By Michael Gallagher, NJSAF, USFS Silas Little Experimental Forest
Prescribed burning is the primary means of managing hazardous fuel loads and reducing wildfire risk in New Jersey and many other parts of the country, however smoke emissions produced from burns have the potential to become significant health and safety hazards if not properly considered for in prescribed burn planning. This is especially important in urban or EPA designated non-attainment areas, such as the New Jersey Pinelands, where the potential exists to cause airborne pollution loads to exceed EPA regulated air quality standards and quickly cause local visibility and respiratory hazards. This is typically caused by a pollutant referred to as PM 2.5 or particulate matter 2.5 nanometers in size or smaller (a major constituent of smoke). Air quality standards and equations for estimating emissions produced during operational prescribed burns are available through the EPA, however emission calculations also require inputs of fuel consumption data and can therefore be difficult to complete.
Between 2008 and 2010, the US Forest Service’s Northern Research Station studied fuel consumption and particulate emissions in the New Jersey Pinelands. Pre-burn fuel loading and fuel consumption were estimated at a series of prescribed burns, and PM 2.5 emissions from prescribed fires between 2002 and 2008 and for the 6,300 hectare Warren Grove Wildfire of 2007. Actual PM 2.5 concentrations were also measured daily during prescribed fire season and at a prescribed fire in 2008 using special monitoring and meteorological equipment.
Results of the study suggest that seasonal air currents during prescribed burn season are typically adequate for dispersing emissions from prescribed burns, and that current prescribed burning practices are unlikely to exceed EPA standards; however short term air quality in the immediate vicinity of a prescribed burn can potentially exceed standards. Consideration of urban development in the immediate vicinity of potential burn units is therefore an important consideration for planning of burns or treatment strategy. The study also found fuel consumption in the New Jersey Pinelands to be proportional to pre-burn fuel loading, which can be estimated using modeling or biometric techniques, such as transect intercept techniques. Such estimates alone are useful for planning or comparing the effect of fuel treatments in different stands.
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