UPHE opposes the US Forest Service’s “fuels reduction” strategies
“Thinning forests to protect from wildfire smoke makes no more sense than thinning your brain to protect you from Alzheimer’s.” -Dr. Brian Moench, UPHE President
Utah Physicians for a Healthy Environment (UPHE) is an organization of health care professionals concerned about the adverse impacts of environmental degradation on public health. We became concerned about the human health consequences of smoke from intentional, or “prescribed” and “slash pile” burns, when supporters showed us pictures and videos of what state and federal agencies are doing in the Wasatch Mountains. We are not forest ecologists. However, in the era of an accelerating climate crisis and an obvious global wildfire epidemic, how forests are managed has become a major public health issue, and for that reason we were compelled to investigate the issue and to take a position. And as with medical research, we strive to align that position with the best science and the opinions of the most trustworthy experts.
2025 Rebuttals to Forest Service Webinars
The Forest Service has been hosting a webinar series explaining their forest management techniques. Feeling that the webinar series was omitting important information and studies on how their practices could be harming public health, UPHE collaborated on the John Muir Project’s rebuttals.
Direct public health consequences
Live trees are pollution sponges whether in a forest or urban setting. They sequester particulate pollution, absorb ozone, carbon monoxide, nitrogen oxides, and ultrafine particulate pollution through the same stomata they absorb CO2. When those trees are lost, so is their ability to absorb pollution.
Burning “slash piles” of thinned trees and branches, as the USFS and BLM are doing throughout the West, is an assault on public health. For multiple reasons wood smoke is the most toxic type of air pollution the average person ever inhales, whether it comes from a fireplace, wood stove, a wildfire, or a prescribed burn. VOCs emitted from wood combustion are more reactive than VOCs from industrial emissions.
Although research is somewhat conflicting, compared to flaming combustion, smoldering combustion, i.e. from lower temperature, higher moisture fuel, typical for prescribed burns and slash pile burning, emits more PM2.5 per unit of fuel consumed.
The EPA calculates that, nationwide, almost as much total PM2.5 is generated by prescribed burns as from wildfires. In fact, in the Southeastern US, prescribed burns are responsible for much more PM2.5 than wildfires. We have seen no research to support the assumption that landscape scale prescribed burns reduce the total amount of biomass smoke pollution the public is subjected to. In fact, most research shows the opposite for two reasons. 1. Prescribed burns are largely ineffective in stopping high intensity wildland fires and therefore prescribed burns only add more pollution to the public’s exposure (see above section). 2. In general, lower intensity burns with incomplete combustion, like prescribed burns, are more toxic, including producing more dioxins, than an equal amount of biomass burned at higher intensity.
↓ UPHE collaborated with independent forest experts on our position on forest thinning. For our full commentary on the climate, forest health, wildfire mitigation, and public health consequences of the US Forest Service’s strategy on forest thinning, click below.↓
On a broad scale the Forest Service’s strategy is not effective in reducing massive wildfires. In fact, it is often counter-productive. Three of the main contributors to the epidemic of Western US wildfires are increased temperature, drought, and wind. Those three factors are primarily climate related and forest thinning increases all three on a local level, but also exacerbates the climate crisis globally by ending carbon absorption and sequestration of the trees and shrubs cut down, while immediately releasing their carbon when they are burned. Generally forests most resistant to those three wildfire factors are forests that have been left alone, and allowed to grow dark and dense. A large body of Independent research contradicts Forest Service dogma that our forests are unhealthy because they are plagued by overgrowth.
During the massive wildfires of primary concern to everyone, climate factors overwhelm human interventions. Under extreme wildfire conditions, wind can blow embers miles ahead of any fire front and jump over, around, or through a prescribed burn site.
It typically takes only 2-3 years for the flammable biomass on a site to return to or exceed the amount of fuel before a prescribed burn. Even less in areas with more rainfall. So unless forest thinning and prescribed burns are done with unrealistic frequency, they are only effective for a short time. However, these actions open the door for invasive cheat grass, which is highly flammable, to dominate the forest floor
As little as 1% of wildfires encounter an area that has been thinned or subject to prescribed burns. So the probability of efficacy for any one project is very low.
There is no credible evidence for the assumption that “slash pile” or “prescribed” burns result in reducing the overall volume of smoke the public would otherwise inhale. To the contrary, it means the public is exposed not only to summer time wildfire smoke, but also spring and fall wildfire smoke. The EPA calculates that, nationwide, almost as much total PM2.5 is generated by prescribed burns as from wildfires.
Hardening strategies for individual homes do help protect structures in the wild/urban interface. But thinning the forest miles away from structures only increases wildfire risk.
Resources on fire management:
Logging in disguise: How forest thinning is making wildfires worse – Grist