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  1. As climate change fuels large wildfires, the pollution they're releasing is making Americans sick and undermining decades of progress in cleaning the air.

    SANTA ROSA, Calif. — As the deadliest fires in California history swept through leafy neighborhoods here, Kathleen Sarmento fled her home in the dark, drove to an evacuation center and began setting up a medical triage unit. Patients with burns and other severe injuries were dispatched to hospitals. She set about treating many people whose symptoms resulted from exposure to polluted air and heavy smoke.

    This story was produced through a partnership between Climate Central and Kaiser Health News with support from the Bill Lane Center for the American West at Stanford University. Kaiser Health News/California Healthline senior correspondent Barbara Feder Ostrov contributed reporting from Santa Rosa.

    “People were coming in with headaches. I had one. My eyes were burning,” said Sarmento, the director of nursing at Santa Rosa Community Health, which provides health care for those who cannot afford it. But respiratory problems — coughs and shortness of breath — were among the biggest risks. “We made sure everyone had a mask.”

    More than half of the evacuees at the shelter that October night were elderly, some from nursing homes who needed oxygen 24/7. Sarmento scrambled to find regulators for oxygen tanks that were otherwise useless. It was a chaotic night — but what came to worry her most were the weeks and months ahead.

    “It looked like it was snowing for days,” Sarmento said of the falling ash. “People really need to take the smoke seriously. You’ve got cars exploding, tires burning. There has to be some long-term effect” on people’s health.

    From Puget Sound to Disneyland and east over the Rockies, Americans have coughed and wheezed, rushed to emergency rooms and shut themselves indoors this year as pollution from wildfires darkened skies and rained soot across the landscape. Even to healthy people, it can make breathing a miserable, chest-heaving experience. To the elderly, the young and the frail, the pollution can be disabling or deadly.

    Even though the nation has greatly improved air quality over the last 40 years through environmental regulations and technological improvements, the increasing frequency of large wildfires now undermines that progress, releasing copious pollutants that spread far and wide through the air and linger long after the fires are extinguished.

    Views of San Francisco's skyline are smoke-filled on the morning of Oct. 9 as multiple wildfires burn in Mendocino and Sonoma counties.
    Credit: Amy Graff/SF Gate

    Scientists say climate change, degraded ecosystems and the fickleness of the weather have been amplifying fires in forests, grasslands and neighborhoods throughout the West. Nine times more western forestland is burning in large fires each year on average now than 30 years ago, according to calculations by two leading scientists.

    The blazes create smoke waves — pulses of pollution containing everything from charred plastic residue to soot to other small particles that lodge deep in the lungs. They can trigger short-term ailments, such as coughing; worsen chronic diseases, such as asthma; and lead to long-term damage, including cancer.

    The effect of the fires in Northern California’s wine country, which destroyed thousands of homes and killed 43 people, went well beyond the burn zone. The smoke choked the San Francisco Bay Area, home to 7 million people in nine counties, for days.

    Colette Hatch, 75, of Santa Rosa, who suffers from lung disease and uses a nebulizer daily, evacuated to her daughter’s home in Sunnyvale, in Silicon Valley, when the fires came. But even nearly 100 miles away, Hatch said she struggled to breathe, coughing so hard she couldn’t sleep.

    Wafting beyond Oakland and Livermore in the East Bay, the smoke headed into California’s agricultural heartland, the Sacramento and San Joaquin valleys.

    Known collectively as the Central Valley, it stretches for hundreds of miles roughly north to south, bracketed by mountain ranges that trap some of the dirtiest air in America. Increasingly, wildfires like the ones in Northern California’s wine country funnel smoke into the chute, significantly raising the pollution levels in places as far away as Fresno.

    Climate Central, a research and journalism nonprofit, examined air district data from California’s Sacramento and San Joaquin valleys. The analysis showed that while the number of heavily polluted days is falling overall each year on average — those days are occurring more frequently during the peak fire season. The researchers say wildfire smoke is to blame.

    Read the full Climate Central report here.

    Monitors in the San Joaquin Valley and San Francisco Bay Area showed levels spiked in October as the wine country fires sullied skies.

    With large wildfires on the rise, smoke and the attendant breathing ailments seemed everywhere this year. In September, smoke from fires burning in California, the Pacific Northwest and Montana pushed as far east as Pennsylvania. Smoke triggered emergency declarations in Washington state and California. The Evergreen State was experiencing few fires of its own in July when it was hit by smoke waves that poured across the Canadian border. And smoke returned to much of the northwest in August and September as fires broke out in the Cascades and the Columbia Gorge.

    “I remember waking up one morning and the sky was orangey-red and there was ash falling out of the sky,” said Jeremy Hess, a researcher and physician at the University of Washington in Seattle. “This summer was very busy for us in the emergency department and we were often over capacity. If it wasn’t the smoke, it was the heat,” Hess said.

    As World Warms, Environment And Health Suffer

    The blazes came after record-breaking late summer heat dried out grass that had flourished following record-breaking winter rains — both forms of extreme weather that are worsened by global warming. In addition, a high pressure system over the Pacific fanned the flames by driving unusually hot and powerful seasonal winds into Northern California from the dry highlands of Nevada.

    The immediate precipitant may have been sparks from power lines, although investigations into the causes are ongoing. But a changing climate helped fuel the blazes.

