Commercial premises can pose a threat to health and amenity at the local level, mainly through emissions of particles and VOCs. VOC sources include aerosols, surface-coating operations and solvents (the latter being a particular cause of odour complaints). Commercial food-processing operations can also place local amenity at risk because of odour emissions. As previously discussed, smoke from poorly designed and operated domestic wood heaters can pose a significant seasonal risk to amenity and health at both neighbourhood and airshed scales. Collectively, domestic and commercial sources annually contribute around one-third of VOCs to the Sydney and Melbourne airsheds, approximately one-quarter to one-third to particulate pollution in Sydney, and one-half to particulate pollution in Melbourne. In the case of Melbourne, the contribution of both VOCs and particles is concentrated in winter, because they are strongly associated with domestic heating.