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With the ongoing disaster approaching its second week, here’s where things stand.

A week ago, forecasters in Southern California warned residents of Los Angeles that conditions would be dry, windy, and conducive to wildfires. How bad things have gotten, though, has taken everyone by surprise. As of Monday morning, almost 40,000 acres of Los Angeles County have burned in six separate fires, the biggest of which, Palisades and Eaton, have yet to be fully contained. The latest red flag warning, indicating fire weather, won’t expire until Wednesday.
Many have questions about how the second-biggest city in the country is facing such unbelievable devastation (some of these questions, perhaps, being more politically motivated than others). Below, we’ve tried to collect as many answers as possible — including a bit of good news about what lies ahead.
A second Santa Ana wind event is due to set in Monday afternoon. “We’re expecting moderate Santa Ana winds over the next few days, generally in the 20 to 30 [mile per hour] range, gusting to 50, across the mountains and through the canyons,” Eric Drewitz, a meteorologist with the Forest Service, told me on Sunday. Drewitz noted that the winds will be less severe than last week’s, when the fires flared up, but he also anticipates they’ll be “more easterly,” which could blow the fires into new areas. A new red flag warning has been issued through Wednesday, signaling increased fire potential due to low humidity and high winds for several days yet.
If firefighters can prevent new flare-ups and hold back the fires through that wind event, they might be in good shape. By Friday of this week, “it looks like we could have some moderate onshore flow,” Drewitz said, when wet ocean air blows inland, which would help “build back the marine layer” and increase the relative humidity in the region, decreasing the chances of more fires. Information about the Santa Anas at that time is still uncertain — the models have been changing, and the wind is tricky to predict the strength of so far out — but an increase in humidity will at least offer some relief for the battered Ventura and Orange Counties.
The Palisades Fire, the biggest in L.A., ripped through the hilly and affluent area between Santa Monica and Malibu, including the Pacific Palisades neighborhood, the second-most expensive zip code in Los Angeles and home to many celebrities. Structures in Big Rock, a neighborhood in Malibu, have also burned. The fire has also encroached on the I-405 and the Getty Villa, and destroyed at least two homes in Mandeville Canyon, a neighborhood of multimillion-dollar homes. Students at nearby University of California, Los Angeles, were told on Friday to prepare for a possible evacuation.
The Eaton Fire, the second biggest blaze in the area, has killed 16 people in Altadena, a neighborhood near Pasadena, according to the Los Angeles Times, making it one of the deadliest fires in the modern history of California.
The 1,000-acre Kenneth fire is 100% contained but still burning near Calabasas and the gated community of Hidden Hills. The Hurst Fire has burned nearly 800 acres and is 89% contained and is still burning near Sylmar, the northernmost neighborhood in L.A. Though there are no evacuation notices for either the Kenneth or the Hurst fires, residents in the L.A. area should monitor the current conditions as the situation continues to be fluid and develop.
The 43-acre Sunset Fire, which triggered evacuations last week in Hollywood and Hollywood Hills, burned no homes and is 100% contained.
The Lidia Fire, which ignited in a remote area south of Acton, California, on Wednesday afternoon, burned 350 acres of brush and is 100% contained.
It can take years to determine the cause of a fire, and investigations typically don’t begin until after the fire is under control and the area is safe to reenter, Edward Nordskog, a retired fire investigator from the Los Angeles Sheriff’s Department, told Heatmap’s Emily Pontecorvo. He also noted, however, that urban fires are typically easier to pinpoint the cause of than wildland fires due to the availability of witnesses and surveillance footage.
The vast majority of wildfires, 85%, are caused by humans. So far, investigators have ruled out lightning — another common fire-starter — because there were no electrical storms in the area when the fires started. In the case of the Palisades Fire, there were no power lines in the area of the ignition, though investigators are now looking into an electrical transmission tower in Eaton Canyon as the possible cause of the deadly fire in Altadena. There have been rumors that arsonists started the fires, but investigators say that scenario is also pretty unlikely due to the spread of the fires and how remote the ignition areas are.
