Los Angeles has a history of smog. The problem is exacerbated by its natural geography — the sprawling city is shaped like a bowl, which traps fumes blown by Southern California's sea breeze, and causes them to linger over the city, according to Smithsonian Magazine and the Los Angeles Times.

During the 1940s people began to notice the smog, but many thought it was clouds. They weren't.

"It was just the poor quality of the air that was a hazy, acrid, smelly, burning presence," the Los Angeles Times wrote.

In July 1943, a particularly bad bout of smog caused red eyes and running noses. People thought the city was under a chemical attack from the Japanese.

The term "smog" eventually entered the popular vernacular, mixing the words smoke and fog.

At times, the air pollution would be so concentrated in certain areas that it looked as if the city disappeared entirely.

Here, women in 1949 dabbed their eyes and noses.

On bad days, cars would appear from out of the smog. Visibility was so bad that people had car accidents, per LAist.

Accidents like this one in 1948 were common occurrences in the highly polluted Los Angeles roads.

In 1949, smoke from a trash dump covered the city. Later, fearing the effects of smog on the city's inhabitants, Gov. Goodwin Knight restricted the open burning of garbage. It was made illegal in 1958, per the Los Angeles Times.

The city had more than one million cars by 1940, according to the Smithsonian Magazine.

But it wasn't until the early 1950s that car exhaust was established as one of the primary causes of smog, Wired reported.

Cars contribute to ozone, which was the main cause of the smog. The ozone layer up in the atmosphere protects life on Earth from harmful UV rays. But when it's near the ground, ozone is a harmful gas that can trigger health issues like asthma.

Smog continued to blanket the city in the 1950s. This is the view from the Los Angeles City Hall in 1954, after eight days of heavy smog.

Lee Begovich, who moved to the city in 1953, told the Washington Post she was stunned when wind blew the smog away one day and she finally, for the first time, saw the San Gabriel Mountains to the northeast.

Peering at the city, the Washington Post wrote, was "like peering into the smoke-filled backrooms of the era's bars."

In 1954, Getty wrote that there were so many red eyes, one person said "you couldn't tell the people with hangovers from those who went to bed the night before."

People wore masks to counter what the Washington Post described as "eye-burning, lung-stinging, headache-inducing smog."

At least one woman wore a plastic helmet while relaxing at Santa Monica beach. At the time there were also bush fires, so while the helmet protected her from ash, it didn't stop smog from seeping in.

In 1958, the city even set up a smog relief team to provide residents with "fresh air" brought from outside of Los Angeles. Whether it was effective is unclear.

Continuing into the 1960s, parts of Los Angeles were getting 200 smoggy days each year.

Smog continued to cover the city as Los Angeles expanded, which meant more factories and highways. The city did have Air Pollution Control, an early pollution monitoring group.

Here's Grand Avenue in 1967, after efforts to limit pollution began being implemented by the city.

When the Clean Air Act was passed in 1970, Congress approved an amendment that allowed California to incorporate harsher pollution controls than the rest of the country, the Washington Post reported.

Air pollution officers actively monitored the highways for emissions.

The start of regulation didn't mean the pollution just went away immediately. This is hazy Los Angeles in 1972.

Here, that same year, smog was trapped against the mountains.

Smog still covered the San Gabriel Mountains at times in 1972.

In 1973, Los Angeles skyscrapers were blanketed in smog.

At least the shape of the buildings could be made out.

Over the years, the air quality in Los Angeles had improved thanks to the Clean Air Act, which helped lower emissions from cars and industry, the Washington Post reported.

The city's air quality future is still far from clear. Per IQAir, Los Angeles is the US city with the second-worst air quality (behind only Minneapolis) and the 72nd worst city for air quality in the world.

In fact, multiple cities in California continue to rank among the worst for air quality.

The 2018 National Climate Assessment warned that "climate change will worsen existing air pollution levels," according to the Fourth National Climate Assessment and NASA.

While LA doesn't look as bad as it did before the Clean Air Act, it still gets smoggy days.

This story was originally published in January 2020 and was updated in May 2025.

By the 1970s, the San Francisco Bay was badly polluted, with sewage and wastewater from industrial facilities dumping in the bay from over 83 points of entry, the San Francisco Baykeeper reported.

Pollutants in the sewage dumped in the Bay peaked in the late 1960s, according to the California State Water Resources Control Board.

