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Wildfire smoke alters immune cells, promoting inflammation

Bill GabbertOctober 31, 2022Uncategorizedfirefighter health, public health, research, smoke, smoke & health21 Comments

Smoke Beaver Fire — Smoke at the Beaver Fire in Northern California, August 12, 2014. Photo by Bill Gabbert.

Immune cells that normally protect against inflammation and infections can be altered by wildfire smoke to promote inflammation. A long list of diseases are associated with inflammation. Studies have shown that healthy individuals and those with pre-existing conditions are affected by the very small PM2.5 particles produced by wildfire smoke.

forecast 4 a.m. PDT October 26 fire wildfire smoke — Forecast for the distribution of smoke at 4 a.m. PDT October 26, 2019 in the San Francisco area and south as far as Santa Maria.

Below are excerpts from an article written by Tori Rodriguez first published in Pulmonology Advisor. It covers the effects of smoke on humans and suggests what could be done to mitigate the potential damage. One idea is for fire and local officials when considering evacuation guidelines to plan for not only the dangers of flames, but also the effects of smoke.

[With wildfires increasing] and the health issues that result, there is a real and growing need for clinicians to educate at-risk patients, according to Jennifer Stowell, PhD, a postdoctoral researcher in the department of environmental health at the Boston University School of Public Health and co-author of a recent study on the health effects of wildfires.² “For clinicians, education of patients is paramount, especially for those with already compromised health,” said Dr Stowell.

Healthy individuals may also experience health consequences from wildfires, according to Angela Haczku, MD, PhD, professor of medicine at the University of California, Davis, School of Medicine and director of the UC Davis Lung Center. “During the 2020 California wildfire season, my team conducted a study on healthy individuals and found alarmingly increased numbers of abnormal, activated immune cells in the peripheral blood.³ These cells are normally responsible for protecting against inflammation and infections, but when altered by inhalation of wildfire smoke, they become the ones promoting inflammation,” she explained.

Research exposes burning issues

The vast majority of recent US wildfires have been concentrated in western states, including Washington (218 fires), California (153 fires), Montana (141 fires), and Utah (130 fires).¹Estimates show that more than 70,000 wildfires have burned an average of 7 million acres in the US annually since the year 2000.⁴

In addition to this geographic damage, a sizeable body of research has detailed the negative human health effects resulting from exposure to wildfire smoke:

In a study published in June 2022, Heaney et al found that “smoke event” days — those with the highest amounts of particulate matter 2.5 (PM2.5) from wildfires — were linked to increases in unscheduled hospital visits in California for all respiratory diseases (3.3%; 95% CI, 0.4%-6.3%) as well as asthma specifically (10.3%; 95% CI, 2.3%-19.0%), with the largest effect observed among children ages 0 to 5 years with asthma.²

Stratified analyses demonstrated increased visits for all cardiovascular diseases, ischemic heart disease, and heart failure among non‐Hispanic White patients and individuals older than 65 years. The findings further suggested that the interaction between wildfire PM2.5 concentrations and high temperatures may further increase the need for hospital visits among patients with cardiovascular disease.

A 2022 scoping review found evidence of increased population-level mortality, respiratory morbidity, and rates of various types of cancer in association with exposure to PM2.5 and chemicals from wildfire smoke.⁵

Findings from a 2021 study indicate that particulate matter from wildfire smoke has a greater effect on respiratory health than particulate matter from other sources of emission, based on a comparison of the increase in respiratory hospitalizations associated with increases in wildfire-specific PM2.5 (increase in hospitalizations ranging from 1.3% to 10%) and non-wildfire PM2.5 (increase in hospitalizations from 0.67% to 1.3%) in Southern California.⁶

Research published in 2021 showed that a 10 µg/m³ increase in wildfire PM2.5 was correlated with increased hospitalizations for all respiratory diseases, asthma, chronic obstructive pulmonary disease (COPD), and ischemic heart disease in Colorado. Wildfire PM2.5 was also associated with an increase in deaths due to asthma and myocardial infarction.⁷

Other results reported in 2021 linked wildfire PM.2.5 exposure in Alaska to elevated odds of asthma-related emergency department (ED) visits among various population, with odds ratios ranging from 1.10 (95% CI, 1.05-1.15) to 1.16 (95% CI, 1.09-1.23).⁸