Officially, 24 people have died, but that tally is likely to rise. California Governor Gavin Newsom said Sunday that he expects “a lot more” deaths will be added to the total in the coming days as search efforts continue.
Incoming President Donald Trump slammed the response to the L.A. fires in a Truth Social post on Sunday morning: “This is one of the worst catastrophes in the history of our Country,” he wrote. “They just can’t put out the fires. What’s wrong with them?”
Though there is much blame going around — not all of it founded in reality — the challenges facing firefighters are immense. Last week, because of strong Santa Ana winds, fire crews could not drop suppressants like water or chemical retardant on the initial blazes. (In strong winds, water and retardant will blow away before they reach the flames on the ground.)
Fighting a fire in an urban or suburban area is also different from fighting one in a remote, wild area. In a true wildfire, crews don’t use much water; firefighters typically contain the blazes by creating breaks — areas cleared of vegetation that starve a fire of fuel and keep it from spreading. In an urban or suburban event, however, firefighters can’t simply hack through a neighborhood, and typically have to use water to fight structure fires. Their priority also shifts from stopping the fire to evacuating and saving people, which means putting out the fire itself has to wait.
What’s more, the L.A. area faced dangerous fire weather going into last week — with wind gusts up to 100 miles per hour and dry air — and the persistence of the Santa Ana winds during firefighting operations through the weekend made it extremely difficult for emergency managers to gain a foothold.
Trump and others have criticized Los Angeles for being unprepared for the fires, given reports that some fire hydrants ran dry or had low pressure during operations in Pacific Palisades. According to the Los Angeles Department of Water and Power, about 20% of hydrants were affected, mostly at higher elevations.
The problem isn’t a lack of preparation, however. It’s that the L.A. wildfires are so large and widespread, the county’s preparations were quickly overwhelmed. “We’re fighting a wildfire with urban water systems, and that is really challenging,” Los Angeles Department of Water and Power CEO Janisse Quiñones said in a news conference last week. When houses burn down, water mains can break open. Civilians also put a strain on the system when they use hoses or sprinkler systems to try to protect their homes.
On Sunday, Judy Chu, the Democratic lawmaker representing Altadena, confirmed that fire officials had told her there was enough water to continue the battle in the days ahead. “I believe that we're in a good place right now,” she told reporters. Newsom, meanwhile, has responded to criticism over the water failure by ordering an investigation into the weak or dry hydrants.
So-called “super soaker” planes have had no problem with water access; they’re scooping directly from the ocean.
Yes. Although aerial support was grounded in the early stages of the wildfires due to severe Santa Ana winds, flights resumed during lulls in the storms last week.
There is a misconception, though, that water and retardant drops “put out” fires; they don’t. Instead, aerial support suppresses a fire so crews can get in close and use traditional methods, like cutting a fire break or spraying water. “All that up in the air, all that’s doing is allowing the firefighters [on the ground] a chance to get in,” Bobbie Scopa, a veteran firefighter and author of the memoir Both Sides of the Fire Line, told me last week.
With winds expected to pick up early this week, aerial firefighting operations may be grounded again. “If you have erratic, unpredictable winds to where you’ve got a gust spread of like 20 to 30 knots,” i.e. 23 to 35 miles per hour, “that becomes dangerous,” Dan Reese, a veteran firefighter and the founder and president of the International Wildfire Consulting Group, told me on Friday.
Because of the direction of the Santa Ana winds, wildfire smoke should mostly blow out to sea. But as winds shift, unhealthy air can blow into populated areas, affecting the health of residents.
Wildfire smoke is unhealthy, period, but urban and suburban smoke like that from the L.A. fires can be particularly detrimental. It’s not just trees and brush immolating in an urban fire, it’s also cars, and batteries, and gas tanks, and plastics, and insulation, and other nasty, chemical-filled things catching fire and sending fumes into the air. PM2.5, the inhalable particulates from wildfire smoke, contributes to thousands of excess deaths annually in the U.S.
You can read Heatmap’s guide to staying safe during extreme smoke events here.
