An emission budget for dioxins from crop and bush fires in Australia

Previous inventory estimates of dioxins (PCDD), furans (PCDF) and dioxin-like PCB emissions from bushfires in Australia have been limited by the small number of published estimates of emission rates. However, the situation has been improved by a recent field study that measured emission factors for PCDD, PCDF and PCBs from 20 prescribed fires, wildfires and sugar cane fires across Australia. These data are used in a revised inventory methodology that also accounts for uncertainties in inventory activity data and parameters. Incorporating these new data into an emissions budget indicates a new best estimate for Australia’s PCDD, PCDF and PCB emissions from open burning in 1994 of 142 g TEQ with an uncertainty range of 31g to 494g TEQ which is 70% lower than the previous estimate. Forest fires and crop residue burning accounted for 8% of total emissions with the remainder occurring in savanna woodlands of northern Australia. Total emission increased by 70% between 1990 and 2001 to 229 g, due entirely to increased fire activity in the savanna woodlands.