Evolution of particulate matter and ozone in downtown Santiago for the period 1988–2016. The upper panel shows PM10 and PM2.5 24 hour averages collected using a dichotomous sampler as described in Barraza et al. (2017). The lower panel presents 8 hour averages of ozone for the same site. In the case of ozone, the data collected before 1997 are differentiated with respect to later data subject to more careful quality control by environmental authorities. Red and blue lines show daily air quality standards for these pollutants according to current Chilean legislation. Standards are shown only for reference. Particulate matter data were provided directly by officials of the Chilean Ministry of the Environment. Ozone data prior to 1997 were previously downloaded from the website of the Regional Secretariat from the Chilean Ministry of Health (Gallardo et al., 2012a). Ozone data for 1997 onwards are available at http://sinca.mma.gob.cl and were downloaded on January 21 2018. Here we show validated data according to the Ministry for the Environment. See Supplemental Material for details. DOI: https://doi.org/10.1525/elementa.293.f5