California Wildfire Smoke Harms Respiratory Health More than Fine Particulates from Any Other Source, Including Vehicle Emissions

By Jerri-Lynn Scofield, who has worked as a securities lawyer and a derivatives trader. She is currently writing a book about textile artisans.

A new study has found that the smoke that now blankets large parts of California during wildfire season is more toxic to human respiratory systems than any other source of fine particles, including vehicle emissions.

The study, published last week in Nature Communications, covered the period from 1999 through 2012 and examined data for southern California. It concluded that toxic particles arising from wildfires were ten times more likely to lead to hospitalizations than those from any other source.

The study concluded that given the different toxicity of particulate matter – depending on its source – policymakers needed to consider the source of emissions when formulating air quality standards:

Wildfires are becoming more frequent and destructive in a changing climate. Fine particulate matter, PM2.5, in wildfire smoke adversely impacts human health. Recent toxicological studies suggest that wildfire particulate matter may be more toxic than equal doses of ambient PM2.5. Air quality regulations however assume that the toxicity of PM2.5 does not vary across different sources of emission. Assessing whether PM2.5 from wildfires is more or less harmful than PM2.5 from other sources is a pressing public health concern. Here, we isolate the wildfire-specific PM2.5 using a series of statistical approaches and exposure definitions. We found increases in respiratory hospitalizations ranging from 1.3 to up to 10% with a 10 μg m−3 increase in wildfire-specific PM2.5, compared to 0.67 to 1.3% associated with non-wildfire PM2.5. Our conclusions point to the need for air quality policies to consider the variability in PM2.5 impacts on human health according to the sources of emission.

This conclusion is particularly important as California has always led the way among U.S. states in formulating air quality standards.

Climate Change Effects

Climate change has only raised the importance of these issues. Wildfires will become an increasingly common feature as the effects of climate change increase. According to The Guardian:

“We know wildfires are going to become more extreme, due to climate change,” said Rosana Aguilera, a postdoctoral scholar who co-authored the research. “And it’s important that we start to reckon with the health effects of that.”

Aguilera and her colleagues looked at hospital admissions over a 14-year period, from 1999 through 2012, and found that spikes in air pollution during peak fire season in southern California – when fierce Santa Ana winds usually stoke the most destructive wildfires – were correlated with a 10% increase in hospitalizations for respiratory issues.

Since then, wildfires in the west have only gotten more ferocious and destructive – spewing up even more toxic smoke. Six of the largest wildfires on record burned in 2020. And while particulate pollution across the US has been generally declining in recent years due to stricter environmental regulations, pollution in the north-west increased due to wildfires.

Impact of Wildfires on Low-Wage Workers

The Guardian account emphasised the disparate impact of the wildfires on low-wage workers, especially those required to do hard physical labor outdoors during fire season:

The pollution disproportionately impacts low-wage workers, and poor communities of color across the state who are already exposed to high levels of pollution from other sources including factories, highways and refineries. In southern California’s Riverside and Imperial counties, southeast of Los Angeles, farmworkers regularly breathe in pesticide-laden smog. “In our region, the majority of workers have asthma,” said Luz Gallegos, the executive director of the advocacy group Todec. “Their kids have asthma, their parents have asthma. This has been an ongoing crisis.”

During last year’s record-setting wildfires, workers continued to harvest crops under smoke-filled skies. “One woman in our community just collapsed in the field, as she was working,” Gallegos said. She had asthma, and once she was rushed to the hospital, tested positive for Covid-19. “Thank God, she survived,” Gallegos said – but it’s uncertain whether her lungs will be able to handle the continued strain.

“These stories are very, very common,” Gallegos added.

Implications for a Post-COVID World.

The study carries worrying implications  for a post-COVID world, for three reasons. Worsening wildfires will be an increasingly familiar occurrence as climate change accelerates. Even with drastic policy changes, even best case scenarios don’t predict any reversal of climate changes already set in motion.

First worry: many Californians who have survived COVID-19 now suffer impaired lung function, whether they experienced acute symptoms or not. A reminder: these impacts are not confined exclusively to the elderly or otherwise infirm. During an appointment with my opthalmologist in January, I got to taking to the technician who administered some of my eye tests. He was in his early twenties and looked quite fit. He confided that he’d had COVID late in 2020 – what he called a bad case, although I don’t think he was hospitalized – and was just beginning to feel better, after months of recovery. He said he was worried as scans of his lungs showed lingering damage. He said he’d always been active – a runner maybe? I don’t recall exactly. But he was young and lean. I know this is only one example, but there are so many more.

Second worry: the study looked at California only, from 1999 through 2012, stopping nearly a decade ago. Since then, West Coast wildfires have only dramatically worsened. And in future, out- of- control wildfires won’t be confined to the U.S. alone. Other places will – and some already have – experienced them. Take, for example,  Brazil; I wrote about the wildfires then raging in its Pantanal wetland – a place that should be impervious to wildfires – last September (see Brazil’s Pantanal Wetland is On Fire, Joining Other Places Where Wildfires Rage or Have Recently Burned Out of Control). The Pantanal is typically flooded between November and April, during the Brazilian rainy season .

Note that Brazil has also been hard-hit by COVID – and the ravages of the disease have also left many survivors with damaged lungs.

Third, worry: although this study examined the impact of wildfires on respiratory illnesses only, the smoke they produce can also drastically afflict  those who suffer from cardiovascular disease, and thus increase the likelihood of heart attacks or strokes. The Guardian picked up on this point:

Recent research has shown that wildfire smoke can exacerbate not only respiratory illnesses but also heart conditions – triggering heart attacks and strokes, said Mary Prunicki, a Stanford researcher who studies the health impact of air pollution.