    “Climate change was not the cause but it’s definitely an ingredient,” said Park Williams, a climate and ecology researcher at Columbia University’s Lamont-Doherty Earth Observatory. And that means worse is to come.

    Williams said there was a clear connection between the nearly 2 degrees Fahrenheit overall increase in global temperature since the late 1800s and the severity of these and other fires. (Warming in the West has been outpacing the global average in recent decades because of natural cycles.)

    “Fire really responds strongly to even that small of a change of temperature,” said Williams, whose assessment of global warming’s role in the wine country fires is shared by other experts.

    Read the full Climate Central report here.

    Environmentally, the fires are a double whammy: They destroy trees that help to slow global warming by absorbing heat-trapping carbon dioxide as they grow. They also release carbon dioxide stored within, as well as black carbon that melts snow and ice.

    Research indicated in 2015 that large fires had helped turn California’s forests and other lands into polluters, releasing more carbon to the atmosphere than they suck back in. The state’s wildlands released more heat-trapping pollution from 2001 through 2010 than Vermont’s entire economy. Rising temperatures aren’t the only cause — the forests are overloaded with fuel following more than a century of aggressive firefighting.

    While public attention has tended to focus on other health risks from climate change such as heat stroke in summer and the spread of mosquito-borne diseases northward, the effects of smoke pollution have been gaining more attention following dramatic and widespread wildfires.

    The most dangerous pollution from wildfires is fine soot — “really small particles that we know can get into the lungs,” said Colleen Reid, a geographer at the University of Colorado who researches climate change and human health. It’s known as PM2.5, meaning “particulate matter” that’s less than 2.5 microns wide, only visible using microscopes.

    It can nestle into lung tissue and pass into the bloodstream, contributing to an array of health problems including infections and, potentially, heart attacks.

    Ed Corn sifts through the ashes of his former home in Santa Rosa’s Coffey Park neighborhood. “I can definitely taste the toxins in my throat and the back of my tongue,” he said.
    Credit: Heidi de Marco/Kaiser Health News

    Symptoms related to smoke waves may not be diagnosed right away, making it hard to recognize the role a fire may have played in an illness or death. Reid led an analysis published a year ago based on hundreds of studies into fire pollution’s health effects. The clearest links shown in the studies were between PM2.5 and asthma and other breathing problems; links to heart disease were less conclusive.

    Researchers from leading American universities examined fire pollution across the West, finding that two of every three counties in the region suffered at least one smoke wave from 2004 through 2009. When they correlated those findings with medical data, they found a 7 percent jump in breathing-related hospitalizations after smoke levels were most extreme.

    “An acute fire lasting, for example, days to weeks, may not show up as an immediate problem but as health problems that may occur over a time span of weeks or months,” said Loretta Mickley, a Harvard researcher who worked on the study.

    This Summer In California

    Elva Hernandez, 51, has lived in the San Joaquin Valley most of her life. She’s suffered from asthma since she was 10. This summer she was stuck inside her house for several weeks as smoke waves suffocated her neighborhood in the small town of Kerman, Calif., near Fresno.

    “The smell, all the dust, the smoke, the smog, everything, it’s just — you can’t breathe,” said Hernandez, a stay-at-home mom whose husband analyzes lab samples at a hospital. “You can’t live your life normally.”

    The San Joaquin Valley is home to 4 million people, many of them poor. One in six children suffers from asthma. Poor people often are most affected by air pollution, partly because they tend to live in more drafty housing in more polluted neighborhoods.

    But enforcement of federal regulations dating to the Nixon administration has been reducing air pollution from fossil fuels and fertilizers in the valley, requiring cleaner engines for trucks and the replacement of outdated equipment on farms.

    “We’ve been seeing a lot of positive trends,” said Jon Klassen, manager of the air monitoring team at the San Joaquin Valley Air Pollution Control District. At the same time, “there’s a lot more emissions coming from these fires. They’re uncontrollable. They’re very difficult to deal with.”

    Read the full Climate Central report here.

    Research looking at air pollution levels helps explain why people like Hernandez are suffering more during fire seasons. The Climate Central analysis of San Joaquin Valley air data showed that while the number of days each year on which levels of PM2.5 exceeded federal standards declined by about 45 percent overall from 2000 to 2016, they increased by almost a third during the peak summer fire season.

    In the Sacramento Valley to the north, summer fire season pollution has been responsible for about 40 percent of the days when federal standards for PM2.5 pollution were exceeded in recent years. That’s up from less than a tenth of them earlier this century, the researchers found.

    Wildfires also release toxic material and chemicals that react in the atmosphere to form ozone pollution, which can hang over neighborhoods as haze. Ozone irritates lungs and throats, triggers shortness of breath and aggravates diseases like bronchitis, emphysema, and asthma.

    Read the full Climate Central report here.

    Hernandez’s asthma doctor, Praveen Buddiga, who operates his own practice in nearby Fresno, treated patients with oxygen and medicine during September fires in the Sierra Nevada mountains, which straddle California and Nevada. He did so again following the wine country fires in October. For asthmatics, the onslaughts of fire pollution are “like pouring a little salt into the wounds,” he said.

    Buddiga suggests his patients limit their time outside, drive with windows rolled up and wear masks when smoke waves hit. Better yet, he advises them to leave the area if possible until the smoke clears.

