Long-term exposure to Ozone and PM2.5 in Mexican Cities of the National Urban System: a Health Impact Assessment.

Abstract

Air pollution is a process that introduces diverse pollutants into the atmosphere that cause harm to humans, several studies have documented an association between air pollution exposure and negative effects on human health. Health Impact Assessment (HIA) has been applied in many countries to quantify the impact of interventions on controlling air quality and reducing effects on human health. The National Urban System (SUN for its acronym in Spanish) aggregates the principal urban areas in Mexico where living 92.6 millions of inhabitants that represents 74.2 percent of total population. A HIA to Ozone and PM2.5 long term exposure was conducted following the method described by WHO using 2015 air pollution data. SOMO35 indicator for ozone and annual mean for PM2.5 were calculated to assess the impact in terms of the number of attributable deaths. A total of 14 SUN cities (33 millions of inhabitants) were analyzed based in ozone monitor network coverage. For PM2.5 a total of 15 SUN cities (36 millions of inhabitants) were included considering the monitoring coverage. Approximately 4 700 deaths were attributable to 35 ppm annual ozone excess, almost 50% of them (2 300) occurs in Mexico City. For PM2.5 about 11 500 deaths could have been avoided if Mexican cities had met the WHO air quality guidelines. To our knowledge this is the first study that analyze avoidable deaths using SOMO35 WHO metric as indicator of long term exposure to ozone in Mexico. This study reveal air pollution impacts in around 35% of the National Urban System and provide information for decision making.