Prunicki, who was not involved in the recent study, said there is a growing body of evidence that smoke from the megafires California has seen in recent years is not only bad for our health, it’s “extra-bad – probably worse than some other types of pollution”.

Impaired heart and brain function has also been reported in some COVID survivors.

What Is To Be Done?

The Guardian gestured to the need for California to adopt better wildfire policies. This is particularly important in a post-COVID world, where many people will be less able to cope with the smoke wildfires produce:

Although wildfires are a natural part of California’s landscape, global heating and decades of forest mismanagement have left the region increasingly vulnerable to bigger, more destructive blazes. Researchers said that officials should immediately take steps to curb greenhouse gas emissions to address the climate crisis, and recognize Indigenous ecological expertise in managing fire-prone landscapes.

Solutions could include a return to “prescribed burns” – a technique that hundreds of California’s Native people have used for thousands of years, setting small controlled burns to clear out fire-fueling vegetation and prevent the larger, more toxic blazes that have obliterated homes and neighborhoods.

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  1. Wukchumni

    Solutions could include a return to “prescribed burns” – a technique that hundreds of California’s Native people have used for thousands of years, setting small controlled burns to clear out fire-fueling vegetation and prevent the larger, more toxic blazes that have obliterated homes and neighborhoods.

    There’s really not much snow on the ground here in the southern Sierra, a whole 6 inches worth @ 7k right now, and the prescribed burns that have been done by NPS the past decade around these parts have pretty much been started below that altitude, and what an opportunity to do some in the winter months, but the will & the means to do it and any follow through aren’t there for a myriad of reasons, the smoke would probably drift down into the Central Valley and there’s no way a small amount could be countenanced, although we seem to be ok with massive out of control wildfires that gin up 400 ppm worth of smoke & particulate. (it was 13 ppm here the other day)

    In about an hour i’ll be doing a prescribed burn of sorts in our fire pit, consisting of parts of a dead 150 year old large Buckeye tree that if left to it’s own devices sprawled on the ground would’ve been the basis for 20-25 foot high flames in the summer if a wildfire was to come through, reaching into the canopy of other trees nearby. Instead, there’s merely be a yawning void where it once stood.

    The Castle Fire was pretty much game over for me as far as hiking went from September onward for 3 months, its bad enough just breathing in the gunk, but walking up & down thousands of feet in altitude exacerbates the issue, a no-go zone for me.

  2. David in Santa Cruz

    This problem exists for the entire western U.S. and Canada, not simply in California. This past year we drove from Santa Cruz to the Canadian border to check on our property in the San Juan Islands, and for a thousand miles the entire region was shrouded in heavy, choking, smoke.

    I can only imagine the damage being done to the lungs of those who earn their living outdoors. This is going to be a very serious chronic public health problem that our private for-profit system of care is ill-equipped to treat on the ongoing and long-term basis that it will require.

    1. tegnost

      Not sure if you’re on a ferry served island or an “outer island” as I am, but the tenor of the various islands exposes their various selves through the police blotter
      Here’s a bumper sticker I saw today…
      “Don’t try to change lopez island, let lopez island change you”
      Having read many of your comments I don’t expect you’ll have much trouble here. It’s great, but don’t tell anyone :)
      One bit of advice, it’s a touristy place so expect it to take a while for people to accept that you’re going to be here. When I lived in Friday Harbor it took most of a year before anybody knew my name…

      1. lordkoos

        My wife lived on Lopez for 17 years. She loved it but it’s isolated, and expensive.

        The smoke here in central WA has been terrible for the last decade, except for 2019 when we were spared. Fortunately it’s been only for a few weeks of the year, but between the fires and the pandemic you start to feel like you’re in jail.

  3. Tom Stone

    I have permanent damage from wildfire smoke, so does almost everyone who was in the North Bay for the 2017 fires.
    Visibility in Sebastopol, 15 miles west of the fires, was less than 100 feet at times, in Santa Rosa even less at times.
    I delivered quite a few pickup truck loads of supplies during the emergency and very few people had masks within the first week.
    The long term effects are just starting to show up. look under your bathroom sink and consider what YOU would like to smoke.

  4. Ian Ollmann

    Now would be an excellent time to order air filters for your home, or replace existing air filter components. It seems unlikely to me that California is going to be able to do much about the problem before next fall.

    1. Tom Stone

      Ian, this is going to last a lot longer than this fall.
      The climate has changed and it’s going to get warmer.
      California alone has hundreds of Millions of trees killed by drought or Sudden Oak Death Syndrome.
      The only Bay Area County not at serious risk of a fire at the urban/wildland interface is San Francisco.
      And of course the nightmare of the Hayward/Rogers creek fault letting go with a 6.8 during a high October wind event in a drought year.
      On just the right day of the week and right time of day to make Murphy smile.

  5. Craig H.

    The 2020 wildfire smoke season in northern CA was unusually long after beginning with freak August lightning strike wild fires. In my records the air was unpleasant to breathe for 81 consecutive days. The previous average summer-fall fire season in these parts was 10-25 days of bad air.

    Do not know if that is going to repeat. Not going to find out. I am moving and the reason I am moving is I like to breathe.

  6. Alex Cox

    Controlled burns in California were cancelled last year due to air quality concerns. Meanwhile the wildland firefighters are mainly part-timers or prisoners who get no health insurance.

    The firefighters are heroes and heroines, but the State of California fails them even worse than it fails the rest of its inhabitants.

  7. BlakeFelix

    I wonder how bad the “prescribed burns” are for air quality? I’ll buy that they are less toxic, but how much less I wonder…

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