How Harmful is a Fire?

By Jonathan Cruz

Brendon Haggerty crouched beside a Solo Stove fire pit in his Portland backyard and stacked a few pieces of well-cured wood. This is a common scene for many households, hanging out with friends and family around a warm, bright fire. He crumpled sheets of newsprint and lit the flame. 

Haggerty supervises the wood smoke curtailment program at the Multnomah County Health Department and illustrated the impact of fires on air quality for his friends as they gathered in his backyard. Moments after the flame was lit, the air quality monitor he was holding began to beep. As smoke from the flames blew across his backyard, the air quality shot right through the hazardous level, maxing out the device’s ability to measure air pollution. 

Haggerty’s demonstration proved what public health officials have long warned: cozy backyard fires might feel good on a cool night but even fire pits marketed as “efficient” or “smokeless” are not harmless. It’s a key reason why Multnomah County regulates indoor and outdoor fires year-round.

“Most of us probably don’t imagine that one fire could be a problem, but to a vulnerable neighbor it really could be harmful,’’ Haggerty said. “So even if that fire brings some people closer together, chances are someone lives nearby who is going to suffer the consequences.” 

The problem is that wood smoke contains fine particulate matter (PM 2.5), a dangerous pollutant for human health due to its prevalence. The particulates, smaller than the diameter of a human hair, can cause respiratory irritation, coughing, sneezing and shortness of breath. Long-term exposure to PM 2.5 may lead to preterm births in pregnant mothers, decreased lung function, bronchitis, diabetes and increased mortality from cancer and heart disease.

Why do we burn wood?

With rising costs, many assume that people burn wood to stay warm. As an affordable source of energy, especially during hard times, wood is readily available and for a good price. Yet consumer data shows that most households in Multnomah County are not building fires to stay warm, but for enjoyment.

The Oregon Department of Environmental Quality estimates that about 3,500 households in Multnomah County rely on wood as their primary source of heat, or just about two percent of the population. Comparisons of income data from the Census Bureau and burning behavior from American Community Survey underscores that most of the burning occurs in higher-income households that have other sources of heat. In particular, higher-income households in inner east Portland area burn more wood than communities in East Portland, often as a recreational or discretionary activity rather than a primary source of heat. 

Why does my fire matter?

Wood burning may seem like a personal choice, since it is often done in one’s own home or backyard. But the health impacts of smoke affect everyone in the community. 

The Environmental Protection Agency estimates that emissions from residential wood smoke account for 11 percent of cancer risk from air toxins in Multnomah County. Residential wood smoke is a significant source of human caused particulate matter in Multnomah County. Wood smoke can also reach far more people because of the sheer volume of emissions and the dense urban distribution of people across the County.

“Talking to your neighbors is the best way we can help people understand the impact of this problem,” Jonathan Cruz, a program specialist for the county’s wood smoke program, said. “It can be difficult to explain to people who burn wood that their actions are having negative consequences, but it’s worth having a conversation.”

Air quality has improved overall since the 1970’s under the Clean Air Act, but the benefits are not shared by all residents. Air quality is among many environmental justice concerns in environmental justice (EJ) communities in Multnomah County. EJ communities are low-income households and communities of color, and face environmental injustices due to historically discriminatory policies, building codes and development that concentrated these communities along high traffic corridors. Unintentionally, higher-income neighborhoods, whose air has gotten cleaner over time, may be contributing more wood smoke and worsening disparities in air quality across the County through recreational burning. 

The County is working to improve air quality for everyone and reduce these disparities by regulating wood burning and educating residents about the problem. Exemptions remain for residents with low incomes and in situations where wood burning is the primary source of someone’s heat, used for ceremonial purposes or during an emergency. Cooking food is also exempt. 

Cruz says the regulation is expected to improve conditions throughout Multnomah County and will benefit everyone affected by woodsmoke. “The good news about air pollution is that it is a solvable problem,” Cruz said. “To protect your health, check the status before you burn.” 

More information can be found at

How Harmful is a Fire?

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