The Brief

Gross black dust on your windowsill. Sickly yellow haze that obscures the mountains. Childhood memories of recess cancelled due to smog alerts.

You know the air here is dirty. Now learn why.

Once Upon A Time

The L.A. smog story goes a little like this: on July 8, 1943, a mysterious haze descended on the city.

"People were having car accidents," Chip Jacobs, co-author of Smogtown: The Lung-Burning History of Pollution in Los Angeles, told LAist. "Mothers were wondering why their kids' eyes were watering. Police officers were spinning loopy."

What was this strange haze? Was it a gas attack? Smoke from factories? From some distant fire?

To solve the mystery, local officials formed the nation's first air quality regulator, the Los Angeles County Air Pollution Control District. They began looking into the problem and quickly learned that there were a lot of sources of air pollution in greater L.A.: people burning trash in their backyards, oil refineries, smudge pots (which are small, smoky fires used by citrus growers to keep trees warm at night), and factories.

But soon, a Caltech scientist figured out that cars and gasoline were largely to blame for the eye-watering, lung-searing haze.

A smog-shrouded view of downtown Los Angeles on October 7, 1968.

(

Los Angeles Public Library archive

)

What Do Cars Have To Do With It?

Car exhaust has two main components: hydrocarbons, from the gasoline, and nitrogen oxides, which are formed inside hot, internal combustion engines. Both are harmful in and of themselves, but when they float into the sunny, Southern California air, the sunlight bakes them into a new chemical: ozone, also known as smog.

Once scientists figured out what caused smog, the crackdown began: in 1967, a new state air quality agency, the Air Resources Board, was formed. It enacted tailpipe emissions standards for cars. It required catalytic converters on new models, cleaner gasoline and, at the gas pump, those little rubber boots that trap fumes from the nozzle. In 1984, smog checks began statewide. Other industries had to clean up, too: oil refineries, cement plants, power plants. And as California cleaned up its air, other states and the federal government followed.

L.A. has the worst ozone, or smog, in the country, according to the American Lung Association's 2021 State of the Air Report.

(

American Lung Association

)

Bad Now Vs. Bad Then

The air is a lot cleaner now. In 2020 , we had 157 days of unhealthy air, compared to well over 200 in the late 1980s. However, 2020 tracked the highest number of unhealthy air days since 1997, even with pandemic restrictions seeing a drop in auto travel. So when it's smoggy, it's not as smoggy as it used to be.

But Los Angeles still has the worst smog in the country, according to the American Lung Association's 2021 State of the Air report. (Again, scientists call smog "ozone." But they're the same thing).

Greater L.A. exceeded federal air quality standards for 157 days in 2020.

(

South Coast Air Quality Management District

)

Part of the problem is that it's been hot, incredibly hot. And heat speeds up the process of ozone-formation. Experts are trying to figure out whether the spate of bad air is a new trend, reversing years of steady progress.

"Is this weather, or has this become climate?" said Atwood. "We're grappling with that question basically."

What Makes Our Smog So Special?

Three reasons.

• One, there are a lot of us, and we own a lot of cars. Angelenos own 0.54 vehicles per person, compared to 0.43 in New York City. Also, we have the busiest ports in the country, which means tens of thousands of heavy-duty diesel trucks are on our roads, and they are way dirtier than cars.
• Two, the mountains that ring the L.A. Basin trap that pollution as it gets pushed eastwards by sea breezes.
• And three, our climate. Nearly three out of four days in L.A. are sunny. And the L.A. Basin frequently experiences a weather pattern where a layer of warm air will sit on top of a layer of cooler air and prevent it from dispersing. That traps pollution closer to the ground. Think of it like putting a lid on a pot.

Where's The Dirtiest Air? Where's The Cleanest?

Because the wind blows smog east, towards the mountains, the air is worst there. So places like Redlands, San Bernardino and even the tiny, mountain community of Crestline have far worse air quality than coastal cities like Long Beach or Santa Monica.

But there's another factor to consider besides smog: the raw vehicle emissions that combine to make smog can also have localized health impacts. So if you live within 500 feet of a busy road or a freeway, you're in a pollution hot spot, because that's where vehicle emissions are the most concentrated. (Use this handy map made by our friends at the LA Times to figure out how close you live to a freeway.)

Trucks on the SR 60 Freeway drive by Anna Gallegos' backyard in Mira Loma Village, California.

(

Andrew Cullen for LAist

)

In the very worst places to live, like near a freeway in San Bernardino, you will be exposed to both smog and raw vehicle emissions, said Ed Avol, the head of the Environmental Health Division at the USC Keck School of Medicine.

