Tag: smoke & health

By Luke Montrose, Assistant Professor of Community and Environmental Health, Boise State University

(This article first appeared at The Conversation)

As summer approaches, two forces of nature are on a collision course, and wildland firefighters will be caught in the middle.

New research suggests that the smoke firefighters breathe on the front lines of wildfires is putting them at greater risk from the new coronavirus, with potentially lethal effects.

At the same time, firefighting conditions make precautions such as social distancing and hand-washing difficult, increasing the chance that, once the virus enters a fire camp, it could quickly spread.

As an environmental toxicologist, I have spent the last decade expanding our understanding of how wood smoke exposure impacts human health. Much of my current research is focused on protecting the long-term health of wildland firefighters and the communities they serve.

‘Camp crud’ and the dangers of air pollution

People have long understood that the air they breathe can impact their health, dating back more than 2,000 years to Hippocrates in his treatise on Air, Water, and Places. Today, there is a growing consensus among researchers that air pollution, specifically the very fine particles called PM2.5, influences risk of respiratory illness. These particles are a tiny fraction of the width of a hair and can travel deep into the lungs.

Italian scientists reported in 2014 that air pollutants can increase the viral load in the lungs and reduce the ability of specialized cells called macrophages to clear out viral invaders.

Researchers in Montana later connected that effect to wood smoke. They found that animals exposed to wood smoke 24 hours before being exposed to a pathogen ended up with more pathogen in their lungs. The researchers showed that wood smoke exposure decreased the macrophages’ ability to combat respiratory infection.

Now, new evidence suggests that long-term exposure to PM2.5 air pollution, which is produced by sources such as wildfires, power plants and vehicles, may make coronavirus particularly deadly.

Researchers from the Harvard T.H. Chan School of Public Health conducted a nationwide study of county-level data and found that even a small increase in the amount of PM2.5 from one U.S. county to the next was associated with a large increase in the death rate from COVID-19. While small increases in PM2.5 also raise the risk of death from other causes for older adults, the magnitude of the increase for COVID-19 was about 20 times greater. The results were released last week, before the usual peer review process was conducted, to help warn people of the risks.

Taken together, these findings suggest that air pollution, including wood smoke, could increase the risk that wildland firefighters will develop severe COVID-19 symptoms.

That probably doesn’t surprise seasoned firefighters.

They’re already familiar with “camp crud,” a combined upper and lower respiratory illness accompanied by cough and fatigue that has become common in firefighting camps.

The National Wildfire Coordinating Group, in its guidance on infectious disease, has pointed out that “the close, overlapping living conditions of an incident command post lends itself to rapid spreading of contagious microorganisms, as witnessed by the common outbreaks of ‘camp crud.’ Outbreaks also have a history of spreading from incident to incident as people are reassigned.”

How to protect wildland firefighters

So, what can be done to avoid the spread of COVID-19 among wildland firefighters and prevent them from being vectors in the communities they serve?

In some areas, officials have been delaying firefighter training sessions and brush-clearing operations that would normally be underway now. But while that might protect firefighters from exposure right now, it can be put off for only so long. Wildfires have already broken out in several states, and delaying controlled burns leaves more fuel when fires get out of control.

The National Wildfire Coordinating Group’s guidance on infectious disease encourages planning ahead so personal protective equipment is available and maintaining records of symptoms so illnesses can be tracked and stopped from spreading.

The guidance also calls for better camp hygiene, providing access to medical care, making isolation possible and coordinating cross-agency communication about the public health risks.

Firefighter camps are not typically well outfitted to promote good personal hygiene. Improving those conditions could help prevent a virus’s spread, such as by adding hand-washing stations and possibly mobile shower units. Single-person tents would allow for more effective social distancing.

Camp personnel should also have access to thermometers and coronavirus test kits. Protocols for quarantining and removing infected firefighters from the field should not only be implemented but practiced.

Also missing from the National Wildfire Coordinating Group’s guidance are policies on traveling to and from training sites, working within communities and traveling from camp. Social distancing may not always be possible, so protective gear, such as face masks, should be made available and their use encouraged.

A recent paper from Belgium suggests that even some of the ways firefighters operate in the field should be reconsidered to protect against the virus’s spread. It shows how droplets released when a person exhales can travel farther than six feet during heavy activity. For firefighters, that could mean walking farther apart and in a V-shaped delta formation, rather than a traditional line, to reach the fire.

It is also important to consider that frontline firefighters are often younger and could be asymptomatic but still able to spread the virus, so their contact with with rural community members, such as volunteer firefighters and ranchers, should be considered.

Finally, a system for cross-state communication should be engaged to facilitate sharing of best practices and lessons learned. It also could help track the movement of firefighters across the region.

