The Brief

Interest in air filters and purifiers is spiking in Southern California, including questions about how to build a homemade air purifier. Getting clean air is the latest challenge for residents who evacuated to safe areas, only to be forced to endure unhealthy smoky air.

On Friday, a large area in and around Los Angeles was listed as having unhealthy air due to particulate matter from large wildfires that devastated communities this week, according to the federal AirNow air quality monitor.
On AirNow' map, a "red zone" (signaling air quality index values from 151 to 200) stretched from Inglewood in the northwest to Long Beach and Sunset Beach in the southeast.
In the "unhealthy" range of 151 to 200, some people may experience health effects and members of sensitive groups — children and older adults or those with heart or lung disease — "may experience more serious health effects," the Environmental Protection Agency says.

A big worry, experts say, is fine inhalable particulate matter known as PM 2.5 (for 2.5 microns) that can lodge deep into our lungs.

And as researchers at the University of Washington note, "Smaller ultrafine particles (PM 0.1) can pass into the bloodstream and organs, including the brain."

Here's a quick guide to getting cleaner air:

Search filters by their MERV rating

Filters are key, whether you're using them to upgrade your home's HVAC system or put them in an air purifier or a DIY air cleaner. A filter's ability to pull particulates and other matter out of the air are rated by Minimum Efficiency Reporting Values, or MERV. Filters with higher values can catch smaller contaminants like smoke, bacteria and viruses.

A MERV rating of 13 means the filter is efficient at catching items from 0.3 to 1 micron in size: "Bacteria, droplet nuclei (sneeze), most tobacco smoke, insecticide dust," according to the California Air Resources Board, or CARB.

"Upgrading to a filter rated MERV 13 or higher can be especially important during smoky periods to effectively remove fine particle pollution from smoke in the indoor air," the EPA says. It adds that most HVAC systems work fine using MERV 13 filters, as long as the filter is replaced frequently — but if you're in doubt, ask an HVAC technician to be sure.

One thing to remember: If you're using your HVAC system to clean your home's air, it only does so when the unit is running. You can learn more about filter rating systems from LAist here.

An air quality map shows a large part of the Los Angeles metro area with "unhealthy" air, due to large wildfires fueled by strong winds.

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Air Now/ Screenshot by NPR

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Build an air cleaner at home

All you need is a box fan, good air filters and some duct tape, and you're in business.

NPR has previously posted a design and guide to building an air purifying cube known as a Corsi-Rosenthal Box, using four 20-inch MERV 13 filters, a 20-inch box fan and two 20-inch panels of cardboard.

A smaller and more affordable approach is to attach one MERV filter to the back of a box fan, an idea laid out in a website from the Montana group Climate Smart Missoula. The group notes that people using that option should use newer box fans, and be sure the motor is clean to reduce the risk of overheating.

The Centers for Disease Control and Prevention says these DIY purifiers can be effective for a temporary solution, especially if you don't have any other alternatives.

Use HEPA air purifiers and other methods

HEPA (for high-efficiency particulate air) filters are used in many air purifier machines. HEPA is roughly equivalent to a MERV 17 filter, the California Air Resources Board says.

"A well-sealed HEPA filter is more than 99.9% efficient for all sizes of particles," according to the American Society of Heating, Refrigerating, and Air-Conditioning Engineers, or ASHRAE.

If you plan to buy a portable air cleaner or purifier, the EPA says you should make sure it has a HEPA filter. To help your search, California has a table of state-certified air cleaners that lists more than 1,000 products by brand, model number, and type. The EPA also has a guide on matching your room size with the appropriate unit.

Whichever strategy you choose, experts say you should also make sure doors, windows and air ducts are well sealed, to keep out smoke and pollution. You should also drink plenty of water to help ease irritation — and wear a mask if you go outside, as NPR has reported.

More tips on staying healthy

Laist has a guide on how to navigate the unhealthy air here.

