As wildfire smoke chokes LA, see how many-bad air days your county had

Thousands of people are fleeing their homes as wildfires rage in California. Strong winds fan the fast-moving fires and smoke pollutes the air.

In Los Angeles, air quality was between good and moderate in the early parts of the day on Tuesday. By sunrise on Wednesday, however, air quality reached hazardous levels that threatened people’s health.

This is happening more and more often, a USA TODAY analysis of U.S. EPA data shows.

Closer look: How wildfire smoke can harm you.

Air pollution has dropped significantly in the U.S. since the 1970s. However, wildfires have emerged as a growing threat – making it harder to clean up the air and protect people’s health. As of 2017, wildfire smoke had surpassed fuel combustion from electricity generation and industry as the leading source of dangerous small particles that make people sick.

In 2023, the last year for which full data is available, more than 140 million people lived in a place with at least a week of bad air quality, the analysis of federal data showed. That's the most in a decade.

That year, Canadian wildfires sent smoke sweeping across much of the U.S., engulfing the New York City skyline for days under an orange sky. And the fires have continued.

Verified data for 2024 is not yet available, so it's too early to say what happened last year, said Kevin Stewart, Director of Environmental Health at the American Lung Association. But earlier in 2024, multiple states issued air quality warnings as smoke from “out of control” wildfires in Canada blew across the border for the second year in a row.

The smoke makes people sick.

Afif El-Hasan, a pediatrician in Orange County, California, sees more patients with respiratory illnesses such as asthma during wildfire season. 

“It's going to give you more susceptibility to becoming ill, and it's going to predispose you to other problems as well,” he said.

El-Hasan has action plans for many of his patients to start or increase dosages of preventative asthma medications if they are exposed to wildfire smoke.

“Once they get an asthma flare, if they're in the middle of wildfire smoke, they can become sicker faster.”

Read more: 'Hurricane of fire' has LA area ablaze, and 'worst is yet to come': Live updates

Who does it affect the most?

Wildfire smoke contains tiny particles, which are much smaller than the width of a human hair and penetrate deep into the lungs, enter the bloodstream and pose health risks, even to otherwise healthy people.

Prolonged exposure to this fine particulate matter (known as PM2.5), has been linked to serious health conditions, including lung cancer, heart attacks and low birth weight.

Every year, air pollution contributes to millions of asthma emergency room visits around the world and hundreds of thousands of premature deaths in the US.

Low-income families are particularly vulnerable to the health impacts of air pollution, as they are more likely to live in areas with high levels of polluted air. Research has shown that people of color are exposed to higher levels of air pollution than the national average.

“I still see a huge problem where underserved communities can sometimes have some of the worst air quality and some of the least resources to combat the effects of that air quality,” El-Hasan said.

The USA TODAY analysis focused on days were the Air Quality Index, or AQI, was above 100.

At this point, breathing the air primarily poses a risk to sensitive groups but can also impact healthy people, albeit to a lesser extent, Stewart said.

“If you don't do a lung function test, you won't know that the numbers are off. You just might say, ‘I just don't feel up to it today,’” Stewart said.

Vulnerable groups include those with asthma, lung or heart disease, older adults, children and those with higher exposure, such as outdoor workers, experts say.

Cleaning up air has gotten harder

The USA TODAY analysis revealed that Los Angeles and four other California counties, home to about 15 million people, had the most days in 2023 with air quality deemed unhealthy for sensitive groups or worse.

However, the number of bad air quality days in these five counties has been steadily declining. For instance, Kern County cut its unhealthy air days from 207 days in 2004 to just 70 in 2023. The figure nearly halved in Los Angeles County over the same period.

State officials attribute this improvement to the state’s regulatory push towards zero emissions, including expanded EV charging infrastructure, limits on vehicle idling, replacing old trains, and reducing landfill emissions.

According to the Environmental Protection Agency, emissions from six major pollutants in the country have plunged about 80% since 1970, when the Clean Air Act empowered the agency to regulate emissions of hazardous air pollutants.

But as emissions from sources like electricity generation have trended down, wildfire emissions have ramped up.

A second USA TODAY analysis showed that wildfires have been the leading source of the tiny particles called PM2.5 since 2017. Researchers have already found that the rate of improvement in fine particle pollution levels has slowed down and even reversed in some cases.

