2026-06-11 スタンフォード大学
＜関連情報＞
- https://news.stanford.edu/stories/2026/06/prescribed-fires-smoke-pollution-impact-research
- https://www.science.org/doi/10.1126/science.aea2490
- https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2025AV001682
軽度の火災による大気汚染対策 The air pollution benefits of low-severity fire
Iván Higuera-Mendieta and Marshall Burke
Science Published:11 Jun 2026
DOI:https://doi.org/10.1126/science.aea2490
Effect of fire severity on fire risk.
We used satellite-derived measures of fire severity and past fires to evaluate how low-severity fire influences future high-severity fire risk. Low-severity fire reduced subsequent fire severity in both burned areas and nearby unburned (“spillover”) areas. We estimate that a decade of large-scale (500 to 2000 km2/year) low-severity treatments across California would reduce net cumulative smoke concentrations by up to 10%.
Abstract
Wildfires are reversing decades of air quality improvements across much of the US. Expanded use of prescribed fire is a primary proposed solution, but air quality trade-offs—more initial smoke for less smoke later—remain poorly quantified. Using two decades of satellite-derived measurements of fire severity and smoke particulate matter across California, we assessed the causal effect of low-severity wildfire, a proxy for prescribed burning, on subsequent wildfire activity and air quality. We found that low-severity fire reduced the probability of very-high-severity wildfire by 92%, with reductions lasting a decade and extending 5 kilometers from treated locations. Reduced future smoke far outweighed the smoke produced during treatment, with benefit-cost ratios exceeding five after a decade. Sustained treatment of 500,000 acres annually would reduce cumulative smoke fine particulate matter (PM2.5) by about 10% after a decade.
米国西部における最近の計画的野焼きと土地管理が山火事の燃焼強度と煙の排出量に及ぼす影響 Effect of Recent Prescribed Burning and Land Management on Wildfire Burn Severity and Smoke Emissions in the Western United States
Makoto Kelp, Marshall Burke, Minghao Qiu, Iván Higuera-Mendieta, Tianjia Liu, Noah S. Diffenbaugh
AGU Advances Published: 26 June 2025
DOI:https://doi.org/10.1029/2025AV001682
Abstract
Wildfires in the western US increasingly threaten infrastructure, air quality, and public health. Prescribed (“Rx”) fire is often proposed to mitigate future wildfires, but treatments remain limited, and few studies quantify their effectiveness on recent major wildfires. We investigate the effects of Rx fire treatments on subsequent burn severity across western US ecoregions and particulate matter (PM2.5) emissions in California. Using high-resolution (30-m) satellite imagery, land management records, and fire emissions data, we employ a quasi-experimental design to compare Rx fire-treated areas with adjacent untreated areas to estimate the impacts of recent Rx fires (Fall 2018–Spring 2020) on the extreme 2020 wildfire season. We find that within 2020 wildfire burn areas where Rx fires were used prior to 2020, burn severity changed by −16% (p < 0.001) and smoke PM2.5 emissions changed by −101 kg per acre (p < 0.1). Rx fires in the wildland-urban interface (“WUI”) were less effective in reducing burn severity and smoke PM2.5 emissions than those outside the WUI. Overall, Rx fires led to a net reduction of −14% in PM2.5 emissions, including those from the Rx fires themselves. The proposed policy of treating one million acres annually in California could reduce smoke emissions by 655,000 tons over the next 5 years, equivalent to 52% of the emissions from 2020 wildfires. Our analysis provides comprehensive estimates of the net benefits of Rx fire on subsequent burn severity and smoke PM2.5 emissions in the western US, an empirical basis for evaluating proposed Rx fire expansions, and valuable constraints for future modeling.
