Stanford researchers unveil a new method to make prescribed burns safer and cleaner, reducing harmful emissions by up to 77%. Discover how these efforts are set to transform fire management and community health.
Prescribed burns have long been a vital tool in forest management, but the smoke they generate poses significant health risks. Now, researchers at Stanford University have discovered a new way to make these burns cleaner and safer, significantly reducing harmful emissions. This advancement could lead to a notable decrease in respiratory issues and cancer risks for communities near burn sites.
In a recent study published in Atmospheric Pollution Research, scientists found that by adjusting key burn parameters, emissions of carcinogenic polycyclic aromatic hydrocarbons (PAHs) can be slashed by up to 77%. The researchers estimate that this could cut cancer risks from smoke exposure by over 50%.
“There is clearly potential for improving prescribed burn procedures, such that the health impact is reduced,” lead author Karl Töpperwien, a postdoctoral fellow in the Department of Mechanical Engineering in Stanford’s School of Engineering, said in a news release. “We can essentially kill two birds with one stone – protect ecosystems while simultaneously protecting communities that would be otherwise at risk.”
The Stanford team’s breakthrough was achieved through a collaborative effort involving medical researchers from the Harvard T.H. Chan School of Public Health, physicists from the SLAC National Accelerator Laboratory and chemists from Aerodyne Research Inc. Medical researchers pinpointed the most toxic pollutants, while chemists developed methods to measure them precisely.
“They are excellent experimentalists who really advanced the frontier of measuring chemical species at high selectivity and precision,” senior author Matthias Ihme, a professor of mechanical engineering in Stanford’s School of Engineering and of photon science at SLAC National Accelerator Laboratory, said in the news release.
The researchers conducted their experiments in a lab-sized combustion chamber using Eastern White Pine samples due to their high PAH emissions. By fine-tuning the moisture content, heat intensity and oxygen levels of the fires, they demonstrated a significant reduction in PAH emissions.
First, wood moisture content was optimized at 20-30%. If the wood is too dry, it will burn too fast, generating more smoke. If the wood is too wet, it will smolder, increasing PAH emissions.
Second, the ideal heat intensity was set between 60-70 kW/m².
Lastly, the fires needed an oxygen level of 5-15% to burn most efficiently.
“There will be some limitations to upscaling this, but I clearly see a path towards making this technique more viable for a broader range of environmental conditions,” added Ihme, who is also a principal investigator at the Stanford PULSE Institute at SLAC.
Forest managers already use some of these techniques, preparing wood by chopping, drying and measuring moisture content to optimize burn efficiency. However, understanding how to precisely control oxygen and heat intensity in real-world burns will require further research.
The next steps for the research team include field experiments to replicate their lab findings and exploring the method’s applicability to different types of wood. Their goal is to balance cleaner burns with efficiency and cost-effectiveness.
“Fire is more complex than we think,” Ihme added. “It’s not only finding where the flame is, but also how the smoke is transported, how it affects long-term health, and how it is admitted into the environment as it settles from the air onto the soil.”
This research was funded by the Stanford Sustainability Accelerator, the Google Academic Research Awards program, the Moore Foundation and the U.S. Department of Energy. The project is part of Stanford’s broader effort to enhance community and ecosystem resilience against climate-related challenges.