot, humid summers trapping the air over the city. Alongside the two major interstates which cross the city are several neighborhoods with significantly higher rates of several forms of cancer. Ozone and particulate pollution, mostly from vehicles travelling the interstates, contribute to the anomaly. Diesel fueled vehicles produce much of the particulates, while emissions from gasoline-powered cars contribute to the ozone. Periods of poor air quality often last for several days, even weeks, during the summer months. In April, 2019, St. Louis received an F grade for air quality from the American Lung Association.

Stockton faces unhealthy air quality and a growing water crisis which may rival that of Flint, Michigan. Recordnet.com

14. Stockton, California

Stockton is a major shipping center for the agricultural products grown all around the city. Shipping means trucks, which burn diesel fuel and leave particulates suspended in the air. Stockton also faces a crisis over its water supply, with unacceptable and increasing levels of lead in the water provided to its citizens. In 2016, famed activist Erin Brockovitch told city officials they were on the “fast track” to creating a water contamination disaster like that of Flint, Michigan. In 2013, Stockton included three of the most polluted areas in California, a state with many polluted areas.

Texas treats violations of the Clean Air Act with minimum fines, leading to several heavily polluted cities. Texas Observer

13. El Paso, Texas

The Environment Texas Research and Policy Center is a non-profit dedicated to improving the environment in the Lone Star state. In 2019 they revealed several El Paso companies releasing pollutants into the air at the rate of more than 23,000 pounds in 2017. They included the Western Refining in El Paso, Newman Power Station, and Capitan Compressor Station. Illegal release of pollutants into the air is not limited to El Paso. Across the state, Texas companies released more than 63 million pounds of pollutants in 2017. The fines levied by the state were less than 1% of the maximum, and came to about 2 cents per pound of pollutants, far less than the cost of compliance with state and federal regulations. The illegal emissions included carcinogens such as benzene and other harmful particulates.

Philadelphia’s reliance on coal for its power plants and industries makes its air among the worst in the country. Philly Magazine

12. Philadelphia, Pennsylvania

Philadelphia and its environs received a grade of F from the American Lung Association over the quality of its air in 2019. The City of Brotherly Love has heavily polluted air from both ozone and particulates, the latter from the extensive use of coal in power stations. Diesel fuel from railyards, trucks, and as a power source in industries adds to the particulate pollution. Cars are the chief source of the ozone pollution. As with other congested American cities, cars idling in traffic jams pump more emissions into the air. Warmer temperatures convert it to toxic ozone pollution. Recent cuts to the EPA budget and regulations resulted in increased pollution in Philadelphia and across the United States.

Pittsburgh’s air quality is better than it was fifty years ago, but still among the nation’s worst. Pittsburgh Post-Gazette

11. Pittsburgh, Pennsylvania

During the 1950s and 1960s Pittsburgh frequently found itself smothered in smoke from its industrial base. Today the city appears much cleaner, since most of the heavy industries moved away, or created cleaner facilities. Ten facilities – known in Pittsburgh as the Toxic Ten – continued to produce heavy amounts of particulate pollution in the Steel City. The ten pump 83% of all particulates into Pittsburgh’s skies and water, while automobiles feed the ozone pollution daily. Since 2017 Pittsburgh’s air quality deteriorated annually, earning it all F grades from the American Lung Association in 2019. Recent studies demonstrate the air over Pittsburgh continues to get worse.

Another California city where the air frequently exceeds endangers health. ABC30

10. Madera, California

The American Lung Association combined the communities of Fresno and Madera in its 2017 rankings, giving them an F for Air Quality. Since then, relaxed federal regulations governing emissions contributed to the air quality worsening, rather than improving. The region ranked third in the nation for the highest concentration of ozone pollution. For particulate pollution it bested itself, ranking second among the worst American cities for air quality. The region saw improvements in the decade preceding 2015, when drought and wildfires contributed to the upturn in airborne pollution. Since then the air quality continued to worsen through 2019.

Chicago, Illinois, enshrouded in a blanket of unhealthy smog. WTTW

9. Chicago, Illinois

Chicago heavily relies on coal for its industrial base and power plants. Despite the myth of clean burning coal, it is a major contributor to particulate pollution. Clean coal does not burn cleanly, instead the emissions are captured and returned to the ground. The technology is expensive and difficult for older coal burning facilities to adopt. In Chicago, many have not. The American Lung Association moved Chicago up the list of the most polluted cities in the United States for three consecutive years. In 2019 it reached the position of the 18th most polluted American city, with coal and diesel fuel identified as the major culprits.

