Bushfire smoke has the potential to affect millions of people and is therefore a major public health problem. The air pollutant that increases most significantly as a result of bushfire smoke is particulate matter (PM). During bushfire smoke episodes, PM concentrations are usually much higher than urban background concentrations, at which effects on respiratory health have been observed. The smoke can cover large areas including major cities and even small increases in the risk of respiratory health effects can cause large public health problems. The association between respiratory morbidity and exposure to bushfire smoke is consistent with the associations found with urban air pollution. Although using different methods, all studies looking at Emergency Department presentations in relation to a bushfire smoke event have found associations and most studies have also found an association with hospital admissions. However, only a few studies have distinguished between the effects of bushfire PM(10) (particles with a median aerodynamic diameter less than 10 µm) and background PM(10). These studies suggest that PM(10) from bushfire smoke is at least as toxic as urban PM(10), but more research is needed.