A 2018 study analyzed data pertaining to 21,353 inpatient hospitalizations, 25,922 ED presentations, and 297,698 outpatient visits during periods of heightened smoke exposure from the 2007 San Diego wildfires. The results demonstrated a 34% increase in ED visits for respiratory diagnoses and a 112% increase in ED visits for asthma. Even greater increases in ED visits were observed among children aged 0 to 4 years with respiratory diagnoses (73% increase) and in children aged 0 to 1 year with asthma (243% increase).⁹

Studies have also demonstrated increases in ED visits and hospitalization rates for asthma and other respiratory diseases in relation to wildfire PM2.5 in states such as Oregon and Nevada.^10,11

Additionally, findings from multiple studies point to a potential connection between wildfire smoke exposure and higher rates of COVID-19 infection and associated mortality. In 1 study, researchers found that COVID-19 cases and related deaths increased by 56.9% and 148.2%, respectively, after the onset of the California wildfires that began in September 2020 compared with the period of time from the onset of the pandemic to just before the wildfires began.¹²

Results of another recent study suggest that “wildfire smoke inhalation sequesters activated, pro-inflammatory [natural killer] cells to the affected tissue compartments and may interfere with [COVID-19] vaccine effectiveness,” according to the authors.¹³

We interviewed Drs Stowell and Haczku to find out more about what clinicians need to know about the health effects of wildfires. Notably, Dr Haczku recently chaired the 2022 third annual NorCal Symposium on Climate, Health, and Equity.

“The size of the particulate matter is important….Particles larger than 10 micrometers in diameter are deposited in the nose, mouth, and upper airways, while PM2.5 is sucked directly down to the alveoli…causing disruption and inflammation.”
Dr Angela Haczku, Director of the University of California Davis Lung Center and chair of the 2022 NorCal Symposium on Climate, Health, and Equity.

What is known about the health effects of exposure to wildfire smoke?

Dr Stowell: Several studies have investigated the health effects of wildfire smoke and have linked smoke exposure to respiratory disease, cardiovascular disease, and birth outcomes such as preterm birth and low birth weight.¹⁴ Several gaps remain, including a better understanding of indoor air quality during wildfire events, the risk to outdoor workers, pregnancy complications, and mental health.

Dr Haczku: Wildfire smoke contains particulate matter of varying sizes, usually classified into PM10 and PM2.5 and ozone (O3) and nitrogen-containing toxic gases. All of these are combined with volatile organic chemicals that fuel the flames, the quality and quantity of which depend on whether what is burning comes from wild land, urban areas, or combined areas.

The size of the particulate matter is important because it determines where in the respiratory tract it will end. Particles larger than 10 micrometers in diameter (PM10) are deposited in the nose, mouth, and upper airways, while PM2.5 is sucked directly down to the alveoli, the tiny sacs responsible for our breathing, causing disruption and inflammation.

These particles are also carriers of inflammatory, allergenic, infectious, and toxic molecules causing both acute and chronic illnesses.

The most affected and best-studied organs susceptible to wildfire smoke are the respiratory tract and the cardiovascular system. Most ED visits are related to exacerbations of asthma and COPD and heart conditions such as coronary disease. Respiratory and cardiovascular mortality and hospitalization rates are well-known to be increased during wildfires. Affected adults and children also often suffer from anxiety and other mental health conditions. These conditions and the long-term health effects of wildfires are less studied and poorly understood.

What are the implications of these effects for health care systems?

Dr Stowell: Increasing wildfire activity due to climate change will continue to exacerbate these issues. Wildfire smoke exposure used to be thought of as an issue for the western US. However, as seen in the past several years, smoke from large fires and complex fires can reach across the continental US, exposing many individuals to harmful pollutants. Even with this wider spread of smoke, exposure will continue to have the greatest effect on the health of communities close in proximity to the fires, where smoke density is the heaviest.

Often the communities most affected are rural and face distance barriers to accessing proper health care. Thus, the health care systems in these already underserved areas could face capacity and response issues as wildfire smoke exposure continues to increase in western US states.

Dr Haczku: The effect of wildfire smoke on respiratory, cardiovascular, mental, and general health could be alleviated through specific interventions. As such, wildfire-related disasters provide health care systems with an opportunity to take a proactive role. Health care professionals should strategically and intentionally prepare for wildfire smoke events. Educational material should be prepared using professional society-approved guidelines and toolkits. These also need to be translated into the languages of and distributed to patients and potentially affected communities as well as the general public.

Having an efficient local system in place for timely warnings to reduce time spent outdoors during wildfire smoke events is crucial. Preventive measures in schools and indoor public places such as improved air filtration systems should be installed.