Copyright 2025 NPR

Southern California is expected to see the longest heat wave of the season.

The National Weather Service has issued an extreme heat warning for the greater Los Angeles area from Friday through at least next Thursday, and forecasters say it’ll likely extend beyond that.

Temperatures are expected to be in the mid-90s to mid-100s, even in coastal areas.

“Unfortunately, we don't really see an end to it as far as we can tell, and that's probably the biggest thing we wanna highlight, is that while we have had hotter events this season already, this one might be the longest-lasting,” said Ryan Kittell, a meteorologist with the National Weather Service.

Kittell said they expect to see a few daily records to be broken.

Southern California saw a record-breaking 10-day heat wave in the summer of 2022.

What does the hot weather mean for fire risk? 

Forecasters say conditions likely won’t meet the threshold for issuing red flag warnings (extremely dry air and windy conditions), but the risk of fire is still going to be high during the heat wave.

“It’s still concerning, and if a fire were to get started in the wrong area, it could grow pretty fast,” Kittell said. “ We do have a history of large fires in similar environments with similar heat, similar time of the year.”

As of Thursday afternoon, Southern California Edison said nearly 10,000 customers in parts of Riverside County were under consideration for power shutoffs, which are used to reduce the risk of electrical equipment starting a fire.

How do we manage through the heat? 

Kittell said people should make plans to stay cool during the long heat wave, and check in on neighbors who are elderly, or on families with young children.

Officials say residents should limit outdoor activities to the early morning hours, stay in air-conditioned places in the afternoon and evening hours, and stay hydrated.

When Naoko Takei Moore, the author of Simply Donabe, was growing up in Tokyo, some of her earliest memories were of the family donabe.

Donabe, which means “clay pot” in Japanese, is an earthenware cooking vessel that has been part of Japanese home cooking for centuries.

On weekends, her mother would set the donabe on a tabletop burner at the center of the table, with the broth already made and the ingredients prepped. She would let Moore, then about 4, add them to the pot.

"It made me feel like I was cooking it," Moore said. "I was a hero."

Her late mother had one piece of advice about the pot: “Just let the donabe do the work for you."

That’s what Moore wants to do at our latest Cookbook Live at the Crawford in Pasadena on Thursday Oct. 8, in partnership with the James Beard Foundation.

What a donabe can do 

"Just let the donabe do the work for you," Moore's late mother used to say.

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Matt Russell

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Courtesy Naoko Takei Moore

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Because the clay is porous, a donabe heats slowly and retains heat long after the flame is off, allowing savory, umami-rich flavors to build without heavy seasoning. It handles almost anything: hot pots, rice, braises, soups, stews and steamed dishes.

"If you have good ingredients, you really don't need to cover up the flavors with so many different things," Moore said.

In Japan, it's often served as a communal pot meal, set at the center of the table so everyone can cook and eat together.

Donabe in L.A.

When Moore moved to L.A. in 2001, she found that her friends loved sushi and ramen, but thought Japanese home cooking was too complicated. The donabe dinners she hosted changed their minds.

On a trip home to Tokyo, she tasted rice cooked in a donabe made by Nagatani-en, an eighth-generation kiln in Iga founded in 1832.

"Oh my gosh, what is this about this particular donabe?" she remembered thinking. She contacted the kiln and began importing its pots.

Moore's West Hollywood shop, TOIRO, carries an array of artisan donabe that she selects herself.

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Courtesy Naoko Takei Moore

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Moore launched TOIRO in 2008 as an online import business, shipping orders from her basement and teaching donabe classes in her home kitchen. She opened the West Hollywood shop in 2017.

"First I had to start by telling people how to pronounce it," she said. (It's doh-nah-bay.)

Now, she said, major publications print "donabe" without translating it, and in 2015 she co-wrote her first book on the subject. Simply Donabe is her second.

What's cooking Oct. 8

Naoko Takei Moore's new cookbook, Simply Donabe: Japanese One-Pot Recipes.

