Over the past several wildfire seasons, parts of the West Coast in the United States have been inundated with heavy wildfire smoke from nearby fires. This September, the trend came to a head. For several days, air quality in Portland and Seattle ranked worst among major cities in the world, with Portland’s air quality index topping 300—above which air is considered so hazardous that even nonsensitive and less vulnerable people are at risk of serious health effects. Due to the critical role of both climate change and federal land management policies in contributing to this problem, the federal government must play a key role in finding solutions.
Wildfire smoke carries very small particulates, known as PM2.5, and a variety of other gases that are hazardous to humans. While more research is needed to understand the health consequences due specifically to wildfire smoke, the effects of PM2.5 on human health are already well-understood. Fine PM2.5 particles can enter the respiratory tract and exacerbate preexisting medical conditions like asthma and heart disease. Long-term exposure to PM2.5 may lead to respiratory conditions like bronchitis and reduced lung function; exposure also has been linked to reduced cognitive functioning and even dementia. Evidence shows that communities with histories of exposure to PM2.5 tend to suffer higher mortality rates.
Nationally, exposure to PM2.5 has declined by about 40 percent since 2000. This decline is due in part to the success of the Clean Air Act (CAA), which establishes county-level air quality standards and requires areas to develop plans to improve air quality if those areas fail to meet the standards. But while the CAA has been successful in reducing industrial and automobile emissions, it expressly avoids dealing with wildfire smoke emissions. In fact, the CAA classifies wildfires as “exceptional events,” which do not count toward bringing an area into noncompliance.
This policy may not have posed problems for air quality in an era when extreme wildfire smoke events were indeed “exceptional”—but that era likely is behind us. Wildfire smoke now is a significant source of PM2.5, not just in California and the western United States, but across the nation, as well. According to a recent working paper from the National Bureau of Economic Research, up to half of all PM2.5 exposure in recent years across the western United States is attributable to wildfire smoke. Even outside the most fire-afflicted US regions, the proportion of PM2.5 exposure attributable to wildfire smoke typically reaches 10–20 percent.
Given the intensity of recent smoke events, and what we know about the harmful consequences of PM2.5, it is clear that policymakers need to address the increasing negative health impacts of wildfire smoke. One option would be to remove the CAA’s exception for wildfire smoke, as RFF Senior Fellow Alan Krupnick has discussed in a previous blog post. But this approach places the burden of reducing air pollution from fires on the states, and many western wildfires take place on federal land. In 2019, about 72 percent of the area burned in the western United States was on federal land.
Therefore, mitigating wildfire smoke will require federal involvement. Two of the primary causes of worsening wildfires can be addressed most effectively at the federal level: climate change, which has resulted in longer fire seasons and drier fuels, and land management practices, which have resulted in an accumulation of flammable vegetation in some parts of the western United States. In the short run, the federal government can commit to helping western communities adapt to the increasingly heavy burden of wildfire smoke. For example, the federal government could provide funds for improved air filtration in schools and other public buildings, along with subsidies for household indoor air filters within heavily affected areas.
In the medium term, more careful management of federal forests and wildlands over the next several decades can help mitigate wildfire smoke by reducing the heavy fuel loads that have accumulated in some areas, which in turn prompt more intense and smokier fires. Because prescribed fires and managed wildfires are key tools for reducing fuel loads, this strategy may in some cases require tolerating up-front low or moderate levels of smoke. However, forest management is not a one-size-fits-all solution for western wildlands. In fact, a departure from historic fuel conditions is not a primary factor that drives increased wildfire activity in all parts of the western United States. In areas where fuels are not the problem, reducing wildfire activity will be difficult if climate change continues unabated. Therefore, in the longer run, climate policy is critical, as well.
While state and local governments certainly can take steps to mitigate the smoke impacts of worsening western wildfires, the federal government must lead the charge. If not, wildfire smoke will threaten the health and quality of life in the western United States—and in other regions of the country—for years to come.