What are recommendations or considerations for clinicians to keep in mind when caring for patients in areas most affected by wildfires?

Dr Stowell: Education of patients is paramount. Some other steps could include considering temporary staff increases during wildfire seasons, ensuring the clinic staff are well-educated regarding wildfire smoke safety measures, and partnering with communities to provide clean air options for their patients.

Dr Haczku: In addition to intensive management of risk factors and chronic diseases, I believe implementing preventive measures are the most important. For example, professionals need to make sure that timely public warnings of smoke events are in place. Clinicians and health care workers should have a database that can be used to identify and reach out to vulnerable populations including pregnant women, children, the elderly, and farm and construction workers. Education of these communities and individuals can prevent emergency situations. Susceptible patients suffering from chronic illnesses and workers who cannot avoid outdoor activities may require help with fitting personal respirators and devices and specific consultation by health care workers.

What broader measures are needed to buffer the effects of wildfire smoke exposure and protect vulnerable populations, such as those with respiratory and cardiovascular diseases?

Dr Stowell: Much more needs to be done to plan for these large fire events. This planning includes focusing efforts in the areas most often affected by smoke through increasing health care system capacity, forming mobile health response teams, proper community education, better guidelines for evacuation (as most evacuations are intended to avoid the flames and not the smoke). Another need is access to clean air options, such as providing clean air centers and affordable access to air purification technology, including air conditioning and HEPA filtration.

Dr Haczku: As a health care educator, administrator, and climate change researcher, I see an urgent unmet need for the education of health care professionals about the effects of wildfires and, more generally, of climate change on human health. Vulnerable subjects, especially patients suffering from chronic health conditions, should be identified and educated. Improving advocacy toolkits and updating evidence-based professional guidelines for disease management and preventive interventions to reduce risk and protect health is imperative.

Research efforts to study and better understand wildfire smoke-induced pathologies as well as research to investigate the effectiveness of novel interventions should be better supported.

References

Fire, Weather, and Avalanche Center. Current wildfires burning in the U.S. Accessed September 11, 2022.
Heaney A, Stowell JD, Liu JC, Basu R, Marlier M, Kinney P. Impacts of fine particulate matter from wildfire smoke on respiratory and cardiovascular health in California. Geohealth. 2022;6(6):e2021GH000578. doi:10.1029/2021GH000578
Teuber M, Flayer C, Linderholm A, et al. Wildfire smoke exposure activates circulating innate immune cells. J Allergy Clin Immunol. 2021;147(2);Suppl_AB237. doi:10.1016/j.jaci.2020.12.012
Congressional Research Service. Wildfire Statistics. Updated September 2, 2022. Accessed September 30, 2022.
Grant E, Runkle JD. Long-term health effects of wildfire exposure: A scoping review. J Climate Change Health. 2022;6:100110. doi:10.1016/j.joclim.2021.100110.
Aguilera R, Corringham T, Gershunov A, Benmarhnia T. Wildfire smoke impacts respiratory health more than fine particles from other sources: observational evidence from Southern California. Nat Commun. 2021;12(1):1493. doi:10.1038/s41467-021-21708-0
Magzamen S, Gan RW, Liu J, et al. Differential cardiopulmonary health impacts of local and long-range transport of wildfire smoke. Geohealth. 2021;5(3):e2020GH000330. doi:10.1029/2020GH000330
Hahn MB, Kuiper G, O’Dell K, Fischer EV, Magzamen S. Wildfire smoke is associated with an increased risk of cardiorespiratory emergency department visits in Alaska. Geohealth. 2021;5(5):e2020GH000349. doi:10.1029/2020GH000349
Hutchinson JA, Vargo J, Milet M, et al. The San Diego 2007 wildfires and Medi-Cal emergency department presentations, inpatient hospitalizations, and outpatient visits: An observational study of smoke exposure periods and a bidirectional case-crossover analysis. PLoS Med. 2018;15(7):e1002601. doi:10.1371/journal.pmed.1002601
Gan RW, Liu J, Ford B, et al. The association between wildfire smoke exposure and asthma-specific medical care utilization in Oregon during the 2013 wildfire season. J Expo Sci Environ Epidemiol. 2020;30(4):618-628. doi:10.1038/s41370-020-0210-x
Kiser D, Metcalf WJ, Elhanan G, et al. Particulate matter and emergency visits for asthma: a time-series study of their association in the presence and absence of wildfire smoke in Reno, Nevada, 2013-2018. Environ Health. 2020;19(1):92. doi:10.1186/s12940-020-00646-2
Meo SA, Abukhalaf AA, Alomar AA, Alessa OM, Sami W, Klonoff DC. Effect of environmental pollutants PM-2.5, carbon monoxide, and ozone on the incidence and mortality of SARS-COV-2 infection in ten wildfire affected counties in California. Sci Total Environ. 2021;757:143948. doi:10.1016/j.scitotenv.2020.143948
Sanghar GK, Ravindran R, Teuber MJ, et al. Phenotypic evaluation of natural killer (NK) cells in response to BNT162b2 mRNA Covid-19 vaccine during wildfire smoke exposure. Presented at: the American Thoracic Society (ATS) 2022 International Conference; May 13-18, 2022; San Francisco, CA. Abstract A5407. doi:10.1164/ajrccm-conference.2022.205.1_MeetingAbstracts.A5047
Evans J, Bansal A, Schoenaker DAJM, Cherbuin N, Peek MJ, Davis DL. Birth outcomes, health, and health care needs of childbearing women following wildfire disasters: An integrative, state-of-the-science review. Environ Health Perspect. 2022;130(8):86001. doi:10.1289/EHP10544

