Taming Wildfires’ Far-Reaching Effects

AS CALIFORNIA RESIDENTS KNOW all too well, climate change is making for warmer and drier conditions in the Western U.S., resulting in longer, more active, and more severe wildfire seasons. The apocalyptic images of forests engulfed in flames and the human toll of lives and property lost tend to draw the most attention, but people who live farther away from the fires are also affected. Dr. Miriam Marlier, assistant professor of environmental health sciences at the UCLA Fielding School of Public Health, notes that in high-fire seasons, wildfire smoke can account for up to half of outdoor air pollution — a health threat likely to loom even larger in coming years, amid the continuing climate trends.

“Across the U.S., we have made a lot of progress over the last few decades in cleaning the air,” Marlier says. “One reason wildfires represent a growing concern is that they are contributing significantly to air pollution — not only at the wildland-urban interface, close to where the burning occurs, but in large swaths of the state downwind from the fires.”

Marlier is an environmental scientist who collaborates with experts across disciplines to study climate-related hazards, their impact on public health, and the optimal strategies for addressing them. In her research, she uses remote sensing and atmospheric modeling to determine where and when fires are occurring, their severity, and the health implications for people who experience the downwind pollution — in some cases, large distances from the fires themselves. Marlier’s modeling simulations serve several purposes: assessing the contributions of wildfire smoke, versus other pollution sources, to overall air pollution; retrospectively quantifying how fires have contributed to pollution and health effects; and allowing her team to make projections based on current and future climate conditions, as well as projecting the impact of mitigation strategies.

Marlier’s focus is on particulate matter 2.5 (PM2.5) — tiny particles in the air that have been shown by researchers at FSPH and elsewhere to cause significant health effects. “Isolating the wildfire contribution to PM2.5 suggests it might be more toxic than when we look at PM2.5 from all sources combined, which underscores the need for more research on this topic,” Marlier says. Her team also seeks to better grasp how wildfire-specific PM2.5 affects health when it interacts with other climate exposures, such as extreme heat. “It’s important to understand who is most vulnerable to these overlapping exposures — whether it’s people with preexisting conditions, young children, the elderly, pregnant women, or outdoor workers — as well as what ability these populations have to adapt, whether it’s through air conditioning, filtered air, or clean-air shelters,” Marlier explains.