Data on pollutant emission inventories and air quality index reports for the Mexico City Metropolitan Area (ZMCM) can be found in the local authority information web page:
Historical data of air pollution at five specific parts of the city are available for ozone, carbon monoxide, sulphur dioxide, nitrogen dioxide and inhalated particles (PM10), pollution standard indexes (IMECA, Indice Metropolitano de Calidad del Aire), and lead concentration. 1996 data of polluted days above local standards.
Ozone concentration is the major atmospheric pollution problem in the ZMCM. The Mexican ozone standard (0.11 ppm) is frequently exceeded, so the reduction of this pollutant has been taken as an important indicator of improvement in air quality.