“The bad news is, I’m not seeing any rain chances,” Drewitz, the Forest Service meteorologist, told me on Sunday. Though the marine layer will bring wetter air to the Los Angeles area on Friday, his models showed it’ll be unlikely to form precipitation.
Though some forecasters have signaled potential rain at the end of next week, the general consensus is that the odds for that are low, and that any rain there may be will be too light or short-lived to contribute meaningfully to extinguishing the fires.
The chaparral shrublands around Los Angeles are supposed to burn every 30 to 130 years. “There are high concentrations of terpenes — very flammable oils — in that vegetation; it’s made to burn,” Scopa, the veteran firefighter, told me.
What isn’t normal, though, is the amount of rain Los Angeles got ahead of this past spring — 52.46 inches in the preceding two years, the wettest period in the city’s history since the late 1800s — which was followed by a blisteringly hot summer and a delayed start to this year’s rainy season. Since October, parts of Southern California have received just 10% of their normal rainfall
This “weather whiplash” is caused by a warmer atmosphere, which means that plants will grow explosively due to the influx of rain and then dry out when the drought returns, leaving lots of dry fuels ready and waiting for a spark. “This is really, I would argue, a signature of climate change that is going to be experienced almost everywhere people actually live on Earth,” Daniel Swain, a climate scientist at the University of California, Los Angeles, who authored a new study on the pattern, told The Washington Post.
We know less about how climate change may affect the Santa Anas, though experts have some theories.
At least 12,000 structures have burned so far in the fires, which is already exacerbating the strain on the Los Angeles housing market — one of the country’s tightest even before the fires — as thousands of displaced people look for new places to live. “Dozens and dozens of people are going after the same properties,” one real estate agent told the Los Angeles Times. The city has reminded businesses that price gouging — including raising rental prices more than 10% — during an emergency is against the law.
Los Angeles had a shortage of about 370,000 homes before the fires, and between 2021 and 2023, the county added fewer than 30,000 new units per year. Recovery grants and federal aid can lag, and it often takes more than two years for even the first Housing and Urban Development Disaster Recovery Grants’ expenditures to go out.
My colleague Matthew Zeitlin wrote for Heatmap that the economic impact of the Los Angeles fire is already much higher than that of other fires, such as the 2018 Camp fire, partly because of the value of the Pacific Palisades real estate.
The wildfires may “deal a devastating blow to [California’s] fragile home insurance market,” Heatmap’s Matthew Zeitlin wrote last week. In recent years, home insurers have left California or declined to write new policies, at least partially due to the increased risk of wildfires in the state.
Depending on the extent of the damage from the fires, the coffers of California’s FAIR Plan — which insures homeowners who can’t get insurance otherwise, including many in Pacific Palisades and Altadena — could empty, causing it to seek money from insurers, according to the state’s regulations. As Zeitlin writes, “This would mean that Californians who were able to buy private insurance — because they don’t live in a region of the state that insurers have abandoned — could be on the hook for massive wildfire losses.”
First and foremost, sign up for all relevant emergency alerts. Make sure to turn on the sound on your phone and keep it near you in case of a change in conditions. Pack a “go bag” with essentials and consider filling your gas tank now so that you can evacuate at a moment’s notice if needed. Read our guide on what to do if you get a pre-evacuation or an evacuation notice ahead of time so that you’re not scrambling for information if you get an alert.
The free Watch Duty app has become a go-to resource for people affected by the fires, including friends and family of Angelenos who may themselves be thousands of miles away. The app provides information on fire perimeters, evacuation notices, and power outages. Its employees pull information directly from emergency responders’ radio broadcasts and sometimes beat official sources to disseminating it. If you need an endorsement: Emergency responders rely on the app, too.
There are many scams in the wake of disasters as crooks look to take advantage of desperate people — and those who want to help them. To play it safe, you can use a hub like the one established by GoFundMe, which is actively vetting campaigns related to the L.A. fires. If you’re looking to volunteer your time, make a donation of clothing or food, or if you’re able to foster animals the fire has displaced, you can use this handy database from the Mutual Aid Network L.A. There are also many national organizations, such as the Red Cross, that you can connect with if you want to help.
