Impact of public transport strikes on traffic and pollution in the city of Barcelona.

• Metro and RENFE strikes increase air pollution. • Air pollution is slightly affected by bus strikes. • Effects on pollution are larger for public transports with no direct substitutes. • Metro and RENFE commuters switch to private cars when there is a strike. • FGC users switch to non-pollutant transports during strikes. Many Spanish cities' air contains excessive levels of pollutants caused by traffic. These pollutants are associated with high concentrations of vehicles in urban and surrounding areas, such as Madrid and Barcelona. According to the World Health Organization (WHO), 96.8% of Spain's population breathe polluted air. This paper provides empirical evidence on the effect of public transport strikes on Barcelona's air quality through an econometric analysis. The period analyzed included 147 days of some kind of public transport strike: bus (57), metro (21), trains (71), and tram (4); and also four general strikes. The estimates show that public transport strikes increases the concentration level of SO2, CO, PM 10 , and NOX throughout the city, especially in the case of metro and RENFE trains. These results also allow us to understand how commuters substitute transport modes and to propose specific policies to increase public transport use. [ABSTRACT FROM AUTHOR]