The safety of rural western communities depends on the wildland firefighters and their ability to respond to emergencies. Protecting their health helps protect public health, too.

Researchers studying the effects of smoke on children found prescribed fire smoke to be less harmful than smoke from wildfires. The Stanford University study looked at three groups of children:

• Those who were exposed to smoke from a prescribed fire;
• Children exposed to smoke from a wildfire in which no structures burned; and,
• Children that were not exposed to smoke.

Sometimes fire personnel refer to a prescribed fire as “good fire”. Now they may call smoke from a planned burn as “good smoke”. A way to look at this research is that removing hazardous fuels near a community is a way to reduce the threat of a wildfire spreading into the town and burning structures or entrapping and killing people. And, removing the fuels with good fire rather than allowing a wildfire to burn the same area, exposes residents to less harmful smoke. For fire-prone areas, it is not IF it burns, it’s WHEN. Do you want your smoke now under controlled conditions or later, possibly under extreme conditions?

From Stanford University:

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…The study was published May 30 in the European Journal of Allergy and Clinical Immunology. It was conducted in Fresno, California, a city with high air pollution levels due to its topography and other sources, including traffic and agriculture.

“This study suggests that exposure to wildfire smoke is detrimental above and beyond poor air quality,” said the lead author, Mary Prunicki, MD, PhD, an instructor of medicine.

The study’s senior author is Kari Nadeau, MD, PhD, professor of medicine and of pediatrics and director of the Sean N. Parker Center for Allergy & Asthma Research at Stanford.

Native Americans traditionally used controlled burns to manage California’s forests, but throughout the early 20thcentury, wildfires were widely suppressed. This began to change in the 1960s and 1970s, when scientists recognized fire as a normal part of forest ecology. Recent wildfires have brought more attention to the possible benefits of prescribed burns as a way to reduce fuel levels and wildfire risk, but not everyone is enthusiastic.

Opposition to controlled burns
“We know that there’s some public opposition to doing prescribed burning,” Prunicki said. “It’s our feeling that prescribed burning, because it’s so controlled, may expose people to fewer health effects than wildfires.” Prescribed burns are of lower intensity and are permitted only when weather conditions allow the fire to be contained.

In the study, the researchers compared blood samples from three groups of children, all of whom were 7 or 8 years old. One group of 32 children had been exposed to smoke from a 553-acre prescribed burn that occurred in March 2015; a second group of 36 children had been exposed to smoke from a 415-acre wildfire in September 2015. Both fires were about 70 miles away from Fresno, and blood samples were collected from the children within three months of each fire.

The study also included blood samples from a control group of 18 children who lived in the San Francisco Bay Area and had not been exposed to wildfire or prescribed-burn smoke.

The researchers measured air pollution levels recorded at four monitoring stations in Fresno and estimated pollution levels at the children’s homes during the fires based on how far they lived from the stations.

Pollutant exposures were higher in the wildfire group compared to the prescribed-burn group.  The air pollutants measured included nitrogen dioxide, polycyclic aromatic hydrocarbons, elemental carbon, carbon monoxide and particulate matter.

Wildfire smoke exposure was associated with lower blood levels of type-1 T helper cells, a group of immune cells that are involved in the immune response. Among children exposed to wildfire smoke, the researchers also saw increased methylation of the Foxp3 gene, indicating reduced activity of this gene, which is broadly involved in modulating allergic and other immune responses. The finding of greater Foxp3 methylation is congruent with earlier studies of the effects of air pollution on the immune system, Prunicki noted.

Significance of particulate matter
One important aspect of the study was that the September 2015 wildfire was confined to forested areas and did not burn any structures.

“Particulate matter from wildfires is different from region to region and depends on what is burning,” Prunicki said. “When a wildfire is going through a town, there are a lot of concerns about what happens to the chemicals in people’s homes and cars when they go up in flames.” Smoke from wildfires that burn inhabited areas almost certainly has worse health effects than those found in the current study, she said.

The researchers plan to conduct larger, more detailed studies of the effects of wildfire smoke on health. They will be enrolling healthy people in a trial at Stanford later this summer to collect baseline data from blood samples. When future wildfires affect Bay Area air quality, the participants will be asked to provide follow-up blood samples.

The scientists also plan to research the health effects of using home air purifiers during wildfires, as well as measure the protection offered by N95 masks, with the aim of developing recommendations for when masks should be used by different populations, such as healthy adults, elderly people, children and people with chronic illnesses.

The study’s other Stanford co-authors are biostatistician Justin Lee; life science researcher Xiaoying Zhou, PhD; Francois Haddad, MD, clinical associate professor of medicine; and Joseph Wu, MD, PhD, professor of medicine and of radiology.