The poor air quality in the Mexican capital points to the urgent need for regulations on the use of clean fuel and the control of motor vehicle emissions, warned a non-governmental organization. "The increase in concentrations of PM10 particulates (10 micrometers or less in diameter) has combined with an increase in PM2.5 particulates, which are one of the most harmful pollutants for human health, and one of their main sources is diesel engine vehicles that run on fuel with a high sulfur content," Gustavo Alanis, general director of the Mexican Environmental Law Center, told Tierramérica.

These particulates are produced by the burning of fossil fuels and pose serious health risks.

Air pollution is responsible for 38,000 deaths from lung cancer, cardiopulmonary disease and respiratory infections in Mexico annually, according to the Fourth Almanac of Air Quality Data and Trends in 20 Mexican Cities (2000-2009), published by the National Institute of Ecology.