The effects of ozone action day public advisories on train ridership in Chicago

Eric Welch, Xiaohua Gu, Lisa Kramer

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Ground level ozone is a criteria pollutant that is significantly affected by transportation patterns. Ozone action day advisories represent one type of voluntary ozone-abating program operating in urban areas where ozone pollution is concentrated. When forecasts predict that ground level ozone will exceed healthy levels, public advisories urge citizens to voluntarily choose public transportation as a means of eliminating automobile trips and reducing mobile emissions. To obtain credit for emission reductions spurred by voluntary programs, states must provide verifiable reduction estimates. This paper applies a fixed effects regression model to a panel of hourly Chicago Transit Authority train ridership data to evaluate the potential effects of Ozone Action Day advisories in Chicago from 2002 to 2003. Findings show that while the overall effect of ozone action days on ridership is not significant, there are statistically significant changes in hourly ridership patterns that indicate a more complex relationship between the public advisories and travel behavior.

Original languageEnglish (US)
Pages (from-to)445-458
Number of pages14
JournalTransportation Research Part D: Transport and Environment
Issue number6
StatePublished - Nov 2005
Externally publishedYes


  • Ozone
  • Public campaign
  • Transit choice
  • Voluntary policy

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Transportation
  • Environmental Science(all)


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