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.

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Los Angeles Public Library archive

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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.

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American Lung Association

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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.

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South Coast Air Quality Management District

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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.

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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.

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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.

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"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.

A federal judge has now granted Paramount’s settlement agreement with 12 states that sued over the company’s takeover of Warner Bros. Discovery, allowing the companies to soon close their $81 billion mega merger.

In a Wednesday order, U.S. District Judge Araceli Martínez-Olguín ruled that the proposed consent decree was a “fair, reasonable, and good faith approach to address the competitive harms” alleged by the states’ lawsuit. Paramount previously called the antitrust challenge the last hurdle ahead of closing its Warner merger, and signaled that it aims to close its Warner acquisition as soon as early October.

Shortly after Martínez-Olguín’s ruling on Wednesday afternoon, the company announced that Ynon Kreiz — current chief executive at toy giant Mattel — will join Paramount on Oct. 5 and serve as co-CEO alongside David Ellison of the combined company.

A Paramount-Warner marriage will bring together two of Hollywood’s last five legacy studios. HBO Max, a library full of titles including “Harry Potter” and cable networks such as CNN will also find themselves under the same roof with CBS, the likes of the “Top Gun” franchise and the Paramount+ streaming service.

Top prosecutors from 12 states — led by California Attorney General Rob Bonta — sued in July with an initial goal of blocking the merger altogether. They alleged a Paramount-Warner combo would “extinguish competition” and lead to fewer choices for consumers, particularly movie theatergoers and cable customers.

Last week, the states agreed to settle these claims through new commitments from Paramount, including pledges to increase film production in the U.S. over the next five years, commit millions of dollars to a fund aimed at supporting workers displaced by the merger and establish new editorial monitoring of CNN and CBS.

When announcing the deal on Sept. 21, Bonta said the settlement was about “protecting people’s careers, the lives they’ve built here in California, the livelihoods their families rely on,” while maintaining it was not a vote of support for the merger.

Many critics of the tie-up, however, quickly decried the deal as capitulating to corporate pressure and said the proposed terms were too weak. Martínez-Olguín didn’t greenlight the terms right away — maintaining at a hearing on Thursday that the court isn’t merely a “rubber stamp” on a settlement of this kind and that she, like many others, still had questions.

The judge granted outside critics of the settlement — including members of the Block The Merger coalition and the League of United Latin American Citizens — a brief window to share their opposition with the court through amicus briefs. She also instructed Paramount and the settling states to respond to a letter from Democratic Sen. Cory Booker, who called for a more thorough review of the deal.

By Wednesday’s order, however, she concluded that the hopes for settlement terms to go further “do not rise to the level of legal violations upon which the Court can reject the parties’ negotiated resolution.”

The Block the Merger coalition on Wednesday maintained the settlement was a “toothless” deal.

“Allowing the Paramount Skydance-Warner Bros. Discovery merger to move forward with no meaningful structural remedies will cost jobs, mute creativity, weaken independent journalism, and damage our First Amendment rights,” Block the Merger said in a statement. But, the coalition added, “if there is one discernible benefit to the approval of this corporate takeover, it’s that people are now wide awake and paying attention –- and their anger is not going to fade away.”

The Writers Guild of America, which had filed its own suit shortly after the states in July, also reached a settlement agreement with Paramount last week — concluding that it couldn’t continue its legal fight alone.

This story first appeared on The LA Local.

Inglewood is staring down the barrel of a $30.8 million budget deficit next year, the city’s largest in at least two decades, but officials said locals don’t need to be worried. 

Inglewood’s budget ballooned after SoFi Stadium opened in 2020. City officials roughly doubled their spending from the general fund — the pot of money that pays for basic services from police to parks. 

Revenue also boomed in the first few years after the stadium’s opening, but since then hasn’t quite kept up with what’s been spent. 

City officials downplayed the projected deficit last week, saying in reports and presentations that reserves of more than $150 million will cover the gap this year and that they expect increased tax and other revenues to help take care of the problem in the future.  Mayor James Butts said locals have no reason to worry, and that the city’s reserves have enabled officials to be ambitious in their planning. 