The air quality in Salt Lake City often threatens the health of its residents. Salt Lake Tribune

8. Salt Lake City, Utah

In December 2019, a temperature inversion over the region of Salt Lake City gave it the worst air quality in the United States. The inversion held the ozone and particulate pollution in place. Particulate pollution reached levels more than 9 times greater than in Los Angeles. Ozone pollution was similarly high. During winter months inversions are more common, breathing masks are seen worn by citizens on the streets. Television and newspapers reported doctors recommending the wearing of breathing masks with a rating of N95 or higher, especially by the elderly or those with breathing problems from asthma or COPD.

As in several cities nationwide, efforts to improve Denver’s air quality have stalled in recent years. Denver Westword

7. Denver, Colorado

Those seeking clean Rocky Mountain air won’t find it in the Mile High City. Colorado ranks highly on the list of states violating federal clean air regulations. Denver is one of the worst areas of the state. Heavy construction across the city contributes to the high particulate count in the air. In 2018, Denver’s air quality rated elevated levels of pollution for 282 days. Ozone levels in Denver routinely reach elevated levels, fed by the city’s reliance on automobiles. Tailpipe emissions remain in the already thinner air, and convert to ozone which hovers over the city.

San Diego’s heavy reliance on automobiles makes its air quality unhealthy in warm weather. San Diego Union-Tribune

6. San Diego, California

San Diego’s image as a city of pristine skies is largely false. The city ranked as the sixth worst in air pollution since 2015. In 2019 the American Lung Association counted San Diego as part of the Chula Vista-Carlsbad-San Diego triad. Automobiles serve as the main contributors to the ozone pollution which permeates the air in the region. For particulate pollution the city’s air improved over the same time period, and the ALA gave the region a grade of B. Nonetheless, the number of unhealthy air quality days in the region increased 42% since 2015, with the trend showing increases in each successive year.

Nuclear reactor site in Hanford, California. Wikipedia

5. Hanford, California

Hanford, an automobile dependent small city, ranks among much larger cities having the most polluted air in the United States. California’s recent droughts and wildfires only worsened the situation as far as particulate pollution. Hanford recently failed to meet federal standards for particulates. Ozone pollution is also high, exacerbated by higher temperature trends over the past decade. According to city officials and consultants, climate change makes reducing emissions mandatory, especially tailpipe emissions from cars. The technology to reduce emissions is essential because cleaning the pollutants already present in the air is threatened by climate change.

California’s industry, agriculture, topography, and automobiles, all contribute to the number of heavily polluted cities in the state. Fresno Bee

4. Fresno, California

Fresno is the 34th most populous city in the United States, but ranks among the highest for pollution. In Fresno the air is heavily polluted, as is the ground and the watershed. Industrial farming added pesticides and herbicides to the ground and waterways. Surrounded by mountains, Fresno acts as a collecting site for the contaminants released into the air by the industries and farms of the Central Valley. About 1 in 6 children in the region have asthma, as of 2019. The rate is the highest in the state of California. Radon samples in Fresno reached a count of 2600. The national average is 700.

Unhealthy air and an aging demographic in Phoenix combine to create a potential health crisis. whowhatwhy.org

3. Phoenix, Arizona

Phoenix is an example of the contribution to air pollution attributed to urban sprawl. The city is dependent upon the automobile to connect with its suburbs and neighborhoods. Heavy reliance on cars increases tailpipe emissions, and rising annual temperatures creates more ozone. Phoenix ranks among the worst American cities for ozone pollution. Tailpipe gases exposed to sunlight create ozone through a chemical reaction. Phoenix receives a high amount of sunlight year-round, creating ozone levels which gave it an F for air quality in 2019. The city continues to suffer from urban sprawl, increasing its dependence on the automobile.

Bakersfield, one of the worst places to breathe in the United States, year-round. Scripps

2. Bakersfield, California

Like Fresno and Madera, the mountains which surround Bakersfield help trap the pollutants released into the air over the city. Bakersfield’s air pollution makes it one of the worst communities in the United States for air quality. Efforts to improve the air quality made some progress in the early 21st century, but recent wildfires and rising temperatures hindered attempts to clean the air. The number of days with unhealthy ozone levels went up every year since 2015. The state’s attempts to eliminate the use of fossil fuels is one step in improving air quality, though it’s met with heavy resistance.

Over 1,300 deaths annually in Los Angeles are attributed to its unhealthy air quality. ABC7

1. Los Angeles, California

Los Angeles and its surrounding communities have the worst air quality in the United States. The blanket of smog over the city, replenished daily by hundreds of thousands of sources, spreads over other California communities. The sources include the shipping industry, trucking companies, and commuters in their automobiles. Heavy industries add pollutants to the air. Los Angeles averages over 150 days per year of unhealthy air. The pollution creates memorable sunsets, but those watching them sear their lungs with pollutants. The pollution dome over Los Angeles is seen from space by satellites and astronauts. Though some improvements have been achieved over the last decade in particulate pollution, the city remains the worst in ozone pollution in the United States.