Air pollution in Sydney                                                                                                                                                                     • In the Sydney region carbon monoxide, nitrogen dioxide, sulfur dioxide and lead concentrations are consistently well below national standards. • Ambient levels of ozone and particles can exceed national standards in the Sydney region, with no definite downward trend in the concentrations of these pollutants apparent. • Total emissions of ozone precursors and particles have decreased in Sydney over the last decade despite the growth in vehicle activity, energy consumption, population and the economy. • Reductions in on-road mobile source emissions have been significant over the last decade due to improved fuel quality and more stringent vehicle emission standards. • Despite reductions in vehicle emissions, transport remains a major source of air pollution in Sydney, being the largest source of oxides of nitrogen and carbon monoxide emissions and contributing significantly to total emissions of volatile organic compounds and fine particles. • Regional modelling for Sydney has indicated that the pattern of motor vehicle emissions is a major factor determining the timing and peak of ozone concentrations in the region. • The NSW air quality monitoring network operated by the Office of Environment and Heritage (OEH) is located to meet the requirements of the National Environment Protection (Ambient Air Quality) Measure (AAQ NEPM). The purpose of the network is to measure air quality that is representative of that experienced by the general population rather than peak pollution near an industrial site or busy road.