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Courtesy Naoko Takei Moore

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For Moore, the upcoming cooler weather means hot pot season.

"The season is changing, and it's getting cooler, which I love," she said. "I love making all different kinds of hot pot dishes."

Onstage, she'll make a chicken-and-lemon hot pot from the new book, with sweet saikyo miso, kabocha squash, enoki mushrooms, spinach and thinly sliced lemon.

"I hope you'll be surprised how simple it is," she said. "And I hope you get to smell it."

As the city of Los Angeles continues to struggle to reduce traffic deaths, local officials are planning to use new cameras to detect speeding drivers.

In a Thursday news conference, city leaders said that by the end of the year, cameras at 125 locations throughout the city will all be online. The first cameras will be operational by the end of October.

“Speed is the primary difference between a crash that injures and a crash that kills,” said L.A. Department of Transportation General Manager Laura Rubio-Cornejo at the news conference, held near an elementary school in East Hollywood where crews have installed a camera.

In the last decade, between 250 and 350 people in the city have died every year from traffic collisions. LAPD data from the end of September show that traffic deaths are up 14% compared with last year.

A program launched under former Mayor Eric Garcetti, known as Vision Zero, aimed to reduce traffic fatalities to zero by 2025. Instead, last year, 290 people died in traffic fatalities, exceeding homicides for the third year in a row.

“The implementation of speed safety systems in the city of Los Angeles is as groundbreaking and potentially lifesaving as the implementation of seat belts,” said Damian Kevitt, the head of the nonprofit Streets are for Everyone, which has long advocated for the cameras.

Where are the cameras and how will they work?

Each of the 125 locations will have two cameras monitoring cars traveling in both directions.

You can see an interactive map of camera locations here. LAist reported on the city’s methodology for choosing locations earlier this year.

If a driver is going at least 11 mph above the posted speed limit, a camera will capture a photo of the rear of the vehicle, including the rear license plate.

“This information is and will remain the sole property of the Los Angeles Department of Transportation,” Rubio-Cornejo said. “It cannot be shared with any law enforcement agencies without a court-issued subpoena.”

After the cameras at each of the locations are installed, there will be a 60-day period during which speeding drivers will receive a warning.

Citations and fines, which range from $50 to $500 depending on the severity of the speeding, will follow the warning period.

All warnings, citations and fines will be mailed to the registered owner of the offending vehicle.

Revenue generated from the cameras is required by state legislation to be invested in the city’s efforts to make streets safer.

Evidence from other cities show cameras deter speeding

L.A. is one of several cities permitted to pilot the speed cameras by state legislation authored by then-Assemblymember Laura Friedman.

“We have people who walk around our community every single day, who more and more are the victims of traffic violence from drivers who are driving recklessly and with a wanton disregard for the safety of other people,” said Friedman, who is now a Democratic U.S. Representative for California’s 30th Congressional District.

San Francisco deployed its cameras in May 2025. A year into the program, the city’s transportation agency said it had observed an 80% drop in speeding cars at camera locations. Two-thirds of drivers who were warned about or cited for speeding did not get another ticket, according to the agency.

The data is similar in Oakland, which launched its cameras in January. The Oakland Department of Transportation said that within six months, the number of cars speeding dropped by an average of 70% across the locations compared to baseline data it collected before the cameras were installed.

Other L.A. County cities, including Malibu, Glendale and Long Beach, are also participating in the program.

Gov. Gavin Newsom signed a bill legalizing balcony, or “plug-in,” solar Wednesday.

The device is a twist on rooftop solar: smaller, portable, and relatively inexpensive.

Balcony solar kits consist of just a few panels, an inverter that converts solar energy into the kind used in a home, and cables. In places where the technology is popular, like Germany, it can be plugged into a standard wall outlet.

The new law comes as Californians struggle to pay outsized electricity bills, which have risen substantially in recent years. Plug-in devices open the solar market to renters, people with unsuitable roofs, and those without the money to invest in a rooftop system.