Wildfires degrade public health across the country

BillOctober 19, 2022Uncategorizedfirefighter health, public health, smoke, smoke & health8 Comments

South Moccasin Fire in Montana, October, 2021. Photo by Lauren Kokinda, BLM.

By Matt Vasilogambros

As wildfires continue to burn in parts of the United States, state public health officials and experts are increasingly concerned about residents’ chronic exposure to toxin-filled smoke.

This year has seen the most wildfires of the past decade, with more than 56,000 fires burning nearly 7 million acres nationwide, according to the National Interagency Fire Center. While the total area burned is less than in some recent years, heavy smoke has still blanketed countless communities throughout the country.

Climate change is causing more frequent and severe wildfires, harming Americans’ health, pointed out Dr. Lisa Patel, deputy executive director at the Medical Society Consortium on Climate and Health, which raises awareness about the health effects of climate change.

“The data we have is very scary,” she said. “We are living through a natural experiment right now — we’ve never had fires this frequently.”

Patel sees the effects of wildfires in her work as a practicing pediatrician at Stanford Medicine Children’s Health, treating more women and underweight and premature infants at the neonatal intensive care unit when wildfires rage in Northern California.

As researchers focus on the public health impact of wildfire smoke, state health and environmental officials across the country have had to issue more air quality notices and provide guidance and shelter for residents struggling during periods of heavy wildfire smoke. And as experts have found, this issue isn’t isolated to the West Coast — it hurts more residents in the Eastern U.S.

Studies show that chronic exposure to wildfire smoke can cause asthma and pneumonia, and increase the risk for lung cancer, stroke, heart failure and sudden death. The very old and very young are most vulnerable. Particulates in wildfire smoke are 10 times as harmful to children’s respiratory health as other air pollutants, according to a study in Pediatrics last year.

What concerns experts is particulate matter in the air smaller than 2.5 microns across; there are around 25,000 microns in an inch. People inhale these microscopic bits, which then can embed deep in their lungs, irritating the lining and inflaming tissue. The particles are small enough to get into a person’s bloodstream, which can lead to other short- and long-term health effects.

Forecast for wildfire smoke at 12:01 a.m. PDT Sept. 1, 2021.

Particulates in wildfire smoke are even hindering national progress on reducing air pollution, after decades of improvement.

The federal Clean Air Act has substantially decreased the level of toxic particles from industrial and automotive pollution across the country since 1970, the U.S. Environmental Protection Agency notes. But air pollution is expected to worsen in parts of the West because of wildfires, some researchers have found. A United Nations report earlier this year warned of a “global wildfire crisis,” saying the probability of catastrophic wildfires could increase 57% by the end of the century.

Researchers are trying to better understand how more frequent wildfires affect human biology.

Keith Bein, associate professional researcher at the University of California, Davis, created a rapid response mobile research unit in 2017 that he deploys when there are fires around the state. He’s like a storm chaser but for wildfires.

With his mobile unit, Bein can measure particulate matter in the air, take samples back to his lab and then determine their toxicology and chemical compositions. When near these fires, he said, the smoke is so bad that it feels like there’s no escaping it.

