The urban fringe and some of the new coastal areas are notable regions of low income in Australian cities. Prevalence of asthma in children may be up to 30 per cent and appears to have doubled in the last decade. Asthma mortality is highest in rural settlements. Environmental factors such as outdoor and indoor air pollutants, grass pollens and certain foods and preservatives have been implicated in triggering attacks. Sydney's population increased by 31 per cent between 1970 and 1990 along with an increase in consumption and waste generation per head.
Motor vehicles are the dominant source of air wastes in most Australian cities.
The energy sector is the largest contributor to greenhouse gas emissions in Australia. Within this sector, motor vehicles contribute 18 per cent which is close to twice that of industry, making them the single largest end-use source of greenhouse gases. The level of gases from photochemical smog have decreased per head, although nitrogen oxides increased by 20 per cent in total. Between 1970 and 1990, Australia's average consumption of primary energy increased by 37 per cent per head. In 1992, the residential sector accounted for 12 per cent of Australia's total energy use.