As temperatures rise due to human-caused climate change, scientists predict wildfires will become more frequent and intense, particularly in western states.

“The bottom line is, we are reducing air pollution,” Saravanan Arunachalam, a professor at the University of North Carolina at Chapel Hill, told USA TODAY. “But natural sources such as wildfires, which are somewhat attributable to climate change, may also play a role.”

“It just all happened so quickly”

After her daughter Lucille was born early in August 2020, Anna Braje stayed at the hospital for a few days. In early September, they were finally enjoying time at their house in Southern Oregon when Braje realized something was wrong.

“It was such a clear blue day before, and it just all happened so quickly,” Braje said.

Strong winds were blowing, fueling a nearby fire. Braje grabbed her daughter and two journals her dad gave her for her high school graduation and drove away in their Subaru.

“I swerved off the road and around the power pole of where the emergency vehicles were parked, and when I rounded that bend in the park, there was no going back – the first manufactured home was already caught on fire,” Braje said.

Across the state, September 2020 fires brought ?record breaking conditions as air quality monitors maxed out.

Further north in Portland, which saw its first ever “hazardous” days from wildfire smoke, Alexa Van Eaton took a photo of the ash that had been falling.

“One of the things that struck me about the wildfire ash fall back in 2020 was that it was remarkably similar to what it feels like to have volcanic ash fall in a region,” said Van Eaton, who’s a volcanologist at the US Geological Survey.

That year, the Pacific Northwest reported the most acres burned since reliable recordkeeping began, and that record was shattered once again in 2024, the Statesman Journal reported.

The Rev. Chuck Currie, a minister in the United Church of Christ in Portland, says summers in the city are one of the best things on earth. But now the climate is changing.

“What we noticed is that from August to September, you're going to run into smoke in the Portland area and across the Northwest. It didn't used to be that way,” Currie said.

Last September, Currie went on a camping trip with his wife to Mount Hood.

“The whole time we were there, you couldn't see the mountain because the smoke was so thick.” Currie said. “After a couple days, we just got up and went back home because it's pretty miserable.”

Rollback fears loom in Trump’s second term

Experts say that if clean air protections disappear at the same time as wildfires increase pollution, Americans could see hard-won improvements in air quality go up in a puff of smoke.

That’s especially true when climate change is adding to the challenge of protecting public health.

Concerns have grown in anticipation of potential rollbacks during President-elect Donald Trump’s second administration. Air pollution experts note that blueprints from conservative groups with connections to Trump, such as Project 2025 and America First Agenda, have policy proposals that will weaken the environmental agency’s authority to enforce strict air quality standards.

“If the new administration has plans to perhaps reverse some of those regulations, then what you've done is put the country backwards,” said Arunachalam, the University of North Carolina professor.

Experts noted the backsliding of dozens of environmental rules during Trump’s first term. Many were related to air pollution and emissions, including the rollback of Obama-era fuel efficiency requirements, which mandated automakers to improve the fuel economy of new cars and trucks by 2025.

John Walke, a senior advocate at the Natural Resources Defense Council, doesn’t expect the second Trump term to be any different from his first.

“I wish it were otherwise, but having been through the first four years, I feel very confident in predicting that,” said Walke, a former attorney in the EPA’s Office of General Counsel.

During his first term, Trump “advanced conservation and environmental stewardship while promoting economic growth,” Karoline Leavitt, the Trump-Vance transition spokeswoman, told USA TODAY in an email statement.

“In his second term, President Trump will once again deliver clean air and water for American families while Making America Wealthy Again.”

Walke said there were almost no rules or regulations adopted to improve air in Trump’s first four years, adding: “All of the major and even minor rules undertaken during the Trump administration were focused on rolling back Clean Air Act protections.”

Some of those rollbacks persist to this day, Walke said.

Laura Kate Bender, an assistant vice president at the American Lung Association, said that the non-partisan organization is ready to defend clean air progress during any administration.

“It's no secret that President Trump has pledged to hold back environmental protections,” Bender said.

“We're going to use all the tools in our toolbox to defend them.”

Suhail Bhat contributed to this report.

Ignacio Calderon is a data reporter for USA TODAY. Reach out to him at icalderon@usatoday.com

This article originally appeared on USA TODAY: Polluted air affects 140 million Americans. Are you among them?