    But risks can be difficult to gauge for patients and experts who want to offer precautions. Scientists who sampled pollution from wildfires using a NASA jet reported in June that fire pollution is being “significantly underestimated” by the federal government. While fleets of mobile air monitors are deployed near fires to help government agencies project the movement of smoke waves, the network of permanent monitors is sparse.

    “We have no real good way of communicating to people, ‘Hey, the wildfire smoke is really bad in these spots, and this is where you take precautions,’” said Rob Carlmark, a weathercaster with ABC10 in Sacramento whose audience stretches from Bay Area cities to Lake Tahoe at the Nevada border.

    Absent local smoke pollution data, he tells viewers, “The best smoke detector is your nose.”

    Lighting Up To Protect Lungs — and the Planet

    Josh Bien wore a heavy pack and held a hoe in one hand. Using the other, the firefighter dripped a burning mixture of diesel fuel and gasoline on the forest floor from a spouted canister. Saplings and beds of pine needles sizzled and burned around him in a national forest in the Sierra Nevada, an hour’s drive east of Fresno.

    Like smoke from suburban fires in the San Francisco Bay Area, that from large wildfires in the forest of this 600-mile mountain range can travel into the Central Valley. A spate of large fires in August and September created heavy smoke that suffocated foothills towns and drove people like Elva Hernandez indoors.

    Firefighter Josh Biel igniting the forest floor during a prescribed burn in the Sierra National Forest
    Credit: John Upton/Climate Central

    Devastating forest fire seasons in recent years have prompted research pointing to the need for more prescribed burns like this one. They’re set and managed by firefighters and foresters and guided by computer models that predict the spread of fires and their smoke. They’re aimed at removing highly flammable undergrowth and spare the mature trees.

    “You can either do it on your terms,” said Adam Hernandez, a prescribed fire and fuels management officer with the U.S. Forest Service, as gray smoke billowed around, “or you wait for that wildfire to come and it does it on its terms — and then you’re in a bad way.”

    Small fires used to burn regularly through the understories of the Sierra Nevada’s forests, started by lightning and native tribes. That changed after the Native Americans were forced from the mountain range, followed by more than a century of logging and aggressive firefighting.  Those activities replaced stands of large, fire-resistant trees with thickets of smaller ones, building up fuel for enormous blazes.

    “When you have some of these extreme wildfires, you’re creating more harmful emissions,” said Jonathan Long, an ecologist with the U.S. Forest Service. Extreme fires burn larger areas and their flames jump from forest floors to incinerate canopies, producing heavy black smoke and killing mature trees. “We think taking the medicine in small doses is a lot healthier.”

    The excessive undergrowth amplified the impact of California’s recent drought — there was too little water for so many trees. More than 100 million trees may have died across the Sierra Nevada in recent years. The dead trees can provide nesting cavities and their logs create important habitat for wildlife, but some scientists fear they may also intensify fires after they topple into desiccated piles.

    Trees killed by the effects of drought in the Sierra National Forest
    Credit: John Upton/Climate Central

    The federal government has been striking agreements with state agencies to use more prescribed burns and take other steps to better manage forests. In January, California released an ambitious draft plan to restore forests over the decades to come — through a focus on prescribed burns — with the goal of reducing pollution from wildfires.

    “We’re trying to ensure that we have healthy, resilient forests that are net sinks of carbon so that they’re storing more carbon than they’re releasing,” said Russ Henly, a California Natural Resources Agency official who helped draft the plan. By 2020, the plan seeks to double the amount of land treated using prescribed burns to 35,000 acres a year.

    With so many local, state and federal agencies overseeing environmental rules and owning land in California, the state says coordination will be key. For example, the San Joaquin Valley Air Pollution Control District can prevent national parks and other landowners from conducting prescribed burns when pollution levels will be affected — which is most of the time.

    Mindful of the growing danger of big blazes, the air district has become more accommodating of prescribed fires. Still, finding the money to pay for the work remains a challenge.

    Some members of Congress have pushed logging as a way to ease forest fires, though that approach could have the opposite effect: Trees valued by loggers tend to be the largest and most fire-resistant. Troublesome small trees and dead ones have little value other than as fuel for power plants, and even then they’re generally too expensive to gather. Low natural gas prices have been forcing the closure of biomass power plants, which are fueled with wood.

    Even if the money is found to improve forest management, climate change will likely limit the progress from improved forest management, said Christopher Field, an ecology professor at Stanford University. The fire season will continue to lengthen. Landscapes will continue to dry out. “The challenge we still face is how to get out of decades of managing forests in ways that increase, rather than decrease, fire risk,” he said.

    Field oversaw a survey dealing with Sierra Nevada forests completed by 75 academics, government officials and nonprofit and industry employees. While most agreed that prescribed burns and other approaches can lock carbon into the mountain’s ecosystems, they warned it will be difficult to overcome the losses from wildfires as temperatures rise.

    California doesn’t include carbon losses from forest fires when it tallies its progress toward reducing climate pollution. But amid the burning, logging and clearing of forests from Indonesia to the Amazon and the Congo, destructive fires in the forestlands of a U.S. state that has some of the world’s most ambitious climate goals are contributing to the problem.

    And, in the process, they are making people sick.

  2. Research Report by Climate Central
    November 2017


    Read "Breathing Fire," our feature story on fire pollution

    Smoke pollution is leading to serious public health impacts as large wildfires across the American West become more frequent and destructive. These fires are undermining progress made during recent decades in reducing pollution from tailpipes, power plants, and other industrial sources. The increasing frequency and area burned by large fires is linked to human-caused climate change as well as other environmental changes.