Whether they have to dip into those savings at all depends on how locals vote for a ballot measure on Nov. 3. Officials predict Measure AT could wipe out the deficit entirely by bringing in as much as $45 million to $50 million extra in taxes on tickets to major events.

But_, if Inglewood continues to spend more than it takes in over the coming years and pulls too much out of its reserves, city officials could be pushed to lay off staff and cut funding for services, as they did during a fiscal crisis 15 years ago.

The City Council approved the budget proposal in a 4-0 vote at its Tuesday meeting. Councilmember Eloy Morales Jr. was absent.

Here’s a breakdown of Inglewood’s budget

Inglewood’s annual general fund revenue has grown by about $100 million over the last 10 years, driven in large part by increased property taxes and admissions tax.

But that growth has plateaued over the last five years, while expenditures continued to grow. The city plans to spend $279 million out of its general fund this year, more than double its annual spending prior to 2020.

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The city’s total budget is $675 million. It includes the general fund as well as special funds that pay for things like major construction projects and affordable housing.

Police take the largest bite out of Inglewood’s general fund, followed by the public works and parks departments.

Outside the general fund, the city has also budgeted $239 million for capital projects.

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Some of Inglewood’s largest sources of general fund revenue are property tax, sales tax and admissions tax. 

Property tax revenue has grown by leaps and bounds over the last five years, according to budget documents, but admissions tax and sales tax haven’t matched the growth.

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Officials hope city reserves and a ballot measure will fill the deficit

Inglewood has had budget issues before. The deficit approached $18 million in 2010, just before Mayor James Butts was elected, while reserves fell to around $11 million.

This time around, officials say Inglewood has over $150 million in reserves. 

Butts said those reserves have allowed the city to take an aggressive approach to improving streets, traffic lights and other city infrastructure.

“We put the money there because we want the city to be rehabilitated,” Butts said.

Pulling from reserves, though, isn’t something a city can do indefinitely. City Manager Louis Atwell wrote in a budget report that staff expect tax revenue to keep increasing and new developments to give the city an additional boost. With staff keeping an eye on operating costs, Atwell wrote, those revenues would narrow the city’s budget gap down the line. 

This year’s election could also come into play. The two city ballot measures voters will see — AT and BB — are the product of a larger battle between the city and its stadiums over billboard advertisements and the development deal that brought SoFi Stadium to Inglewood.

Either measure could have a substantial effect on the city’s books. 

Inglewood currently pulls in a 10% tax on SoFi Stadium tickets, but with an annual ceiling on how much the city can get. Measure AT, backed by billboard company WOW Media, would remove the cap and add a new 2.5% tax for the Intuit Dome.

Officials estimated it would bring in between $45 million and $50 million extra annually, more than enough to cover the city’s current deficit. Atwell cautioned, though, that the figures aren’t guaranteed and could depend on economic conditions, the timing of the measure’s roll-out and other factors. 

On the flip side, officials said Measure BB could curtail billboard fees and ratchet the deficit up to almost $39 million. 

The initiative would ban most commercial advertising on the large video billboards that have cropped up along the city’s main roads. Measure BB would cut off a revenue stream that, according to past budget documents, has brought the city between $3 million and $7.5 million. 

City officials itemized how much Inglewood made from billboards in each of the last 10 years, but did not do so in this year’s budget. 

The ballot measures are just a few items on a packed Inglewood ballot that includes elections for mayor, two city council members and three Board of Education trustees. 

International politics moved front and center in the Los Angeles mayor’s race Tuesday night, with the candidates offering differing views on how to describe what’s happening in Gaza.

Incumbent Mayor Karen Bass and challenger City Councilmember Nithya Raman answered questions separately at a forum sponsored by the Jewish Federation of Los Angeles at the Skirball Cultural Center in the Sepulveda Pass. The candidates were interviewed back-to-back on stage by moderator Alex Cohen.

The forum was designed to address the concerns of Jewish Angelenos.

Raman was asked about her use of the term “genocide” and whether it is appropriate to describe Israel’s attacks on Gaza.

L.A. City Councilmember Nithya Raman, right, on stage with moderator Alex Cohen at the Skirball Cultural Center during a mayoral forum on Tuesday, September 29, 2026.