In 2019, the EPA ruled the land, owned by Cargill Salt, was not bound by the Clean Water Act, Mercury News reported.

Today, battles remain over who can be held responsible for the water quality off the coast of San Francisco — a Supreme Court ruling this month could impact the EPA's power to enforce water quality regulations.

The court sided with the city of San Francisco in a 5-4 decision, arguing the agency didn't have the power to enforce broad regulations on the quality of a body of water. While the agency can instruct permitholders to follow certain requirements in a bid to avoid pollution, it shouldn't hold them responsible for the ultimate quality of the water, which is out of their control, the court said.

During the 1970s, the biggest problem for the city was ozone pollution, which mainly comes from cars, industrial plants, power plants, and refineries.

The photo was taken in 1972, according to the National Archives.

The EPA regulates waste now, and sets criteria for landfills. While the open dumping of waste is banned, it still happens.

Here, a screen has been placed across the water to trap trash. A heavy rain could break it, but it was effective when cleaned often.

Truckers in the 1960s called Birmingham "smoke city," Bham Now reported.

North Birmingham was the most polluted area of the city.

Because Cleveland was an industrial city, the pollution was severe.

In this photo from 1973, an empty lot on Superior Avenue, Cleveland, was filled with trash.

In 2016, a report released by New York University said 41 people living in Delaware still die because of air pollution every year, The News Journal reported.

The sewage came from the Metro Sewage Treatment Plant, per the EPA.

In the late 1980s, the air pollution got so bad, the city developed a visibility standard — it asked whether downtown workers could see mountains that were only 35 miles away, The New York Times reported.

While the river has been much cleaner since the Clean Water Act was passed, trash and industrial contaminants still end up in it, The Kansas City Star reported. In 2023, NPR reported that volunteers with Missouri River Relief have picked up more than 2 million pounds of trash from the river since the organization began in 2001.

In 1943, 30 years before this photo was taken, the smog was so bad, the city's residents thought there was a gas attack, according to the California Sun.

In this photo from 1972, the air-pollution control department checks for violators.

Fumes billow from Kaiser Aluminum Plant's smoke stack in 1973.

In the 1970s, the EPA found 66 pollutants in the city's drinking water. And the city's water is known for its oily taste, per The Washington Post.

The sewage was photographed darkening the water in Bayonne, New Jersey, in 1974.

Here, a pile of illegally dumped trash ruins the view of Manhattan and the Twin Towers in 1973.

The abandoned Beetle was photographed in 1973.

The EPA now helps regulate how the city disposes of trash to prevent dumping in the Atlantic.

In 1965, a study by New York City Council found breathing New York's air had the same effect as smoking two packets of cigarettes a day, The New York Times reported.

Between April and June of that year, 487,000 gallons of oil were dispersed in the New York Harbor and its tributaries, The New York Times reported.

The New York Bight is a triangular area that reaches from Cape May in New Jersey to the eastern tip of Long Island. The city allowed a ConEd plant to burn coal in the 1970s amid a fuel shortage, The New York Times reported. But coal has caused air and water pollution and destroyed wetlands, according to the National Archives.

In the 1970s, New York produced 26,000 tons of solid waste every day, according to the National Archives.

There were different distances for dumping different substances.

The sludge would settle on the bottom of the ocean, "like mud, killing plant life and creating what has been described as a "'dead sea,'" The New York Times reported.

In 1974, more than 3 million tons were dumped in the bight, according to the National Archives.

A photo shows trash strewn across New York City streets in 1973.

If you look closely you can see scavenger birds flying over the trash.

In 2018, a study found the city was becoming more polluted between 2014 and 2016, after several years of decreasing pollution, Philadelphia magazine reported.

The city was once dubbed "Hell with the lid off," per The Allegheny Front.

According to Mayor Tom Murphy in 2001, the biggest complaint he heard about the city was that it was too dirty, the Pittsburgh Post-Gazette reported.

NPR reported that the river is much cleaner today, 50 years since the Clean Water Act.

The pollution was blamed on a "hundred years of under-estimates, bad decisions, and outright mistakes," a director of the Federal Water Quality Administration told The New York Times.

His description can be applied to a lot of the US before the EPA.

This story was originally published in August 2019 and was most recently updated in March 2025.