    Climate Central analyzed air quality trends from 2000 through 2016 in two large California air basins that are heavily affected by smoke pollution. The analysis focused on particulate matter (PM2.5), a dangerous air pollutant. We found that while the air is getting cleaner overall in recent years, it’s getting dirtier during the fire season —  a season that research has shown is growing longer in the western United States.

    California’s Central Valley — Climate Central Analysis

    The Central Valley is a large, flat region that dominates California’s geographic center. The valley comprises some 11 percent of the state’s land area and includes population centers such as Sacramento and Fresno, but the majority of the region is made up of farmland — some of the most productive on the planet. 

    Central Valley air quality was analyzed because the region is heavily affected by air pollution  that is produced within an even larger geographical area. Bounded by mountain ranges to both the east and the west, the valley’s geographical and meteorological features combine with industrial activity such as truck traffic to contribute to these high levels of pollution. Some of the pollution is generated within the valley, while other pollution sources include wildfires burning along the coast to the west and in the Sierra Nevada mountain range to the east. 

    Wildfires are a source of an especially problematic type of air pollutant known as PM2.5 (“particulate matter” less than 2.5 microns in diameter), which can become lodged in lungs and cause or exacerbate a wide array of health problems such as asthma and heart disease. Emerging evidence suggests PM2.5 could also be linked to premature births. Other PM2.5 sources include a wide variety of industrial and agricultural activities. To protect human health, the U.S. Environmental Protection Agency has established both daily (24-hour) and annual standards for PM2.5 of 35 µg/m3 and 12 µg/m3, respectively.1   

    To examine the contribution of wildfires to levels of PM2.5 in the Central Valley, Climate Central compared the number of days PM2.5 exceeded federal standards at at least one station in each air basin for the entire year, with the number of days the pollutant exceeded federal standards during the summer wildfire season from June to September. The analysis covered the period 2000 to 2016 and was conducted separately for two air basins comprising the Central Valley — the Sacramento Valley and the San Joaquin Valley. Together, these valleys cover 20,000 square miles2 and are home to nearly 6.7 million people.3

    Between 2000 and 2016, air quality in both the Sacramento Valley and the San Joaquin Valley improved, with the number of days per year with 24-hour PM2.5 exceedances falling by roughly 64 percent and 45 percent overall, respectively.  

    Amid this overall trend, a growing percentage of exceedances are occurring during peak fire season and when PM2.5 are typically low. That points to the increasing role of wildfires as a source of air pollution even as emissions from other sources continue to fall. The Sacramento Valley is now seeing some years with 50 to 60 percent of PM2.5 exceedances occurring during these months. In the earlier part of the period studied, summer exceedances typically accounted for less than 10 percent of the total. There has been a 31 percent increase in the number of exceedances during the summer fire season in the San Joaquin Valley compared to the number of exceedances during the summer fire season in 2000. The increase in proportion of summertime exceedances in the Sacramento Valley air basin has been even more dramatic with nearly a five-fold increase.

    Air quality data for the Central Valley prior to 2000 is only partially available. Data prior to 2000 was excluded based on the criterion of having less than 5 percent of the data missing. The data analyzed does not include 2017 because not all winter months have yet occurred this year. Note that winter months historically have the most exceedances.

    Because wildfire smoke can blow across county, state and national borders, the correlation between local PM2.5  and nearby wildfire activity is not exact. Comparing periods of exceedances at local levels with satellite images of smoke, however, provides another line of evidence connecting wildfires to PM2.5 pollution.

    For example, exceedances in PM2.5 concentrations were detected by air quality monitors at three locations in the Central Valley at the beginning of September 2017, with these exceedances coinciding with an outbreak of wildfires. Just a few days later, widespread smoke was still apparent in satellite images of the region, and there is a visible relationship between air quality data and the smoke. Areas where the wildfires are located and smoke is present  largely coincided with measurements showing the worst air quality.

    Major wildfires broke out north of San Francisco in early October, 2017, killing more than 40 people.4 Smoke from these North Bay fires spread throughout the San Francisco Bay Area and reached the Central Valley and beyond. Air in the Bay Area air basin is usually cleaner than in the Central Valley, and it has also experienced an overall decline in the number of days each year that PM2.5 exceeds federal standards. Smoke from the October fires heavily polluted the air, with one day in the Bay Area air basin experiencing twice the level of PM2.5 of any day going back to 2001.

    Climate Change

    Wildfire seasons are projected to become worse due to climate change, expanding in length and increasing the number of large fires and acreage that burns each year.  When compared with the 1970s, the average annual Western U.S. wildfire season is now 105 days longer, has three times as many large fires (larger than 1000 acres), and burns more than six times as many acres.5

    According to the 2014 National Climate Assessment, warming temperatures and drier conditions are major factors resulting in the increase in wildfires; both temperatures and reduced moisture are linked to human-caused climate change and affect the dryness and flammability of landscapes, measured by scientists as fuel aridity.6 High levels of fuel aridity can provide large areas conducive for the spread of wildfire once ignited.

