Masters Thesis Abstract: Woody Pattinson
Cyclist exposure to traffic pollution: Quantifying microscale variance and the impact of route choice
While the added fitness benefits of commuting by cycle are obvious, the overall health implications are less clear. It is well documented that heavy, long-term traffic pollutant exposure contributes to the development of a range of cancers and respiratory conditions. As we receive roughly 60% of our daily air pollutant intake during our commute, there is a pressing need to investigate solutions for reducing this figure. At the behavioural level, cyclists may be able to reduce their exposure by taking backstreet routes and using cycle ways where possible. At policy level, cyclists’ personal exposure could possibly be reduced by placing cycle lanes in between parked cars and footpaths or even moving lanes several metres from roads. This research investigates both of these questions and also compares cyclist exposure to other transport modes by logging real-time concentrations of carbon-monoxide (CO), particulate matter (PM10, PM2.5,PM1.0), and ultrafine particles (UFPs).
The study simultaneously measured differences between two cyclists, a bus commuter and a car commuter along a set route. One cyclist rode on a route consisting of backstreets and off-road cycle paths while the other followed the same route as the bus and car. Additionally, samples were taken by three cyclists riding in unison at different distances from the traffic flow.
Although previous research has reported reductions in microscale pedestrian exposure further away from roads, it has never been investigated for cyclists. A recent study found a 10-30% reduction for primary pollutants (NOx and CO) on backstreet routes, so there are indications that exposure can be reduced (Hertel et al. 2008). However, it is expected exposure results will be heavily dependant on wind direction and speed, especially at the microscale level.
There is a wide range of literature comparing inter-modal exposure, with the consensus being that cyclists and pedestrians are the least exposed while vehicle drivers are the highest. Two more recent studies have found the opposite (Briggs et al. 2008; O'Donoghue et al. 2007), highlighting the influence of local conditions and numerous variables such as in-vehicle ventilation settings. This research investigates inter-modal exposure and microscale variance under set conditions using exactly the same sampling strategies in two New Zealand cities, Christchurch and Auckland.
This multi-city, inter-modal and microscale approach to cyclist exposure is a world first and it is hoped to render results which will be most useful for informing planning, policy and future research.