Review of Urban Bicyclists' Intake and Uptake of Traffic-Related Air Pollution

Abstract

Bicycling as a mode of transportation is enjoying a boost in many urban areas around the world. Although there are clear health benefits of increased physical activity while bicycling, bicyclists may experience increased inhalation of traffic-related air pollutants. Bicyclists have two to five times higher respiration rates than travelers in motorized vehicles and this difference increases with bicycle travel speed and exertion level. The main goal of this work is to review the state of knowledge regarding urban bicyclists' intake and uptake of traffic-related air pollution and to identify key knowledge gaps. This review includes not only bicyclists' exposure to air pollution concentrations but also respiration rates, intake doses (the amount of pollutant that is inhaled), and uptake doses (the amount of pollutant that is incorporated into the body). Research gaps and opportunities for future research are discussed. This is the first review to specifically address bicyclists' health risks from traffic-related air pollution and to explicitly include intake and uptake doses in addition to exposure concentrations for travelers.

Keywords:

• review
• bicycle
• pollution exposure
• inhalation
• uptake
• health

Acknowledgements

The authors thank the anonymous reviewers for their thorough comments and helpful suggestions for the paper. Alexander Bigazzi is supported by a Graduate Research Fellowship from the U.S. National Science Foundation (Grant No. DGE-1057604).

Notes

1. Traffic data are reported in a companion paper, Kaur and Nieuwenhuijsen (2009).

2. Traffic data are only used in a companion paper, McNabola et al. (2009b).

3. It should be noted that metabolic energy expenditure during bicycling is the sum of energy expenditure for baseline functions and the rate of external work (Olds, 2001). Assuming that the baseline energy expenditure is roughly equal to the RMR, the MET can be expressed as a function of external power output p as . Thus, MET values increase linearly (but not proportionally) with the external power demands of bicycling.