Alerts work! Air quality warnings and cycling

Alert programs are central to strategies to reduce pollution exposure and manage its impact. To be effective alerts have to change behavior, but evidence that they do that is sparse. Indeed the majority of published studies fail to find a significant impact of alerts on the outcome behavior that they study. Alerts particularly seek to influence energetic cardio-vascular outdoor pursuits. This study is the first to use administrative data to show that they are effective in reducing participation in such a pursuit (namely cycle use in Sydney, Australia), and to our knowledge the first to show that they are effective in changing any behavior in a non-US setting. We are careful to disentangle possible reactions to realised air quality from the ‘pure’, causal effect of the issuance of an alert. Our results suggest that when an air quality alert is issued, the amount of cycling is reduced by 14–35%, which is a substantial behavioral response. The results are robust to the inclusion of a battery of controls in various combinations, alternative estimation methods and non-linear specifications. We develop various sub-sample results, and also find evidence of alert fatigue.