The Metropolitan Air Quality Study of the Environment Protection Authority of New South Wales, Australia has identified motor vehicles and industry as the major sources of air pollutants. It has also identified that peak ozone levels would need to be reduced by some 45% to achieve the recommended goal. Even greater reductions will be needed to counteract the effect of population growth. Initial analysis by the EPA indicates that strategies based on control and technological changes will, alone, not achieve the reductions in air pollution required. Strategies that target urban design and transport demand will be equally important.
In 1997, the US Environmental Protection Agency issued its "Ten-Year Air Quality and Emissions Trends" report. Carbon monoxide was down by 37 percent since 1986, lead was down by 78 percent, and particulate matter had dropped by nearly a quarter.