Urban Issues: Canyons Up the Pollution Ante
2008

Traffic Pollution in Urban Street Canyons

publication Evidence: moderate

Author Information

Author(s): Ying Zhou, Jonathan Levy

Primary Institution: Harvard School of Public Health

Hypothesis

The same amount of emissions would have a greater population exposure in a street canyon setting.

Conclusion

Population exposure to traffic pollutants in New York’s urban street canyons can be up to 1,000 times higher than in other urban settings.

Supporting Evidence

  • Traffic pollution exposure in urban street canyons can be significantly higher than in other urban areas.
  • Pedestrians are more affected by pollution in street canyons than cyclists due to their higher numbers.
  • Cost-benefit analyses of pollution controls may not fully capture the benefits in high-density urban environments.

Takeaway

In busy city streets surrounded by tall buildings, pollution can be much worse for people than in other areas because the pollution gets trapped.

Methodology

The study focused on the intake fraction, a measure of total population exposure per unit of emissions.

Limitations

The benefits of pollution controls may have been underestimated due to not considering spatial correlations and dynamic effects of street canyons.

Participant Demographics

The study emphasizes the exposure of pedestrians and daytime office workers in midtown Manhattan.

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