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July 29, 2020

Taylor Creek and Klondike Fires, Rogue-Siskiyou National Forest, Oregon, 2018Kari Greer / U.S. Forest Service- Pacific Northwest Region

Forest fires are one of natures oldest land management tools. For more than 10,000 years, Indigenous people in the Pacific Northwest have harnessed the power of fire to control the threat of destructive wildfires and encourage new growth across landscapes. In recent centuries, as the number of people living in forested areas has increased and large amounts of fuel have built up over years of suppression, large seasonal wildfires are becoming more common. The impacts of these fires have been felt far and wide and not just by those directly affected by the flames.

Smoke and pollution caused by large wildfires can have severe and irreversible impacts on the health and well-being of nearby communities, as well as for people who live farther away. Mounting research shows that wildfire smoke can adversely affect populations living many miles away from the actual location of the fires. As the Northern Hemisphere moves into summer in the grips of the COVID-19 pandemic, the confluence of risks that fires present to our landscape and our public health have been brought into stark focus.

The University of Washington has a long history of leading research into the impacts of wildfires from an ecological and health perspective. We worked with two experts to answer some of the most frequently asked questions about wildfires in the Pacific Northwest, including the ways that the pandemic is increasing our communitys vulnerability to extreme wildfire events in the region.

Brian Harvey

Answers in Environmental impacts of wildfires section are provided by Brian Harvey, assistant professor, School of Environmental and Forest Sciences.Harveys research focuses on understanding forest disturbances like fires and insect outbreaks and how forest structure and function are shaped by disturbances, interactions among disturbances and climate.

Tania Busch Isaksen

Answers in Wildfire smoke and your health and the Wildfire smoke during the COVID-19 pandemic sections are provided by Tania Busch Isaksen, senior lecturer, Department of Environmental and Occupational Health Sciences and clinical associate professor, Department of Health Services. Busch Isaksens research is focused on public health outcomes associated with extreme heat and wildfire smoke exposures, risk communication methods and climate change-related public health adaptation planning and response, among other topics.

Fire is integral to our forests in the Pacific Northwestwithout it, they would look profoundly different than the forests that we know and love today. Wildfires do a lot work in our Pacific Northwest forests; removing fuel (by burning it away), recycling nutrients, creating critical opportunities for new trees to establish, and stimulating herbaceous growth that supports high wildlife diversity are all just a few of the critical ecosystem services that wildfires provide.

However, in some contexts of our modern world (e.g., when human safety and infrastructure is at risk), letting wildfires burn unabated is simply too dangerous. Prescribed fires are an effective tool in such situations, and are a relatively cost-effective way to reduce hazardous fuel buildup so that wildfires can do more of the work they performed historically in a way that is less threatening to society. With prescribed fires, we have a lot more choice as to where and when fire is applied as a management tool, and when and where smoke will be produced. Wildfires will always remain a key part of our forests, and prescribed fires do not make as much sense in forests where the natural fire regime is characterized by infrequent and severe fires. However, in dry, frequent-fire forests, prescribed fire is a key piece of the fire and forest management puzzle, especially in sensitive areas.

Recent decades have seen a marked increase in area burned in the western U.S. that has tracked warming temperatures over the same time period, and the Pacific Northwest is no exception. The year 2015 saw the greatest total area burned in recent history for Washington state, and many will remember several fires in eastern Washington burning more than 100,000 acres.

Recent years have also seen some fires larger than 10,000 acres on the west side of the Cascades, which historically included fire events on the order of several hundreds of thousands of acres. While the proportion of area that burns at high severity (e.g., killing most vegetation) hovers around 25% to 35% for most fires, more area burned means more area burned severely. A study in 2016 showed that nearly half of the increase in area burned across the western U.S. since the mid-1980s can be attributed to human-caused climate change. Coupling further climate warming with fuel amounts sufficient to carry fire, we should expect an increase in the potential for fire across the Northwest in the years ahead.

Fires are a key part of the ecology of our forests in the Pacific Northwest, and the role fire plays in shaping our forests varies across space. For example, a given patch of dry ponderosa pine forest on the east side of the Cascades historically experiences fire every few years to every few decades. These frequent fires remove fuels from the forest, keeping fire intensity and severity relatively low, and the thick bark on trees such as ponderosa pine allows these trees to survive many fires over their multi-century lifetime. Conversely, a typical patch of cold subalpine forests or moist Douglas-fir and western hemlock forests like what we see on the crest or west side of the Cascades historically experienced fire every few centuries or longer.

These infrequent fires historically burned through naturally high fuel amounts, resulting in large, severe fires (i.e., they killed nearly 100% of above-ground plants). This sounds scary from our human perspective, but the ecological opportunities created by these severe fires lead to extraordinarily high biodiversity for plants and animals in the decades that follow including the key natural establishment opportunity for trees like Douglas fir and lodgepole pine.

Wildfires always have been, and always will be a key part of our forests in the Northwest. That said, minimizing the number of unplanned human-caused fires is important for safely and effectively managing forests and fires. It is important to minimize sources of ignition as much as possible during the warm and dry conditions that define our fire season in the Northwest (generally mid-spring to mid-fall), and especially so when winds are high. Potential sources of ignition include: driving vehicles or operating machinery in areas with dry grass fuels; campfires and barbeques; fireworks; burning yard waste; or anything that could produce a spark or ignite highly flammable vegetation when it is warm and dry. Add high winds and that spark can escape quickly.

