Increased traffic, unmitigated, will lead to increased air pollution (see Chapter 3: Atmosphere, Section 3.3.2). As well, higher household demand for energy due to population growth, and higher industrial consumption of energy associated with increased economic growth drives increased use of fossil fuel energy. This can also lead to increases in pollution unless mitigated in some way, such as by reducing the level of harmful particles emitted from particular energy sources through scrubbing, improving energy efficiency or switching to energy sources that are 'cleaner'. Some renewable energy sources such as solar are nonpolluting. Within nonrenewable sources, the use of natural gas generates less harmful pollutants than the equivalent use of coal or oil.
Although national trends are difficult to establish because of limited comparable data across cities over time, it appears that there has been a slight increase in air pollution in Australia in recent years, as measured by the number of days in which average PM10 concentration exceeded the National Environment Protection Measure standard (see Section 2.1.4). This suggests that recent mitigation measures have not been sufficient to fully offset the pressures from increased vehicular use associated with increasing population and economic growth.