Air pollution has a significant impact on human health and the economy. Air quality in Sydney is usually very good by international standards. For more information about air quality in Sydney, how our ventilation systems work to manage air quality within and outside the tunnels, and what has contributed to improve vehicle emissions visit the [Air Quality Portal](https://v2.communityanalytics.com.au/rms/air-quality/#). This dataset provides standardised measures of: * Carbon Monoxide * Nitrogen dioxide * Nitrogen oxides * Ozone * Sulfur dioxide * Particles < 10μm diameter * Particles < 2.5μm diameter * BTEX * Methane * Non-Methane Hydrocarbons * THC The data captured is from 01/01/2004 - 31/12/2017 and only includes sites where RMS had access to the monitor's data. More information about the sites covered can be found in the Report and associated data files.