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Jeff Rowe

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“I used it because other experts have used it to describe what’s happening,” she said. “And I used it because I felt compelled to speak out about issues that we saw, the images that we saw, the targeting of hospitals, the deaths of children.”

Bass had a different response from her opponent when asked whether she believes the term applies in Gaza.

“When I think of foreign affairs, especially conflicts, my focus is on how they impact the city of L.A. — no, I don’t,” Bass responded.

L.A. Mayor Karen Bass answers questions at a mayoral candidates forum held at the Skirball Cultural Center.

The Gaza Health Ministry estimates 74,000 Palestinians have died in the war, including many children and noncombatants.

The war started on October 7, 2023, when Hamas-led militants launched a surprise attack on Israel, killing around 1,200 people and kidnapping 251.

Genocide is an international crime defined by the United Nations as any act committed with the specific intent to destroy, in whole or in part, a national, ethnic, racial or religious group.

The U.S. government and Israel vehemently deny genocide is going on in Gaza. Many other countries and human rights organizations disagree, saying it is genocide.

Candidates differ on Israel boycott

The two also split on the boycott, divestment and sanctions movement against Israel.

Raman called it “a legitimate form of peaceful protest” against Israel over its treatment of the Palestinians, prompting loud boos from some in the crowd.

“I support people’s right to protest,” she said. “And I will fight for that right even when I don’t agree with protesters, or when I agree with protesters.”

Raman is a member of the Democratic Socialists of America, which supports the boycott and divestment of Israel.

Bass said she would oppose any effort to enact sanctions against Israel.

Cohen also asked Raman about her appearance with Hasan Piker, a left-wing Twitch streamer and outspoken critic of Israel.

Raman said she disagreed with some of Piker’s views, saying it’s important for elected officials “to go speak to them even when you disagree.”

Raman said she has been an outspoken critic of antisemitism and was the first L.A. elected official to denounce the 2023 attack on Israel.

National polls on Gaza

The divergence in views between Bass and Raman represents a larger shift in the Democratic Party over Israel.

A new AP-NORC poll found erosion of support for the longtime U.S. ally, with rising opposition from Democrats.

About one-third of U.S. adults — including roughly half of Democrats — believe that Israel has committed genocide against Palestinians during the war in Gaza, according to The Associated Press. About 2 in 10 Americans say Israel has not, and the rest, about half, don’t know enough to say.

A similar share, 30%, of Jewish adults say Israel has committed genocide, although about half, 49%, say it has not.

“40 hours, $2M+ AI credits, solve an open problem.”

So read the splashy announcement for the “Mathathon” at the California Institute of Technology in Pasadena. Dozens of teams would work to solve vexing math problems with the help of artificial intelligence as part of “the first hackathon ever devoted to research level mathematics,” according to the early September post. AI juggernauts Anthropic and OpenAI were set to sponsor the two-day competition.

The backlash came swiftly. Critics objected not only to using AI to tackle open problems, but also to the involvement of AI companies whose models and research practices they have criticized.

Within days, current and former Caltech mathematicians published an open letter calling on the undergraduate organizers to suspend the event. The Mathathon, they argued, would only fuel the creation of “slop mathematics” and serve as public relations for the companies.

Instead of canceling the event, Caltech student organizers responded as any mathematician would — they tried to solve the problem.

The undergraduates redesigned the competition. Instead of trying to solve open mathematical problems, teams will now aim to develop alternative proofs for existing, yet unsatisfying solutions. The November event will also no longer be sponsored by the companies that develop proprietary AI models.

“We came to the decision that we want to put up an event that unites the math community, rather than divides it,” Brian Zhao, one of the Mathathon organizers and a junior studying applied mathematics at Caltech, told EdSource.

The controversy over the Mathathon event laid bare the growing tensions unfolding in the mathematics community over what role AI should play in advancing the field.

AI has already helped to solve elusive math problems. OpenAI announced this month that it used an internal AI model “significantly more capable” than the latest publicly available models to solve one of the remaining six Millennium Prize Problems. But mathematicians have warned about AI’s negative impact on mathematics students, and criticized these companies’ approach to solving high-profile problems.

“To put it bluntly, AI companies are engaging in research misconduct,” wrote the authors of the open letter, which gained the signatures of 2,038 academics as of this week.