"It's sort of like a double whammy, so you get both the local impact of being near a roadway, and you also get the accrued accumulation of pollution that's become a regional issue," he said in an interview with KPCC/LAist in April.

What Will Breathing Dirty Air Do To Me?

When you breathe in dirty air, it triggers an inflammatory response in your body. And once that happens, a lot of bad things can happen. In the short term, air pollution can cause:

• Difficulty breathing and chest pain.
• Increased rates of asthma.
• Respiratory diseases like bronchitis and pneumonia.
• Lost school or work days.
• Doctor and hospital visits.
  

Over the long term, it's much worse. Kids who grow up breathing dirty air, whether it's from living near a freeway or in a smoggy area, or both, have weaker lungs that don't work as well.

"If they never get that maximum lung growth early in life, it looks like it's permanently lost," Avol said.

For older adults, air pollution can contribute to cognitive decline, memory loss and premature death. It can also exacerbate heart disease, diabetes, obesity and cause cancer. There's even research suggesting fetuses are harmed when their moms breathe dirty air.

"In a cynical, joking way, you could say we believe air pollution causes everything," Avol said.

Smog-making cars on March 22, 2006 in L.A.

(

David McNew/Getty Images

)

How Can I Protect Myself And My Family From Bad Air?

One of the most common ways people are exposed to pollution is while driving. So when you're on the freeway, be sure to keep your windows rolled up and re-circulate the air, instead of drawing it in from the outside. Changing your air filter also helps. And new cars are more tightly sealed than older cars, keeping pollution out.

If you can, try to live at least 500 away from a freeway or busy road. If you can't, using HEPA air filters has been shown to significantly reduce indoor air pollution when the air outside is dirty. Clean that black dust, which is a combination of diesel soot and rubber dust from tire wear, off your window sills.

Outside of the home, try to walk or bike on less busy streets, to limit your exposure to vehicle exhaust. When waiting for the bus, stand back from the street corner, where pollution levels soar when vehicles accelerate from a stop. And don't exercise near busy roads during rush hour, especially in the morning, or when the air is especially bad.

You can also check the air quality every day. This South Coast Air Quality Management District map will give you a good overview of air in your area. You can also check the Purple Air network, which measures particulate matter (like soot, dust and wildfire smoke), or have a low-cost air monitor installed at your home or work.

What Do We Need To Do To Make The Air Actually Clean?

It all comes down to transportation. Cars and trucks make up nearly 90 percent of the smog-forming pollution in Southern California (not to mention they are also the largest emitters of greenhouse gases in the state), and it's because they run on gasoline and diesel.

Switching to fuels with zero tailpipe emissions, like electricity and hydrogen fuel-cells, will make a huge difference, says Will Barrett, the clean air advocacy director for the American Lung Association.

Trucks drive along Interstate 80 on February 18, 2014 in Berkeley, California.

(

Justin Sullivan/Getty Images

)

"We need to see more focus and urgency on the conversion of the heavy duty sector to zero emission technology," he said.

But heavy duty trucks have proven tricky, so far, to electrify, because they would require a massive battery to power them over long distances while carrying heavy loads. Also, truckers would need frequent, convenient charging stations, and that infrastructure doesn't exist yet.

California regulators, ever the clean-air optimists, are throwing cash at the program. The ports of L.A. and Long Beach, for example, have a goal of shifting their entire fleet of largely diesel trucks and equipment to zero emissions technology by 2035 -- at a cost of $14 billion. If they can figure it out, all of our lungs will benefit.

This story is part of Elemental: Covering Sustainability, a multimedia collaboration between Cronkite News, Arizona PBS, KJZZ, KPCC, Rocky Mountain PBS and PBS SoCal.

Nithya Raman turned the tide in the L.A. mayoral race by winning over large swathes of the city that voted for Karen Bass in 2022, according to an LAist analysis of election data.

Bass was a favorite in many areas that voted for Rick Caruso when she faced him in 2022. She held onto a majority of voters across South L.A., but lost much of her previous support.

The switchup came after Bass — a veteran in progressive politics — took a relatively-conservative approach on issues like policing and high-density housing developments compared to Raman, a member of the Democratic Socialists of America.

The Los Angeles Homeless Services Authority told its employees Friday to stop work, shut down their computers and stay off agency systems while it looked into “a potential security issue affecting our systems,” its chief executive confirmed to LAist.