Adhering to local restrictions on burning is key to preventing wildfires. Around homes and structures, we can mitigate the potential for ignition by removing fuels and creating a defensible space. Several programs such as Firewise USA and the WA Fire Adapted Communities Learning Network provide useful resources that a wide range of sectors can draw upon to keep our communities safe from wildfires. We will never be able to completely prevent wildfires from occurring (and given their importance for our forest ecosystems, we may not want to), but by being careful and proactive about reducing fuels and minimizing ignitions, we can reduce the aspects of wildfires that are most dangerous to our communities.

Reversing the old adage, its safe to say, where theres fire, theres smoke. That is, given that fires are an integral part of how our forests function in the Northwest, there has always been, and always will be some level of smoke that impacts our region. But just as fire knows no boundaries and can travel from one parcel of land to another, smoke is even more mobile. For example, much of the smoke in the sky in the Pacific Northwest over the past few summers has traveled from areas as far away as northern British Columbia and California. Conversely, the smoke produced from fires in Washington can impact us directly, but can also travel far away. Because much of western North America is composed of fire-prone ecosystems, smoke is likely an inevitable consequence of living here. However, we can do a lot more to adapt in our communities to the reality of smoke, and be prepared to protect ourselves when the smoke returns.

No, all wildfire smoke is not the same. The particles and chemical constituents within smoke vary depending on the fuel burned, moisture content of the fuel and surrounding meteorological conditions. In general, ultra-fine particulate matter is the primary public-health related hazard associated with short-term and cumulative exposure to wildfire smoke. However, other hazardous air pollutants that affect health can be present in wildfire smoke.

Our understanding of the health effects attributed to wildfire smoke exposure has grown over the past several years, with widespread smoke events becoming more frequent in densely populated areas. Fine and ultra-fine particulate matter found in wildfire smoke is a respiratory irritant that can exacerbate pre-existing conditions like asthma and chronic obstructive pulmonary disease (COPD). Short-term exposure to wildfire smoke (e.g. days to weeks) has been associated with an increase in respiratory-related hospitalizations in studies across the United States. Specific to Washington State, a 2017 study led by Colorado State University looked at wildfire smoke exposure during the summer of 2012 and found an increase in asthma, COPD and all-respiratory hospitalizations during wildfire smoke events. Short-term exposure to wildfire smoke has also been linked to an increase in mortality. In Washington State, a University of Washington study in 2020 observed an increase in non-traumatic, respiratory and COPD-related mortality on wildfire smoke days compared to non-smoke days.

As with many environmental exposures, those most at risk of poor health outcomes include the elderly, young, immunocompromised, and those with underlying health conditions such as asthma, COPD and cerebrovascular disease. Specific to wildfire smoke, those who work outdoors or who are experiencing homelessness are also at greater risk because of the increased likelihood of exposure.

Good quality, frequently updated information is important when making personal decisions about how to reduce your exposure during a wildfire smoke event. Nationally, the Environmental Protection Agency (EPA) maintains the AirNow website that draws from air pollution data from multiple agencies to produce an Air Quality Index (AQI). The EPA has also created a citizen science project using a mobile app named Smoke Sense. This app provides updated AQI and active wildfire information based on your location and also encourages you to track and share your own wildfire smoke symptoms via the app in the name of science.

In Washington State, the Departments of Ecology and Health, in collaboration with local and tribal health authorities, maintain and update the Washington Smoke Information Blog. The blog helps you prepare for fire season, provides information on how to become smoke ready, displays current and forecasted air quality information, and suggests useful tips for reducing your exposure to wildfire smoke.

We also recommend you consult your local county and/or tribal health departments and regional clean air agencies, as many of these local resources have specific local interventions available during wildfire smoke events.

There are a number of actions you and your family can do to reduce your risk of health effects associated with wildfire smoke exposure. As with an emergency or disaster, preparation is key!

For individuals with COVID-19, exposure to wildfire smoke may worsen symptoms of COVID-19 or make it difficult for the bodys immune system to fight the SARS-CoV-2 virus. For those who are COVID-19 free, exposure to wildfire smoke can irritate the lungs and affect immune function, thereby increasing susceptibility to developing COVID-19 if exposed to the virus.

In pre-pandemic times, community clean air shelters were identified and used in areas impacted by wildfire smoke. These centers provided a respite to those seeking cleaner air. However, this community-level intervention is not realistic during a pandemic where social distancing is a priority. Therefore, the best way to reduce your own risk from wildfire smoke is to focus on what you can do to improve your own indoor air environment. The other major way COVID-19 has significantly impacted our normal response to wildfire smoke exposure has been to the general availability of N95 masks. Long seen as the minimum respiratory protection needed to protect from particulate matter, N95 masks are largely reserved for health care workers, as they also filter out the SARS-CoV-2 virus. Unlike with the SARS-CoV-2 virus, however, cloth masks do little to filter particulate matter from wildfire smoke.

Agencies that are well practiced in putting out wildfires are now learning a new skill: how to set the spark and fan the flames. Thats the case for the state Department of Natural Resources, which is starting to use prescribed burning as part of its strategy for fighting wildfires. Read more

A University of Washington study, published January 2020, takes a big-picture look at what climate change could mean for wildfires in the Northwest. Read more

People of all ages face a slightly increased risk of dying during and just after exposure to wildfire smoke, and middle-aged adults with underlying respiratory conditions face even greater risk, according to a new study led by the University of Washington Department of Environmental & Occupational Health Sciences. Read more

In the first major study following the devastating Carlton Complex fire, researchers from the University of Washington and U.S. Forest Service found that previous tree thinning and prescribed burns helped forests survive the fire. Read more

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Expert FAQ: Wildfires in the Pacific Northwest during the COVID-19 pandemic - UW News