    According to one study that looked at eight fuel aridity metrics in the Western U.S. and modeled climate change’s effects on them, human-caused climate change accounted for about 55 percent of the observed increases in fuel aridity between 1979 and 2015 (Figure 6), and added an estimated 4.2 million hectares of forest fire area between 1984 and 2015.7 Based on all eight metrics, the Western U.S. experienced an average of 9 additional days per year of high fire potential due to climate change between 2000 and 2015, a 50 percent increase from the baseline of 17 days per year when looking back to 1979. The correlation between fuel aridity and forest fire area each year was found to be highly significant (R2 = 0.75) for 1984 to 2015.

    One of the eight metrics analyzed by the study is the Keetch-Byram drought index (KBDI), a measure of the dryness of the top 8 inches of the forest floor on a scale from 0 to 800. Lower numbers on the scale indicate a higher moisture level on the forest floor and higher numbers on the scale indicate more severe drought and thus higher wildfire potential.

    Previous Climate Central research found that under a high-pollution future scenario (i.e., RCP8.5), California would experience an additional 24 days per year with a KBDI value of 600 (the level at which the potential for wildfires is high) or above by 2050.5 The only state with a greater increase in the number of days with high KBDI values is Arizona, at 34 additional days.

    Ecosystem changes and natural climatic variation can also have large influences on wildfire seasons. Even without human-caused climate change, wildfires would have increased in many regions due to other human activities and natural factors. In particular, although wildfires are a natural process in Western ecosystems, their roles in keeping forests in healthy condition have not been well understood, and so they are often extinguished as quickly as possible. As a result of strenuous efforts to suppress wildfire and other land-management practices such as livestock grazing, logging, and land-type conversion,8,9 many forests have experienced fire deficits, becoming overgrown and littered with flammable material such as leaf litter and saplings. Wildfires that break out during fire deficits can be unnaturally large and severe.10-12 In addition, the introduction of non-native species, especially invasive grasses, can have significant impacts on grassland wildfires as these plants can provide fuel for fires.13

    Wildfire Smoke and Health

    One of the greatest concerns with wildfires is their impact on air quality and associated health consequences; PM2.5  is just one of the pollutants in wildfire smoke, but its small size makes it a well-known threat to people’s health. Californians are at particular risk from wildfire-related health impacts, because the state has the largest population in the U.S. living in wildland-urban interface (inhabited areas approaching wildland areas) where there is an elevated risk of being exposed to wildfires.14 More than 11 million people, about 30 percent of the California population, live in these wildland-urban interfaces.5

    To explore specific linkages between wildfire smoke and health, Liu et al. (2016) developed the concept of “smoke-wave” days, defined as two or more days in a row with wildfire-specific PM2.5  concentrations above 20µg/m3 (the 98th quantile of wildfire-specific PM2.5 concentrations in the study area).15 In Liu et al. 2017, smoke wave days matched satellite (MODIS) records of large wildfires and the researchers found that as smoke-wave day intensity increased, respiratory admissions to hospitals increased.16 In particular, smoke-wave days with PM2.5  concentrations above 37µg/m3 (the 99.5th quantile) were associated with a 7.2 percent increase in respiratory related admissions to hospitals compared to non-smoke wave days. Cardiovascular admissions tended to be highest during the first two days of a smoke-wave and then decrease, while respiratory admissions exhibited the opposite trend, increasing as the days go by.16

    These findings are consistent with other studies, as highlighted in a critical review of the literature on the health impacts of wildfires published in 2016 by Reid et al.17 Various respiratory problems in asthmatics and non-asthmatics alike, measured by physician visits, emergency department visits, and hospitalizations were found to be strongly associated with wildfire smoke exposure as well as significant declines in lung function for those without asthma.17

    Included in the review analysis is one study that looks at how measures of community health modified health outcomes from a wildfire in North Carolina. The study found that health effects of wildfire pollution are significantly associated with poverty and income inequality.18 The study first finds that per 100µg/m3 of PM2.5 exposure, there was a 66 percent increase for hospital visits related to asthma on the day of exposure, and a 42 percent increase in visits related to congestive heart failure (CHF) the day after exposure.

    The study also finds that those counties ranked lowest on the 2010 County Health Rankings for North Carolina (a measure of overall community health based on specific determinants of community health, such as education, income, access to clinical care, diet and exercise) had significantly higher relative risks of asthma on the days of and immediately after wildfire-associated PM2.5 exposure than those counties ranked highest. Of the factors examined that combine to create the County Health Rankings, the counties ranked lowest for poverty, measured as the number of children below the poverty line, had twice the relative risk of asthma as an outcome from PM2.5 exposure than those counties ranked highest (the largest difference). Counties with the greatest income inequality had 223 percent higher risks of CHF as a health outcome from wildfire pollution.

    Wildfire smoke can travel and affect communities hundreds of miles away from its source. The North Bay Fires affected air quality in the Central Valley and satellite images show it traveled more than 500 miles over the Pacific, reaching as far south as Mexico.19 In 2015, smoke from wildfires in central Canada resulted in multiple days of exceedances of EPA standards in Maryland.20 In 2002, wildfire smoke from fires in Quebec impacted populations all along the East Coast of the United States, and a nearly 50 percent increase in hospital admissions for respiratory diagnoses for the elderly was associated with the smoke plume and concurrent PM2.5 in counties in states between New York and Washington, DC.21

    The decades of work that have gone into reducing PM2.5 through environmental regulations and technological improvements are being undermined by the West’s worsening wildfire seasons, with large wildfires being amplified by higher temperatures and drier conditions associated with human-caused climate change.


