U.S. Joint Fire Science Program


Date of this Version


Document Type



Fire Science Brief, Issue 122, November 2010


US government work.


Evidence shows that smoke from fires (wildfi re, controlled burning, and agricultural burning) is contributing signifi cantly to fine particulate matter (PM2.5) and haze in many urban and rural areas, affecting health, visibility, and ecosystems. In addition to the primary particulate matter directly emitted by fires, gaseous organic compounds are emitted that transform into “secondary” particulate matter downwind from fires, which contributes notably to PM2.5 and haze. States and tribes are required to implement programs to reduce emissions to meet the requirements of the Environmental Protection Agency’s (EPA’s) National Ambient Air Quality Standards and Regional Haze Rule, and central to any meaningful implementation plan is an understanding of which sources contribute to these pollutants. Air quality regulators must be able to correctly identify the sources so that managers can implement emission reduction strategies that will assist in the attainment of air quality standards. This project has developed new methodologies and tools for use by experts to better quantify what portion of fi ne particulates comes from fire, and of that amount, to determine how much comes from wildfire, prescribed fire, and agricultural burning. This information can then be directly used by air quality regulators to develop and implement plans to reduce PM2.5 and haze below regulated thresholds. However, information gaps remain: secondary particulate matter is not currently properly accounted for in estimates of contributions from fires and other sources, and information classifying fire type has not been integrated into emissions inventories. Several entities are currently working towards routine generation of this much needed information.