The steep green peaks of the Sierra Madre mountains that encircle Monterrey, Mexico are one of the city’s defining features—when, that is, they can be glimpsed through the city’s ever-denser gauze of air pollution. Monterrey, one of Mexico’s principal industrial hubs and wealthiest cities on a per-capita basis, ranks as the country’s third largest metropolitan area behind Mexico City and Guadalajara. Studies show it also has the country’s worst air contamination. In 2018, Monterrey’s particulate-pollution concentrations exceeded the normal range on 204 days, according to the Integral System for Environmental Monitoring for the state of Nuevo León, where Monterrey is located. That was an improvement from 2017, when the city recorded 229 days of poor air quality, says the monitoring agency, known as SIMA. “The pollution has been a problem for many, many years in Monterrey, and isn’t a new problem,” says Armandina Valdez Cavazos, director... [Log in to read more]