The City of Los Angeles and the Los Angeles Fire Department have asked that do-gooders not bring donations directly to fire stations or shelters; such actions can interfere with emergency operations. Their website provides more information about how you can help — productively — on their website.
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Facing down a sea change, the automaker has staked its next EV bet on a compact, sporty pickup.
“Full fathom five, your father lies,” the invisible spirit Ariel sings early in The Tempest, as a handsome and grieving prince listens, rapt. The song tells of a shipwrecked skeleton transforming into something else — its eyes have become pearls, and its bones pink coral — as it undergoes, yes, a “sea change.” It is the first time that phrase appears in the English language.
Ford is now facing its own kind of sea change. Over the past decade, the automaker has doubled down on its most profitable and exciting vehicles — pickups, SUVs, and the Mustang muscle car — and dropped from its line-up the cheap, boring cars that once made it famous. It embraced, then backed off, the transition to electric vehicles, in part because it failed to make money from them; and it began to reckon with the surge of cheaper, cleaner, and “far superior” EVs from Chinese producers that are transforming global auto markets around the world.
Locked into its aging but reliable line-up, yet unable to innovate at the low end, Ford might seem like the epitome of a company facing disruptive innovation. No wonder its stock has traded flat from where it was five years ago — even as the broader market has surged by more than 70%.
Its solution is an EV skunkworks, run by Tesla alumni, where it can develop a new “universal EV platform” to undergird future vehicles. Today, we got a peek at the first car to emerge from that secret shop: an all-electric compact pickup that will hit the roads by the end of next year. Its name? The Ford Fathom.
We know very little about the Fathom, as our correspondent Andrew Moseman wrote today. It will retail for just over $28,000, and even with mandatory delivery costs and other add-ons will stick to this side of $30,000. That makes it only a smidge more expensive than the gas-burning Ford Maverick, a sporty, compact, and popular pickup that starts around $27,000.
Ford promises that the Fathom will have as much seating capacity as Toyota’s RAV4, America’s best-selling car that isn’t a truck. (Ford’s own F-150, of course, holds the true No. 1 spot.) Those dimensions suggest the Fathom will sport a four-door crew cab, like the Maverick, making it more acceptable to families with kids — or young professionals who want to give their friends rides on the weekend. It will also have a frunk.
Beyond that, though, we don’t know much. We don’t know its range, for instance, and its price point shouldn’t inspire too much confidence on that front. Nor do we know, frankly, whether Ford can pull it off: When the automaker announced its first electric truck, the F-150 Lightning, in 2021, it claimed a price point of less than $40,000. Eighteen months of inflation later, it actually sold them for closer to $55,000 — and it still lost money on every EV that it made. Fixing the latter problem is part of why the skunkworks exists in the first place, and Ford now has an additional half-decade of experience making EVs. But consumers hoping for a miraculously priced electric pickup from the Blue Oval have been burned before.
If the Fathom disappoints, though, then consumers will soon have other options. The American car market is about to be deluged with sporty, compact pickup trucks — a welcome change from just a few years ago, when the segment was almost entirely dominated by mid-size and half-ton models. The Jeff Bezos-backed startup Slate will start delivering two-door, all-electric pickups starting at $25,000 at the end of this year. The automaker Stellantis, which owns the Dodge and Jeep brands, says it wants to bring another compact pickup — it’s almost more of a ute — called the Rampage to North America soon.
That’s welcome news for me — I love these little trucks — but I’m a little worried I’ll be outside my pickup-buying years by the time they actually make it to market. In the meantime, I’ll keep you posted on other updates about the Fathom. Will “sea nymphs hourly ring its knell”? No, but it will have Apple CarPlay and Android Auto.
The company confirmed its plans to market research company Cleanview.
The data center buildout has hit a new inflection point. It has long been true that artificial intelligence is fueling climate change by driving up power demand; more recently, tech companies have started directly financing new natural gas plants in their quest for AI glory. Now one is backing the biggest fossil fuel-fired power plant ever to exist in the United States — exclusively to power an AI data center complex.