‘That’s not the culture of mathematics’

Earlier this summer, Zhao and his roommate came up with their idea of a fun weekend: lock themselves in a basement and try to solve math problems for 40 hours straight. He was inspired by hackathon-style competitions in which programmers and designers compete to build hardware or software under deadline.

The idea of using AI to try to solve open math problems was two-fold. With mathematics undergoing one of the biggest changes in decades because of AI, the Caltech undergrads wanted to organize an event to experiment with AI and better understand how the field may evolve by the time they start graduate school.

Also, the students hoped that advertising the event with flashy statements — like suggesting teams would have access to $2 million in AI credits — would attract high-profile professors as judges and big lab sponsors.

“What is the role of a mathematician when AI can solve conjectures faster?” Mathathon organizers initially asked on the event’s website.

The AI-infused premise of Mathathon drew the ire of current and former Caltech mathematicians.

“I found it pretty outrageous, taking $2 million worth of sponsorships from OpenAI and Anthropic (and) partnering with these companies that have been, in my opinion, and many other mathematicians’ opinion, very disrespectful to our field,” said Yujin Kim, a postdoctoral fellow in Princeton University’s math department.

Kim had been critical of OpenAI’s approach to solving elusive mathematics problems in viral social media videos. The companies’ sponsorship of the event “felt like aligning with the empire,” Kim said.

“I can’t imagine [the Mathathon] would go any way other than just essentially button pressing and prompting,” Kim said. “That’s not the culture of mathematics. That’s not how we operate.”

After the backlash, OpenAI pulled its support from the event.

“We recognize that the rapid progress of AI in mathematics is disruptive,” Dan Roberts, OpenAI’s research lead, said in a social media post after the open letter was published. A spokesperson for Anthropic declined to comment.

The updated Mathathon competition will allow participants to use AI, but highly encourage them to use open-source tools that can be modified by the public instead of proprietary models run by private entities like OpenAI.

“We are proud of all of our students for the passion, drive, and maturity they have shown throughout this development,” Caltech spokesperson Emily Velasco said in a statement. “The spirit of open inquiry is central to the scientific process, and we hope to see a continued exchange of ideas as the math community charts its course forward.”

Zhao said he and his fellow organizers are determined to move forward with hosting the event. He said organizers hope the Mathathon will allow students to discover ways to use the technology responsibly, and build a bridge between AI developers and the math community.

AI can act like a shortcut to solving math problems

AI has conjured much debate in the math community, some of which has been overdue, said Dimitri Shlyakhtenko, a UCLA math professor who has followed Mathathon developments but did not sign the open letter.

From the outside, it may look like AI is upending the field by solving high-profile problems that have stumped mathematicians for decades. But the reality is more nuanced, Shlyakhtenko said.

“It is very rare that some result in mathematics is obtained out of nothing,” he said. “It usually builds on a mountain of other works that happen, and usually there’s a community of people that care about a particular set of problems.”

Mathematics problems aren’t about the destination of finding a solution, he said. Rather, mathematicians develop new techniques and understandings along the journey to solve a problem. He likened it to hiking to a waterfall. The end goal is to see the waterfall, but the things you discover along the journey are also quite interesting and of value.

With AI, he said that “what we’re seeing right now is that it is sometimes possible to take a kind of a direct shortcut.”

Some mathematicians worry that using AI to solve problems robs training opportunities from younger mathematicians.

Training problems provide opportunities for graduate students to learn skills and approaches to mathematics, but “if those just get solved, then the motivation to do it is kind of gone, right?” Shlyakhtenko said.

Over the past several months, as the Mathathon drama unfolded, Zhao said he has learned two important lessons: Be ambitious and be humble.

Maintaining the lofty goal of the event — of trying to help unravel the thorny debate of AI’s role in mathematics — has helped the team persist in the face of challenges, Zhao said. He added that it also developed the event into something more than just a fun, competitive weekend. The conversations with mathematicians around the world about the event have also taught him to be wary of flashy statements.

“If we just present ourselves honestly as undergrads who are curious about AI, we actually attract more sympathy,” Zhao said. “We actually attract more mathematicians who are willing to help us.”