Impact of smoke from biomass burning on air quality in rural communities in southern Australia

In rural towns of southern Australia, smoke from biomass burning such as prescribed burning of forests, wildfires and stubble burning is often claimed to be the major source of air pollution. To investigate the validity of this claim, ambient measurements of PM2.5 and ozone were made in two rural locations in southern Australia between 2006 and 2008. In order to distinguish PM2.5 associated with smoke from other sources of particulate pollution, PM2.5 samples were analysed for specific smoke tracers, levoglucosan, non sea-salt potassium (nssK+) and oxalate. Monitoring was also undertaken in four homes to determine the extent to which ambient pollutants from prescribed burning penetrate indoors into houses.Monitoring clearly showed that, on occasions, air quality in rural areas is significantly affected by smoke from biomass combustion with PM2.5 showing the greatest impact. Concentrations of PM2.5 increased significantly above background levels at both sites during periods of wildfire and prescribed fire leading to exceedences of the 24-h PM2.5 Air National Environment Protection Measure (NEPM) Advisory standard. The 1-h and 4-h ozone NEPM standards were exceeded only during protracted forest wildfires. The impact of prescribed burning on the indoor air quality of residences depended on the duration of the smoke event and the ventilation rate of the houses. During short-duration events indoor air quality was determined by household activities. During events that persisted for several days, indoor air quality was determined by external conditions coupled with management of household ventilation rate.

► Impact of bushfire smoke on air quality is assessed for two Australian towns.
► PM2.5 increased significantly during fires, prescribed burns or woodheater usage.
► Chemical analysis confirmed that biomass combustion was a major source of PM2.5.
► Both primary and secondary emissions were observed during smoke plume events.
► Impact on indoor air depended on duration of smoke event and house ventilation rates.