    Air quality data was acquired from the California Air Resources Board’s query tool site. For the multiyear time series the following selections were made for the Sacramento Valley and San Joaquin Valley Air Basins:  PM2.5, daily average, year-at-a-glance. The total number of exceedances, labeled on the site in red, were tallied for the yearly total exceedances. Then the number of exceedances during June, July, August, and September were tallied for peak wildfire season exceedances. The ratio of these two numbers gives the fraction of annual exceedances occurring during wildfire season. This was repeated for all available years for which >95% of the days in a year had a measurement available, which was 2000 to 2016. Linear regression fits to these data were calculated using the R Statistical Software package.22  The data for the San Francisco Bay air basin was queried in a similar manner as above, but instead of recording days above the federal standard the daily average concentrations at the highest monitoring site in the basin are reported by month through October 2017.

    About this project

    Climate Central is a nonpartisan and non-advocacy nonprofit based in New Jersey that researches and reports on the changing climate. This report was written by Research and Communications Fellow Julia Langer. Data analysis by Climate Scientist Todd Sanford, Ph.D. Additional research by Features Journalist John Upton. Graphics by Multimedia Designer Megan Martin.

    Please direct queries to

    “Breathing Fire,” a feature article about wildfire pollution written by John Upton and produced in partnership with Kaiser Health News with support from the Bill Lane Center for the American West at Stanford University, can be read on Climate Central’s website and elsewhere.

    We gratefully acknowledge John Abatzoglou (University of Idaho), Ana Rappold (EPA), and Jia Coco Liu (Yale University) for reviewing the analysis and providing helpful feedback on an earlier version of this report, and Loretta Mickley (Johns Hopkins) and Colleen Reid (University of Colorado, Boulder) for providing feedback on an earlier version of the report. 


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    10. Hessburg, P. F., Churchill, D. J., Larson, A. J., Haugo, R. D., Miller, C., Thomas, A. S., … Reeves, G. H. (2015). Restoring fire-prone Inland Pacific landscapes: seven core principles. Landscape Ecol. 30(10), 1805-1835. doi:10.1007/s10980-015-0218-0
    11. Stephens, S. L. (2005). Forest fire causes and extent on United States Forest Service lands. International Journal of Wildland Fire, 14, 213-222. doi:10.1071/WF04006
    12. Calkin, D. E., Thompson, M. P., & Finney, M. A. (2015) Negative consequences of positive feedbacks in US wildfire management. Forest Ecosystems, 2(9). doi:10.1186/s40663-015-0033-8
    13. Brooks, M. L., D’Antonio, C. M., Richardson, D. M., Grace, J. B., Keeley, J. E., DiTomaso, J. M., … Pyke, D. (2004). Effects of Invasive Alien Plants on Fire Regimes. BioScience, 54(7), 677-688. doi:10.1641/0006-3568(2004)054[0677:EOIAPO]2.0.CO;2
    14. Radeloff, V.C., Hammer, R. B., Stewart, S. I., Fried, J. S.,Holcomb, S. S., & McKeefry, J. F. (2005). The Wildland Urban Interface in the United States. Ecological Applications, 15(3), 799-805.                                      
    15. Liu, J. C., Mickley, L. J., Sulprizio, M. P., Yue, X., Peng, R. D., Dominici, F., & Bell, M. L. (2016). Future respiratory hospital admissions from wildfire smoke under climate change in the Western US. Environmental Research Letters, 11. doi:10.1088/1748-9326/11/12/124018
    16. Liu, J. C., Wilson, A., Mickley, L. J., Dominici, F., Ebisu, K., Wang, Y., … Bell, M. L. (2017). Epidemiology, 28(1), 77-85. doi:10.1097/EDE.0000000000000556        
    17. Reid, C. E. Brauer, M., Johnston, F. H., Jerrett, M. Balmes, J. R., & Elliot, C. T. (2016). Critical Review of Health Impacts of Wildfire Smoke Exposure. Environmental Health Perspectives, 124(9), 1334-1343. doi:10.1289/ehp.1409277            
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    21. Le, G. E., Breysse, P. N., McDermott, A., Eftim, S. E., Geyh, A., Berman, J. D., & Curriero, F. C. (2014). Canadian Forest Fires and the Effects of Long-Range Transboundary Air Pollution on Hospitalizations among the Elderly. ISPRS International Journal of Geo-Information, 3, 713-731. doi:10.3390/ijgi3020713
    22. R Core Team (2014). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. URL
  3. Research Report by Climate Central

    In late October 2012, Hurricane Sandy took a sharp left turn into the coasts of New Jersey and New York, leading to 157 deaths, 51 square miles of flooding in New York City alone, and an estimated $50+ billion in damage (Bloomberg 2013; Kemp and Horton 2013). The name “Sandy” was retired, but risks to coastal cities for Sandy-like flooding remain. On the five-year anniversary of the storm, Climate Central has ranked the U.S. cities most vulnerable to major coastal floods using three different metrics:

    1. The total population within the FEMA 100-year floodplain
    2. The total population within the FEMA 100-year floodplain as augmented by sea level rise projections for the year 2050
    3. The total high social vulnerability population within the same areas as group #2

    Each analysis examined coastal cities with overall populations greater than 20,000. For the first one, we tabulated “at risk” population by overlaying 2010 Census block population counts against FEMA’s 100-year coastal floodplains (Crowell et al 2013) using methods adapted from Strauss et al (2012). FEMA 100-year coastal floodplains factor in storm surge, tides, and waves, and include all areas determined to have an at least one percent annual chance of flooding. Based on locations meeting these criteria and population density, New York City ranked first, with over 245,000 people at risk, followed by Miami and then Pembroke Pines, also in South Florida.

