2014 - Research

Evaluation of Bicyclists Exposure to Traffic-Related Air Pollution along Distinct Facility Types

Key takeaway: Bicyclists’ exposure to air pollution can vary with roadway and travel characteristics, and transportation-related strategies can reduce exposure.

Results:

  • Concentrations of pollutants are generally higher on high-traffic facilities, except for high exposure on off-street paths running through industrial zones.
    • Concentrations of BTEX compounds (benzene, toluene, ethylbenzene, and xylenes) were 50-120% higher on major arterials than local roads.
    • One- to two-block detours to low-volume streets can significantly reduce exposure concentrations.
  • Weather and traffic variables are approximately related to BTEX compound exposure.
  • BTEX exposure concentrations increase 2% for every 1,000 average daily traffic (ADT).
  • Researchers suggested separated bicycle facilities, low-volume routes, and off-peak travel as strategies to reduce cyclist exposure to pollutants. Bicyclists’ respiration rates are two to five times faster than motorists, resulting in higher pollution intake. Exposure to traffic-related air pollution has been connected to elevated risk for asthma, lower lung function, higher blood pressure, and cardiac mortality.

Methods:

  • This report included a literature review of bicyclist exposure and dose measurements as well as on-road physiology and air quality data collected by three cyclists in Portland, OR over nine days. 

National Institute for Transportation and Communities. (2014). Evaluation of Bicyclists Exposure to Traffic-Related Air Pollution along Distinct Facility Types. NITC-RR-560.

Authored by: 
National Institute for Transportation and Communities