Variations in exposure to traffic pollution while travelling by different modes in a low density, less congested city

This research assessed the comparative risk associated with exposure to traffic pollution when travelling via different transport modes in Christchurch, New Zealand. Concentrations of PM1, UFPs and CO were monitored on pre-defined routes during the morning and evening commute on people travelling concurrently by car, bus and bicycle. It was found that car drivers were consistently exposed to the highest levels of CO; on-road cyclists were exposed to higher levels of all pollutants than off-road cyclists; car and bus occupants were exposed to higher average levels of UFP than cyclists, and travellers were occasionally exposed to very high levels of pollution for short periods of time. PM10 and PM2.5 were found to be poor indicators of exposure to traffic pollution. Studying Christchurch adds to our understanding as it was a lower density city with limited traffic congestion compared most other cities previously studied. -- Highlights: •This paper compared commuter exposure by car, bus, and on- and off-road cyclists. •The sampling was carried out in a low density, less congested city. •As in larger cities, car occupants were exposed to the highest levels of pollution. •On-road cyclists are exposed to higher levels of pollutants than off-road cyclists. •PM10 and PM2.5 are inappropriate indicators of exposure to vehicle emissions. -- This study carried out in a low density, less congested city, found that like studies in large or densely populated urban areas car drivers are still exposed to the worst quality air