This reduction resulted in a decrease in the average annual exposure level of urban residents to outdoor PM from 46 to 36 pg/m3 over 2000-11 (World Bank, 2015).11 Annual average concentrations remain above this level in several metropolitan areas, however, and peak concentrations still regularly exceed national air quality standards in many cities. Rio de Janeiro, among the cities with the greatest traffic congestion problems, registered the highest levels of PM10 exposure in 2010: both the highest annual mean concentration (67 pg/m3) and highest peak concentration (574 pg/m3) among monitored cities. In Sao Paulo, PM10 concentrations decreased over the 2000s, but the city faces high 03: concentration levels exceeded the national eight-hour average quality standard 257 times in 2010, or more than 70% of the year (IBGE, 2013). Estimates suggest that in the states of Sao Paulo and Rio de Janeiro alone, 135 000 people died from diseases caused by air pollution over 2006-11 (ISS, 2014).