Air Pollution in Cities With Unplanned Urban Growth, a Case Study of Toluca Valley: Trends and Health Impacts Compared With Mexico City

Abstract

Abstract Unplanned urban growth is occurring in many cities around the world in developing countries and is associated with social and environmental problems such as air pollution. The case study of the Metropolitan Area of Toluca Valley (MATV) provides a clear example of disorganized urban growth and high levels of air pollution. Since 2019, the IQAir platform has ranked MATV as the city with the worst air quality in Mexico, in terms of PM2.5. Based on this scenario, ten-year (2011-2021) monitoring databases of air criteria pollutants (ACP) from six MATV monitoring stations were processed to establish seasonal and spatial distributions and to estimate the mortality proportion attributable to PM2.5 exposure. The results were compared with the evolution of ACP concentrations and the proportion of mortality attributable to PM2.5 of Mexico City. In addition, COVID-19 lockdown impact on ACP concentrations was also assessed. PM2.5 and PM10 are the main ACP that worsen air quality in MATV and exceed the WHO Air Quality Guidelines (AQG) almost the entire year risking health population. The estimated mortality proportion due to natural deaths (ICD-10) associated with PM2.5 exposure in 2019 for MATV was 11.97% (7.98-15.55) as for Mexico City, 6.95% (4.59-9.1). MATV presented higher levels of ACP and lower reduction percentages than Mexico City Metropolitan Area over the ten-year period, PM and O3 patterns are very similar between cities, suggesting that air pollution is shared. COVID-19 lockdown in 2020 showed a reduction of all ACP concentrations except for O3.