    In our second analysis, we re-ranked cities based on which have the largest populations in the expanded areas that could be threatened in the year 2050 — due to sea level rise driven by climate change, plus nonclimatic factors such as local land subsidence. We determined these areas by using median local sea level rise projections for midcentury (Kopp et al 2014) under an unrestricted emissions scenario (“Representative Concentration Pathway 8.5”) to additively elevate the FEMA 100-year floodplain, and accordingly extend it as topography allows, following methods detailed in States at Risk: America’s Preparedness Report Card Technical Methodology. After this adjustment, New York City still had the greatest number of people on threatened land, followed by Hialeah, Florida and Miami. 36 cities in Florida placed in the top 50.

    The top five cities with the greatest increase in population on land at risk when adding on sea level projections were New York City, with a difference exceeding 181,000, plus Hialeah, Boston, Fort Lauderdale, and The Hammocks, Florida.

    The yellow, orange and red show areas at or below Sandy's peak flood elevation at The Battery.

    Finally, we also ranked coastal cities by their “high social vulnerability” population within the areas delineated by our second analysis. High social vulnerability was determined using the Social Vulnerability Index developed by the Hazards and Vulnerability Research Institute, which incorporates 29 different socioeconomic variables to evaluate the ability of communities to prepare and respond to environmental hazards such as floods. New York City, Philadelphia, Houston, Baltimore, and Miami were ranked as the top five cities with the largest high social vulnerability populations within the future FEMA 100-year floodplain — and thus face a difficult double jeopardy over time.

    Sea level rise is a key indicator and consequence of climate change.

    To learn more about coastal cities at risk visit Climate Central’s States at Risk and Risk Finder.

    Analysis by Scott Kulp, PhD and Benjamin Strauss, PhD. Dyonishia Nieves, Shari Bell, and Dan Rizza contributed to this report


    Bloomberg, Michael. 2013. "A stronger, more resilient New York." City of New York, PlaNYC Report.

    Crowell, Mark, Jonathan Westcott, Susan Phelps, Tucker Mahoney, Kevin Coulton, and Doug Bellomo. 2013. “Estimating the United States Population at Risk from Coastal Flood-Related Hazards.” In Coastal Hazards, edited by Charles W Finkl, 245–66. Springer. doi:10.1007/978-94-007-5234-4.

    Kemp, Andrew C., and Benjamin P. Horton. 2013. "Contribution of relative sea‐level rise to historical hurricane flooding in New York City." Journal of Quaternary Science 28.6: 537-541.

    Kopp, Robert E., Radley M. Horton, Christopher M. Little, Jerry X. Mitrovica, Michael Oppenheimer, D. J. Rasmussen, Benjamin H. Strauss, and Claudia Tebaldi. 2014. “Probabilistic 21st and 22nd Century Sea-Level Projections at a Global Network of Tide-Gauge Sites.” Earth’s Future 2 (8): 383–406. doi:10.1002/2014EF000239.

    Strauss, Benjamin H, Remik Ziemlinski, Jeremy L Weiss, and Jonathan T Overpeck. 2012. “Tidally Adjusted Estimates of Topographic Vulnerability to Sea Level Rise and Flooding for the Contiguous United States.” Environmental Research Letters 7 (1). IOP Publishing: 014033. doi:10.1088/1748-9326/7/1/014033.

  4. By Sam Cowie, The Guardian

    Brazil has seen more forest fires in September than in any single month since records began, and authorities have warned that 2017 could surpass the worst year on record if action is not taken soon.

    Experts say that the blazes are almost exclusively due to human activity, and they attribute the uptick to the expansion of agriculture and a reduction of oversight and surveillance. Lower than average rainfall in this year’s dry season is also an exacerbating factor.

    A volunteer works to put out a forest fire in the northern area of Brasilia's National Park, in Brasilia, Brazil, August 30, 2017.
    Credit: REUTERS/Ueslei Marcelino

    The National Institute of Space Research (INPE) has detected 106,000 fires destroying natural vegetation so far this month — the highest number in a single month since records began in 1998, said Alberto Setzer, coordinator of INPE’s fire monitoring satellite program.

    “It is fundamental to understand that these are not natural fires. They are manmade,” Setzer said.

    Fires are commonly used during Brazil’s dry period to deforest land and clear it for raising cattle or other agricultural or extraction purposes.

    The total number of blazes since 1 January was 196,000, and Seltzer expressed concern that — with the dry season continuing in Brazil’s Amazon — 2017 could surpass the worst year on record, 2004, when there were 270,000 fires.

    According to INPE, deforestation has risen continuously since 2012, when a new forest code that gave amnesty to deforesters was introduced. The last available data for 2016 showed a 29 percent rise since the previous year.

    Burning is illegal and carries heavy fines, but fire is often used to clear land for pasture or crops and hunting or results from land conflicts.

    The problem was compounded, Setzer said, by a lack of oversight and manpower to contain the blazes.

    “When there is a reduction in checks and surveillance, we see an increase in the number of fires,” he said.

