Environmental Impact of Public Transit: Evidence from a Long Strike in Ottawa.

This article takes advantage of an unusually long strike (51 days) in Ottawa to study the environmental impact of public transit. Overall, we find a robust significant increase in the concentration of particulate matter (PM) and ozone (O3) and a decrease in the concentration of nitrogen oxide (NO) during the strike on workdays between 7:00 a.m. and 7:00 p.m. The first two effects are probably due to an increase in car traffic during the strike, and the last one could be related to the absence of public buses with diesel engines. Interestingly, the concentration of PM and O3 decreased significantly during the last three weeks of the strike, suggesting that commuters eventually adapted to the lack of public transit by using environmentally friendly means of transportation. By only considering short strikes, previous studies may therefore overestimate the long-term environmental impact of public transit. [ABSTRACT FROM AUTHOR]