Santa María – a Peruvian city located to the west of the Andes mountain range – was the most polluted city in Latin America in 2024, based on fine air particulate matter concentration (PM2.5). That year, the city reported an average PM2.5 concentration of 53.4 micrograms per cubic meter. This was followed by Coyhaique, located in Chile, with an estimated PM2.5 concentration of around 40.5 μg/m³. Pollution in Latin American capitals The Chilean capital, Santiago, registered an average PM2.5 concentration of 21.3 μg/m³ in 2023. Lima, the Peruvian capital, had an estimated PM2.5 concentration of around 19.7 μg/m³, while in the capital of Mexico (Mexico City), air pollution amounted to 22.3 μg/m³. The World Health Organization's air quality standards recommend a maximum annual average concentration of 10 μg/m³. The burden of pollution on health Air particulate pollution has been associated with an increase in mortality from cardiovascular and respiratory diseases, as well as development of lung cancer. This is specially concerning considering that nearly 2.8 billion people worldwide are exposed to hazardous levels of air pollution. In particular, South Asia was home to the countries with the highest exposure to hazardous concentrations of air pollution in 2022.