That company is Amazon, according to the market research company Cleanview, which reported on Friday that the tech giant is building an AI data center campus in Texas powered by an up to 7.65-gigawatt off-grid natural gas plant.
That’s larger than any other power plant in the country — fossil or otherwise. The next biggest plant is the Grand Coulee hydroelectric plant in Washington State, at 7 gigawatts, followed by Arizona’s 4-gigawatt Palo Verde nuclear plant, and the West Count Energy Center, a 3.7-gigawatt natural gas plant in Florida.
The new power plant’s developer, Pacifico Energy, announced in January that it had secured permits from Texas regulators for the project, dubbed “GW Ranch.” The site is also permitted for up to 750 megawatts of solar and 1.8 gigawatts of battery energy storage.
It was not clear who the customer for all this energy would be until earlier this week, when Cleanview uncovered construction permits Amazon filed showing that the company owned the GW Ranch site. The company confirmed to Cleanview that it acquired the site and planned to buy power from Pacifico’s plant.
Not only will this natural gas plant be larger than the one in Florida, it will also use far less efficient technology. Pacifico’s permit says it plans to build 35 “simple cycle” generating units, which are typically installed in rarely-used peaker power plants and waste a lot more fuel potential than the modern “combined cycle” natural gas plants that serve as baseload power for the grid today. These more efficient turbines are essentially on backorder for years, and power-hungry developers have increasingly turned to the simpler versions as a quick fix as they race to bring facilities online.
According to its permit, the GW Ranch plant is allowed to emit as much as 33 million tons of CO2 per year. That’s twice as much as the most-polluting power plant in the country, the James H. Miller Jr. coal plant in Alabama, emitted in 2023, the most recent year for which data is available.
In a statement to Cleanview, an Amazon spokesperson said the company “believes in paying the full costs of powering our operations,” and that this Texas project “does just that: it’s powered by new on-site generation that won’t raise electricity costs for Texas families and designed to transition to grid-connected service as interconnection timelines allow.”
Some researchers disagree on that point, however. In an opinion piece for Utility Dive, Energy Innovation director Jeffrey Rissman and senior fellow Eric Gimon argue that the proliferation of off-grid natural gas generation for data centers will increase costs for regular people more than if the data centers connected to the grid, because they will be competing with utility companies for gas supply. “Data centers can buy gas in bulk and sign long-term contracts (as we’ve seen in Texas, Pennsylvania and New Mexico), giving them access to cheap gas, even if this unfairly drives up prices for everyone else,” they write.
Jane Flegal, a senior fellow at the Searchlight Institute, has also argued that building off-grid natural gas plants to serve data centers locks in emissions for decades because the plants don’t face competitive pressure from other resources. When a new natural gas plant is hooked up to the grid, by contrast, there’s a far greater chance that cheaper, cleaner resources will displace its generation over time.
The Rhodium Group recently developed a scoring system to help investors differentiate between projects that are likely to accelerate the energy transition, those that will have little effect one way or the other, and those that will actively slow it down. They used it to assess options for powering data centers, and found that off grid natural gas plants scored the worst, falling at the bottom of the latter category.
Regardless, Amazon still, somehow, asserts that it is committed to achieve net zero emissions by 2040.
The smoke pouring into Seattle from Spokane is particularly bad, but there’s also no such thing as good smoke.
I wrote this story from inside a cloud of smoke. Owing to some funky meteorology in the Seattle area this week — a pressure ridge paired with a thermal trough — the region’s usual westerly winds reversed, causing smoke from the fires burning in the eastern half of the state to pour through the mountain passes and river valleys of the Cascades and pool over the populous Puget Sound lowlands, where I live.
Though it’s cleared up some today, I’m still running my air purifier on full blast because I know what’s in the lingering smoke. Unlike the still blazing wildfires in Ontario that are burning through mostly uninhabited forests, the smoke in the Seattle area this week came to us partially from Spokane, where the Old Trails fire razed at least 700 buildings and homes last weekend. That means that beyond the usual organic matter associated with wildfire smoke, the pollution that has hung over Seattle has likely also contained particles and chemicals from burned plastics, batteries, cars, and household appliances.
