Urban air pollution and time losses: Evidence from cyclists in London

We provide novel evidence of the immediate impact of air pollution on time delays in urban outdoor activities. We focus on ambient ozone, which is known to reduce lung capacity. We estimate its effect on cycling speed in London using several estimation strategies, and find that ozone reduces speed for concentrations above 20 ppb, which is far below the minimum threshold suggested by other studies. A 10 ppb increase in ozone concentration leads to a 0.3-0.4% reduction in cycling speed, despite that most cycling trips are short, so that exposure to ozone tends to be short. It seems plausible that ozone induces time losses of similar magnitude of other outdoor activities, such as walking.