“The smoke rolls in, and you get that sinking feeling all over again,” he said.

Massive wildfires that tear through communities are becoming more common. The fires aren’t just burning trees but also synthetic materials in homes. And with repeated exposure to different particulates, health risks are more pronounced and can evolve into chronic conditions, Bein said.

Researchers are just beginning to understand how more frequent wildfires in residential areas impact human health, he added.

“It’s happening more frequently every summer,” he said. “The length of the fires is growing. The public exposure to the smoke is also growing. Once-in-a-lifetime events are happening every summer. This is a different kind of exposure.”

In 2020, a study in Environment International found that winter influenza seasons in Montana were four to five times worse after bad wildfire seasons, which typically last from July until September. The findings shocked study lead author Erin Landguth, an associate professor at the University of Montana.

“We know that hospitalizations for asthma and other respiratory conditions spike within days or weeks of wildfires,” she said. “The thought that this could potentially lead to effects later and how that can affect our immune system is really scary.”

Landguth is currently expanding her study to all Western states. She expects to find a similar trend throughout the Mountain West and Pacific Northwest. Monsoon season in Arizona and New Mexico may disrupt the trend there, she said, while air pollution is already so bad in California from smog and other pollutants that it might be difficult to pinpoint how wildfires are harming human health.

But wildfires are not just in the West, nor is their health impact geographically isolated. Some fires burn so intensely at such high temperatures that smoke rises into the atmosphere, where strong winds can carry the smoke long distances.

This was glaringly apparent in 2021 when the sun glowed red, and the sky hazed over New York City and throughout the Northeast, as smoke drifted from massive wildfires in California, Oregon and other Western states.

Shot from Colorado National Monument August 7, 2020 about 15 miles Southwest of the Pine Gulch Fire. The view is looking towards the northeast and shows some of the explosive activity on the northern front Friday and the huge smoke plume extending to the east. Photo by Jennifer Deering.

That smoke is hurting the health of more people in the Eastern U.S. than it is in the West, said Katelyn O’Dell, a postdoctoral research scientist at George Washington University, who released that finding in a study in GeoHealth in 2021. Wildfire smoke contributed to more asthma-related deaths and hospital visits in Eastern communities than those in the West, she and other researchers found, in part because of higher population density.

The smoke hitting the Eastern U.S. doesn’t just come from the West; there are wildfires and prescribed burns throughout the country, said O’Dell.

“It’s sometimes easy to feel distant from fires and their impacts when you’re far from the flames of these large Western wildfires that are in the news,” she said. “But wildfires impact the health of the U.S.”

The next orange sunset people enjoy should be a moment to check an air quality mobile app, she said.

In Minnesota, the state has issued 46 air quality alerts since 2015, according to the state’s Pollution Control Agency. Of those, 34 were due to wildfire smoke, and 26 of those were issued last year.

That took state officials by surprise, said Kathy Norlien, a research scientist at the Minnesota Department of Health. The wildfire smoke risk is not just coming from the plumes that drift from the West Coast and Canada, but also from wildfires in the Boundary Waters — a lake-filled region in the northern stretches of the state. She expects the problem to worsen in the coming years.

“At this point, we’re planning for the worst-case scenario,” she said. “We have not had the extent that the Western states have had. But with climate change and concern over drought and the dry conditions, planning is of the utmost importance.”

She meets regularly with the Minnesota Pollution Control Agency and other state officials about how to get the message to state residents about the increasing wildfire risk to public health, encouraging residents to sign up for air quality alerts. State officials also have established larger community centers and buildings as safe air shelters.

The public plays an enormous role in both preventing (nearly 90% of wildfires are caused by humans, according to U.S. governmental data) and adapting to wildfires, many experts say.

For people living in fire-prone areas, there are nonflammable building materials for new homes and indoor air purifiers and upgraded HVAC systems. But these solutions may be too costly for some families, said Patel, of Stanford Medicine.

She counsels families about how to affordably stay safe during wildfire season, encouraging the use of N95 and KN95 masks, which were pivotal in combating the spread of the coronavirus. She also shares designs for do-it-yourself air filtration systems.

But she emphasized that wildfires will continue to rage across the country and cause adverse health effects unless climate change is reined in through serious public policy. Until then, climate change will continue to be the biggest threat to public health, she said.

“Summer used to be a time I’d look forward to,” she said, “but now I look at it with dread with the heat and wildfires.”

First published by Pew Charitable Trusts on Stateline. Used with permission.