But how can the average person be sure whether their wildfire smoke is the bad kind or the worse kind? (At least assuming that well-adjusted people do not obsessively watch the animations on AirNow.Gov, as I do.) I turned to Coty Jen, an associate professor of chemical engineering, and Albert Presto, a research professor of mechanical engineering, both of Carnegie Mellon University, to learn more about the chemistry of wildfire smoke.
“There is no safe smoke,” Jen said, setting me straight immediately. “It’s all bad. It will piss your body off.”
While it’s true that some smoke is more toxic than other smoke, what you might call the “all natural, organic” variety will still spike hospital emission rates and exacerbate pre-existing respiratory diseases, even if it is mostly burning trees.
Under ideal conditions, when cellulose or lignin — the main structural components of trees and plants as well as leaf litter and soil, the largest sources of carbon during a forest fire — heat up and combust, the chemical reaction creates carbon dioxide, water, heat, and light. But wildfires don’t burn cleanly, and the chemical reactions often stall midway through that process due to things like oxygen availability and temperature variation, producing intermediate products like carbon monoxide or partially broken-down bits of carbon, often called soot. The tiniest of these particles can be smaller than 2.5 micrometers across — 30 or more could fit across the width of a human hair — and are measured collectively as PM2.5, a catch-all term that refers to the size of the particle rather than what it is. What’s important, though, is that these particles are small enough to penetrate deep into our lungs and potentially enter our bloodstream, factors that add to the known mortality associated with PM2.5 exposure.
Different kinds of forests create different emissions — heavy duff, or leaf litter, which is common in pine forests, creates some of the densest smoke conditions. Wetter fuels also burn “dirtier,” creating more pollution. Different topographies also impact air quality in myriad ways; it’s no surprise that some of the worst pollution from the Spokane wildfires pooled in mountain valleys as a warm overhead layer of air trapped the particles near the ground.
Even “natural” wildfires can be extra toxic; burning eucalyptus, which grows in Southern California, is not something you want to inhale. Pine smoke can cause mutations in bacterial DNA, a common lab test for a substance’s potential to cause cancer. Wildfires that smolder are worse than those that burn fast; researchers have found that PM2.5 can be up to 70 times higher when fuels aren’t actively on fire. “You can even see this if you’ve ever built a fire yourself,” Presto explained. “There’s a period where everything is big and flaming, and then, if you’re burning a log, it eventually goes down to smoldering. The emissions are different.”
In the case of something like a house burning down in a wildfire, however, it’s not only cellulose and lignin combusting. “We’re good at engineering materials that are extremely robust, but when they burn, they release very exotic compounds,” Jen said. She pointed to the common plastic PVC, which is used for everything from exterior siding to plumbing and window frames. When it combusts, PVC releases chlorine, “which is very bad for you,” Jen told me. “It’s like how bleach is bad for you — it’s a pretty nasty chlorine compound. PVC isn’t releasing bleach, but it is releasing radical chlorine molecules that produce some crazy compounds.”
If you’re following a smoke event at home, the answer is “not really.” PM2.5 is measured in micrograms per cubic meter, which tells us how much small stuff is floating around, but not what that small stuff is. “It is pretty difficult to measure all the different compounds that wildfires, or broadly any pollution, will emit,” Jen said. “The easiest way to quantify it is to literally suck air onto a filter and measure how heavy it got.”
Measuring what exactly is in that mass requires instruments that cost in the ballpark of half a million dollars, which is not financially feasible at every air monitoring station, Jen went on. But while there are certainly academic applications for that kind of knowledge, a person trying to decide whether or not to go for their run in wildfire smoke doesn’t need that level of granularity.
“Some smoke is definitely more dangerous,” Jen said. “But as innocent bystanders, it’s not like we can pick and choose what smoke floats over to us. You just have to live with it, so the best mentality is to treat all smoke as bad.”