“These small, easy-to-use solar panels will give everyone, including renters, the relief they desperately need on our outrageous energy bills,” said state Senator Scott Wiener (D – San Francisco) in a press release. Wiener authored the legislation.

Plug-in solar panels sit on top of an accessory dwelling unit in Agnes Chan’s backyard in Berkeley, California, for KQED on Aug. 23, 2026.

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The bill received overwhelming bipartisan support from state lawmakers before landing on Newsom’s desk.

Panels can hang from a balcony, out a window, or be tented in the backyard. Existing models range from $300 to $2200, depending on size.

One reason the technology is substantially less expensive than rooftop solar is that it cuts out the costs of installation. Customers themselves set it up, which some have said is straightforward and others have found more challenging than advertised.

California’s law comes with a wrinkle, however. Plug-in solar panels must be certified by an outside safety organization. Since the technology is new in the U.S., there is just one existing certification offered by Underwriters Laboratories. Depending on how manufacturers innovate and roll out products, some may require an electrician’s help to install, while others may be truly “plug and play.”

Electrical experts and other advocates of California’s new law are still calling its passage a massive win, and expect the safety certification to evolve and eventually allow the plug-in panels to connect to a standard wall outlet.

“We are celebrating,” said Cora Stryker, co-founder of plug-in solar advocacy group Bright Saver. “The market is sending a clear signal to manufacturers that they need to develop a California system.”

The new law will exempt plug-in panels from the typical way rooftop solar must be registered with utilities. Instead of paying upwards of a hundred dollars and waiting days to weeks, the new registration process will be free, straightforward, and immediate.

A handful of states have passed similar legislation within the past 18 months. Utah was the first, with a law passed in March 2025.

Ten states now have bills on the books that allow a relatively straightforward process for purchasing and setting up balcony solar systems, including Colorado, Virginia and Maine.

Supporters of the technology include hundreds of environmental and community groups, who argue plug-in solar democratizes access to solar power. They believe adoption by the most populous state would be a boon for the nascent U.S. balcony solar market.

Some of the state’s largest investor-owned utilities, including PG&E and SDG&E opposed the legislation, citing safety and a concern that the systems would shift energy costs to people without solar power in any form.

Labor unions representing firefighters and PG&E employees initially opposed the bill, but took a neutral stance once lawmakers included requirements that systems must comply with state and national electrical codes.

Some Californians have already installed plug-in solar panels, but utilities ask them to complete an interconnection agreement, citing state rules. If done through PG&E for example, representatives from the utility said that process would cost between roughly $100 to $800 and take about an hour. Typically, the approval comes through in three days, PG&E staff said.

Plug-in solar advocates argued that the interconnection process defeated the plug-and-play goal of the technology, and could double or triple its cost.

Their hope is to make the panels as ubiquitous and easy to install as any off-the-shelf appliance dotting the racks of a Home Depot or Costco.

Rupert Mayer installs power inverters on the solar panels at Matthew Milner’s home in Kensington on May 23, 2025.

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KQED

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Proponents of the technology say it can meet up to 20% of a home’s electricity needs and save as much as $500 annually for a small apartment.

The new law outlines several device requirements. The balcony solar systems must not generate more than 1,200 watts per home — enough energy to power a window air-conditioning unit — and offset a customer’s onsite electricity use. They must be certified by an outside safety organization and have a feature that would prevent electricity from feeding back into the grid if there’s a power outage.

Plug-in solar products currently on the market do not yet meet the outlined requirements, and customers therefore must still register the available systems as though they are rooftop solar. The sale of non-compliant systems will become illegal in 2030.

Groups that sponsored the bill said there are a few companies already developing systems meeting the specific California standards, and they expect these models to hit the market in the spring.

The legislation goes into effect in 2027, and sunsets Jan. 1, 2030, “making it a fight that continues,” said Stryker.