Cyclists' exposure to air pollution under different traffic management strategies

Sci Total Environ. 2020 Jun 25:723:138043. doi: 10.1016/j.scitotenv.2020.138043. Epub 2020 Mar 20.

Abstract

We characterized the air pollution exposure of cyclists in the city center of Curitiba (Brazil) and then systematically analyzed the influence of several traffic management strategies (bus lanes, bicycle lanes, traffic calming area, traffic lights, and cleaner vehicle technologies) on the exposure. We focused on concentrations of particulates monitored on-board bicycles: PM2.5, black carbon mass (BC) and particle number concentration (PNC), and also reported on total volatile organic compound concentrations (TVOC). Overall, mean (± standard deviation) exposure was moderate compared to other cities around the world (BC: 6.98 ± 11.53 μg m--3, PM2.5: 33.22 ± 25.64 μg m-3, PNC: 3.93 × 104 ± 4.17 × 104 cm-3, TVOC: 361 ± 99 ppb). Concentrations were higher in the morning rush hour than in the afternoon traffic peak, and exhibited a large spatial variability. Bus stops and signalized traffic intersections emerged as hotspots when compared to the rest of the journey, increasing all particulate concentrations. Lower exposure was found on streets with low traffic (particularly, small number of heavy-duty vehicles) and within shallow canyon structures. The impact of traffic calming areas on cyclists' exposure is still inconclusive and further experimental and modelling studies are needed. Simple emission calculations based on traffic activity and real-world emission factors suggested that replacing the diesel bus fleet with hybrid electric buses might largely decrease (64%) the exposure to BC in the city center. Urban planners could use this valuable information to project new cycleways, which would lead to healthier active transportation. Synchronizing traffic signals might further reduce exposure at intersections.

Keywords: Bus rapid transit; Bus stop; Cycleway; Traffic calming area; Traffic light; Urban air pollution.

MeSH terms

  • Air Pollutants / analysis*
  • Air Pollution / analysis*
  • Brazil
  • Cities
  • Environmental Exposure / analysis
  • Environmental Monitoring
  • Particulate Matter / analysis
  • Vehicle Emissions / analysis

Substances

  • Air Pollutants
  • Particulate Matter
  • Vehicle Emissions