In a 2026 Science Advances study that attributed more than 24,000 deaths per year to wildfire smoke in the U.S., researchers found no safe threshold for PM2.5 exposure. Every 0.1 microgram per cubic meter increase in a county’s average annual PM2.5 from smoke was associated with nearly 5,600 excess deaths nationwide, even though most counties saw only trace amounts of smoke — about 0.4 micrograms per cubic meter a year. While it’s “orange sky” days, when the pollution spikes into triple-digit AQI numbers, that get the most media attention, even low exposure that you can’t smell or even see can be affecting your health.
PM2.5 is just one component of wildfire smoke — the other is gases, including benzene and formaldehyde. Many gases chemically transform as they move from where the fire is to where you inhale them. “The atmosphere is extremely oxidizing — it likes to add oxygen molecules onto compounds,” Jen said.
Some of those compounds react faster than others, “so it depends how downwind you are,” Jen went on. That’s why people closer to a wildfire — maybe a day or less downwind — get the distinctive campfire smell, mainly from the “young” vapors and volatile organic compounds. But for people on the East Coast who were subject to the Ontario smoke several weeks ago, the smoke had to travel several days to reach places like Pittsburgh and New York, and by then the sharper-smelling compounds had transformed into new pollutants like ozone.
The AQI only measures a few specific gases that are considered “criteria pollutants” under the Clean Air Act, which means, as Presto told me, “during these fires, you could emit a whole bunch of different other gases that don’t have an AQI number.”
Instead, you can look at the PM2.5 number to get the gist of how prevalent wildfire gases are. “If your PM 2.5 is high, it’s impossible for the bad gasses to be low,” Jen said. “The way we think about it is, there’s a bunch of junk on the particle, and if the same junk’s not also in the gas, it will evaporate off the particle into the gas. They always exist together.”
You might notice by now that I’ve written little about the actual AQI number, that score that appears on your weather app and runs from zero to 500 (or, confusingly, even higher). That’s because while the AQI is a great communication tool, it doesn’t offer us much in the way of the science of wildfire smoke.
The AQI measures five different pollutants — PM2.5, ozone, carbon monoxide, sulfur dioxide, and nitrogen dioxide — with the EPA setting specific concentration thresholds for each one, as my colleague Emily Pontecorvo has explained. “If local concentrations of any one of them tick up above those protective standards, the AQI will jump from green to a more alarming color,” she wrote. “The higher the level of pollution is, the higher the AQI and the darker the color will be.”
If you want to impress your friends, though, you ought to zero in specifically on the PM2.5 concentration — again, because the prevalence of the tiniest particulates is a good indicator of all the other gunk you can assume is in the air, too. (You can find the specific PM2.5 concentration usually by clicking for more information about the AQI on your weather app or checking IQ Air’s widget.) For example, at the time of this writing, my local PM2.5 concentration is 50 micrograms per cubic meter, more than triple the World Health Organization’s 15 micrograms per cubic meter threshold for 24-hour exposure. (The EPA’s 24-hour threshold is much more lenient, at 35 micrograms per cubic meter.)
When I asked Jen how she stays sane knowing all she knows about smoke exposure, she laughed. “I have just generally become more terrified of all campfires and all barbecues, but people already think I’m weird, so I might as well add to it,” she told me.
In all seriousness, though, she told me the answer is air filters, and her confidence in their ability to work. When wildfire smoke rolled through Pittsburgh, she had two running that she moved from room-to-room with her family, as well as a whole-house air filter. “We were getting PM2.5 concentrations in our house of about 80 micrograms per cubic meter when it was 150 outside,” she said. “But with the air filter on, we could drop that down to less than eight.”
Jen pointed out, though, that many people do not run their air filters properly. Filters are rated at their highest blower level, “so for them to be effective, you need to crank them to their highest setting to get all the air through,” she said. Most people keep their filters on auto or low because they’re so loud — myself included, until I learned otherwise.
Additionally, while an air filter is a rather large appliance, it really ought to be placed in the center of your room to be the most efficient, rather than up against a wall. (Again, my bad.) “When these wildfire events happen, the most effective place for the air filter is where you are, and you have to run it loud, which kind of sucks,” Jen said. “But it is better than breathing in gross air.”