    View of the devastation caused by a forest fire in front of Brasilia's National Park, in Brasilia, Brazil, September 19, 2017.
    Credit: REUTERS/Ueslei Marcelino

    The government of president Michel Temer has been heavily criticised by environmentalists for making deep cuts to the country’s environmental budget, which have affected the ability of Brazil’s environmental police to perform inspections and raids.

    In September, after a month-long battle, firefighters gave up on a fire in Tocantins state park, believed to have been lit by local fishermen and carried by strong winds during an intense dry period. An area three times the size of São Paulo was destroyed, according to local media.

    “The Temer government’s policies signal for those in the countryside that the doors are open for more deforestation and more fires,” said Cristiane Mazzetti, a Greenpeace Brazil campaigner, listing a series of measures by the Temer government including reducing protected Amazon forest areas and giving amnesty to land grabbers.

    Critics say Temer is acting at the behest of powerful ranching and mining interests inside congress. Recently, the government was highly criticized for opening up a vast Amazon reserve for international mining, a decree that was later revoked.

    The states most affected by fires this year have been in the Amazon, increasingly targeted by ranchers and miners, with the Amazon biome accounting for 49 percent of the burnings.

    The Amazonian state of Pará was the worst affected, with a 229 percent increase in fires from last year. It is home to the two hardest hit municipalities, São Félix de Xingu and Altamira, home of Brazil’s controversial Belo Monte dam project.

    Reprinted with permission from The Guardian.

  5. By Damian Carrington, The Guardian

    The sixth mass extinction of global wildlife already under way is seriously threatening the world’s food supplies, according to experts.

    Farmers evaluating traits of wheat varieties in Ethiopia.
    Credit: Biodiversity International

    “Huge proportions of the plant and animal species that form the foundation of our food supply are just as endangered [as wildlife] and are getting almost no attention,” said Ann Tutwiler, director general of Bioversity International, a research group that published a new report.

    “If there is one thing we cannot allow to become extinct, it is the species that provide the food that sustains each and every one of the seven billion people on our planet,” she said in an article for the Guardian. “This ‘agrobiodiversity’ is a precious resource that we are losing, and yet it can also help solve or mitigate many challenges the world is facing. It has a critical yet overlooked role in helping us improve global nutrition, reduce our impact on the environment and adapt to climate change.”

    Three-quarters of the world’s food today comes from just 12 crops and five animal species and this leaves supplies very vulnerable to disease and pests that can sweep through large areas of monocultures, as happened in the Irish potato famine when a million people starved to death. Reliance on only a few strains also means the world’s fast changing climate will cut yields just as the demand from a growing global population is rising.

    There are tens of thousands of wild or rarely cultivated species that could provide a richly varied range of nutritious foods, resistant to disease and tolerant of the changing environment. But the destruction of wild areas, pollution and overhunting has started a mass extinction of species on Earth. The focus to date has been on wild animals — half of which have been lost in the last 40 years — but the new report reveals that the same pressures are endangering humanity’s food supply, with at least 1,000 cultivated species already endangered.

    Tutwiler said saving the world’s agrobiodiversity is also vital in tackling the number one cause of human death and disability in the world — poor diet, which includes both too much and too little food. “We are not winning the battle against obesity and undernutrition,” she said. “Poor diets are in large part because we have very unified diets based on a narrow set of commodities and we are not consuming enough diversity.”

    The new report sets out how both governments and companies can protect, enhance and use the huge variety of little-known food crops. It highlights examples including the gac, a fiery red fruit from Vietnam, and the orange-fleshed Asupina banana. Both have extremely high levels of beta-carotene that the body converts to vitamin A and could help the many millions of people suffering deficiency of that vitamin.

    Training cows to walk in groups to extract wheat in Koka villge, Ethiopia.
    Credit: CIFOR

    Quinoa has become popular in some rich nations but only a few of the thousands of varieties native to South America are cultivated. The report shows how support has enabled farmers in Peru to grow a tough, nutritious variety that will protect them from future diseases or extreme weather.

    Mainstream crops can also benefit from diversity and earlier in 2017 in Ethiopia researchers found two varieties of durum wheat that produce excellent yields even in dry areas. Fish diversity is also very valuable, with a local Bangladeshi species now shown to be extremely nutritious.

    “Food biodiversity is full of superfoods but perhaps even more important is the fact these foods are also readily available and adapted to local farming conditions,” said Tutwiler.

    Bioversity International is working with both companies and governments to ramp up investment in agrobiodiversity. The supermarket Sainsbury’s is one, and its head of agriculture, Beth Hart, said: “The world is changing — global warming, extreme weather and volatile prices are making it harder for farmers and growers to produce the foods our customers love. Which is why we are committed to working with our suppliers, farmers and growers around the world to optimise the health benefits, address the impact and biodiversity of these products and secure a sustainable supply.”

    Pierfrancesco Sacco, Italy’s permanent representative to the UN’s Food and Agriculture Organization, said: “The latest OECD report rates Italy third lowest in the world for levels of obesity after Japan and Korea. Is it a coincidence that all three countries have long traditions of healthy diets based on local food biodiversity, short food supply chains and celebration of local varieties and dishes?”

    He said finding and cultivating a wider range of food is the key: “Unlike conserving pandas or rhinos, the more you use agrobiodiversity and the more you eat it, the better you conserve it.”

    Reprinted with permission from The Guardian.