This research report, released in November 2011, examines the results of a project which aimed to assess the comparative risk associated with exposure to traffic pollution when travelling via different transport modes in New Zealand cities. Concentrations of the key traffic-related pollutants (particulate matter: (PM): PM10, PM2.5, PM1; ultrafine particles (UFPs) and carbon monoxide (CO)) were simultaneously monitored on pre-defined routes in Auckland and Christchurch during the morning and evening commute on people travelling by car, bus, on-road bike, train (Auckland only) and off-road bike (Christchurch only) from February to May 2009.

The key results of this research are:
• Car drivers are consistently exposed to the highest average levels of CO.
• On-road cyclists are exposed to higher levels of CO, PM1 and UFPs than off-road cyclists.
• Car drivers and bus passengers are exposed to higher average levels of UFP than cyclists.
• At some parts of their journeys, travellers are exposed to very high levels of pollution, often for short periods of time.
• Locating cycle paths just a short distance from roads can reduce pollution exposure significantly.
• One hour of commuting could contribute up to 20% of total daily CO and UFP.
• PM10 and PM2.5 are inappropriate indicators of exposure to vehicle emissions.