Pollution emissions impact of public transit : evidence from a long strike

Abstract

The Government of Canada will spend $20.1 billion over the next ten years, through the Budget 2017, to improve public transit infrastructure in Canada. Previous literature shows that public transit can reduce traffic congestion and consequently improve commutes and reduce air pollution. Using panel data from the Ontario Ministry of the Environment and Climate Change, I conduct a triple difference-in-difference regression to observe the impact of the 51-day OC Transpo strike in Ottawa on air pollution. Similar to previous literature, at the time of the strike during rush hour, the ambient concentration of particulate matter (PM2.5) increased by 2.02% of a standard deviation. In contrast, I find a decrease in the concentrations of nitric oxide (NO) and nitrogen oxides (NOX) by 9.6% and 6.5% of a standard deviation, respectively. These results suggest that not all public transportation is good, and that inefficient or aging infrastructure may contravene with the intended positive environmental impact of public transit.