That shutdown order was still in place Monday evening, according to a LAHSA official not authorized to speak on the record.

Gita O'Neill, the agency’s interim CEO, told LAist on Friday evening that the agency did not “yet have enough information to say definitively whether any sensitive or confidential personal information was accessed.”

She has not answered questions about whether or not services for unhoused people are disrupted.

Gita O’Neill, interim CEO of LAHSA, speaks ahead of the annual homeless count on Jan. 20, 2026.

(

Jordan Rynning

/

LAist

)

LAHSA holds highly sensitive information collected from people experiencing homelessness in the region. The agency oversees the Homeless Management Information System, or HMIS, which includes unhoused people’s names, dates of birth, Social Security numbers and disabilities, as well as self-reported mental health and substance abuse history, income sources and domestic violence history.

In a statement Monday, LAHSA said it had taken its internal computer systems offline “as a precaution” and “engaged outside cybersecurity specialists to investigate the nature and scope of the incident.” The statement, sent on O'Neill's behalf by outside public relations strategist Trevor Daley, continued to call it “a potential cybersecurity incident.”

The agency is “taking steps to maintain essential operations,” the statement added, saying LAHSA “remains open” while the investigation continues. It said the agency is working with its technical and legal teams.

What staff were told

Friday’s email to "Team LAHSA" carried the subject line "URGENT: Log Off and Shut Down for the Week." LAist obtained a copy, and O'Neill confirmed by text message that she had sent it.

“As a precaution while we look into a potential security issue affecting our systems, we're asking all staff to stop work and take their machines offline for the remainder of today and through the weekend,” the email said.

It told employees to “Log off and shut down your LAHSA computer” and not to log back in or connect to LAHSA systems, including email, “until you receive an all-clear from us.”

The email also told staff to report anything “unusual” before shutting down, such as “files renaming on their own, unexpected pop-ups or messages.”

What LAHSA leadership has said

In a texted response to LAist on Friday evening, O'Neill said she asked staff to take their computers offline “out of an abundance of caution” while the agency’s IT team assessed the situation.

“Our IT team is actively reviewing the situation now and working to understand exactly what occurred and whether any information was affected,” she wrote. “Protecting people’s personal and confidential information is a top priority in that review.”

Leaders of three LAHSA-funded service providers told LAist on Monday afternoon that they had not received any communications from LAHSA about the potential cybersecurity issue. All three use the HMIS system that holds unhoused people’s personal details.

Previous attacks against another LA housing agency

Another L.A. housing agency was previously hit by cyberattacks. The Housing Authority of the City of Los Angeles — a separate agency known as HACLA — has said hackers got inside its network in 2022 and may have accessed people’s names, Social Security numbers, financial accounts numbers and medical information.

Two years later, HACLA was breached again, according to an official notice, with hackers potentially accessing names, dates of birth, Social Security numbers and phone numbers.

LAist reporter Aaron Schrank contributed reporting to this story.

Los Angeles County Supervisor Lindsey Horvath announced Monday that she is running to be the county’s first elected chief executive. Horvath is the only candidate so far to enter the race, which is set for 2028.

The new executive post will take the place of the county’s appointed CEO and implement key priorities of the county Board of Supervisors. The executive will oversee the county budget, which is currently roughly $50 billion, and labor relations with more than 100,000 employees.

Horvath was first elected to the Board of Supervisors in 2022 and was re-elected in June to another four-year term. She represents the county’s 3rd District, which covers the San Fernando Valley and parts of the Westside and Central Los Angeles. She is a former mayor of West Hollywood.

The supervisor made her announcement Monday via social media and her campaign website. She called the race a “once-in-a-generation opportunity.”

The backstory

Voters created the position in 2024 when they approved Measure G, which was proposed by Supervisors Horvath and Janice Hahn.

Among other changes, the measure allowed the Board of Supervisors to expand from five to nine members by 2030 and established an independent Ethics Commission, which held its first meeting last month.

The pushback

On Monday, Supervisor Kathryn Barger issued a statement saying she believed it was “premature” to campaign for the new county executive position when it remained unclear whether “the office itself is constitutional.”

Barger pointed to questions raised by former federal judge Stephen Larson about whether California’s Constitution allows an elected county executive to veto board decisions, control county contracts and take on powers state law currently gives the Board of Supervisors.

“Moving forward with an office that would fundamentally change how Los Angeles County is governed, without first resolving these questions, is putting the cart before the horse,” Barger said in her statement. “We need clarity.”

The primary election is scheduled for March 7, 2028.