The concentration of air pollutants in São Paulo would be 75 percent greater if it were not for the city’s underground rapid transit system, according to a study by the Federal University of São Paulo. This figure was reached by comparing levels of atmospheric pollution on normal days with days when metro service is interrupted by strikes. Two stoppages of more than 24 hours, one in 2003 and the other in 2006, were used to conduct the measurements.

In the first case, the concentration of particulates rose from 41 micrograms per cubic meter on a regular day to 101.49 on the day of the strike. In the second case, it rose from 43.99 to 78.02 micrograms.

“It was to be expected, but the study confirmed the positive impact of the metro on the environment,” Simone Miraglia, the coordinator of the research study, told Tierramérica.