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Cyclist route choice, traffic-related air pollution, and lung function: a scripted exposure study

Sarah Jarjour1*, Michael Jerrett1, Dane Westerdahl2, Audrey de Nazelle3, Cooper Hanning1, Laura Daly1, Jonah Lipsitt1 and John Balmes14

Author Affiliations

1 University of California, Berkeley, 50 University Hall, Berkeley, CA, 94720, USA

2 Cornell University, Ithaca, NY, USA

3 Centre for Research in Environmental Epidemiology (CREAL), Doctor Aiguader, 88, Barcelona, Spain

4 University of California, San Francisco, 1001 Potrero Ave, SFGH 30, San Francisco, CA, 94110, USA

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Environmental Health 2013, 12:14  doi:10.1186/1476-069X-12-14

Published: 7 February 2013

Abstract

Background

A travel mode shift to active transportation such as bicycling would help reduce traffic volume and related air pollution emissions as well as promote increased physical activity level. Cyclists, however, are at risk for exposure to vehicle-related air pollutants due to their proximity to vehicle traffic and elevated respiratory rates. To promote safe bicycle commuting, the City of Berkeley, California, has designated a network of residential streets as “Bicycle Boulevards.” We hypothesized that cyclist exposure to air pollution would be lower on these Bicycle Boulevards when compared to busier roads and this elevated exposure may result in reduced lung function.

Methods

We recruited 15 healthy adults to cycle on two routes – a low-traffic Bicycle Boulevard route and a high-traffic route. Each participant cycled on the low-traffic route once and the high-traffic route once. We mounted pollutant monitors and a global positioning system (GPS) on the bicycles. The monitors were all synced to GPS time so pollutant measurements could be spatially plotted. We measured lung function using spirometry before and after each bike ride.

Results

We found that fine and ultrafine particulate matter, carbon monoxide, and black carbon were all elevated on the high-traffic route compared to the low-traffic route. There were no corresponding changes in the lung function of healthy non-asthmatic study subjects. We also found that wind-speed affected pollution concentrations.

Conclusions

These results suggest that by selecting low-traffic Bicycle Boulevards instead of heavily trafficked roads, cyclists can reduce their exposure to vehicle-related air pollution. The lung function results indicate that elevated pollutant exposure may not have acute negative effects on healthy cyclists, but further research is necessary to determine long-term effects on a more diverse population. This study and broader field of research have the potential to encourage policy-makers and city planners to expand infrastructure to promote safe and healthy bicycle commuting.

Keywords:
Bicycle boulevards; Active transportation; Air pollution; Lung function