page_title: Air pollution in Mexico City
section_title: Present day air pollution
hierarchical_section_title: Air pollution in Mexico City / Present day air pollution
caption_attribution_description: English: IMECA, Indice Metropolitano para la Calidad del Aire (Metropolitan Index for Air Quality), issued by the Mexico City Secretary of Environment.
context_page_description: Air Pollution in Mexico City has been a concerning issue to all citizens and members of the health departments for some time. In the 20th century, Mexico City's population rapidly increased as industrialization brought thousands of migrants from all over the world.". Such a rapid and unexpected growth led to the UN declaring Mexico City as the most polluted city in the world in 1992. This is perhaps due to Mexico City's high altitude, its oxygen levels are 25% lower and fuels do not combust completely. But it is important to mention that proliferation of vehicles, rapid industrial growth and the population boom are considered the main causes of this situation. The Mexican government has several active plans to try to reduce the emission levels that requires citizen participation, some of which include vehicular restrictions, increase of green areas and expanding bicycle accessibility.
  Air pollution causes about one in seventeen of all deaths in the country. It is the eighth largest cause of death, after factors such as diet, overweight, high blood pressure, alcohol and drugs, smoking and lack of exercise.
context_section_description: In April–May 2016, ozone and suspended matter pollution in Mexico City reached levels that were detrimental to health, though the criterion to signal a pollution alert was lower in 2016 than in the 1980s. The city's population continues to grow, to spread out, which lengthens automobile trips, and the number of autos in the city increases yearly.
  The air-quality monitor system (IMECA) is the tool used by the Mexican Authorities to measure air quality. A total of 8 system monitors, located all around Mexico City measure the levels for the 6 main pollutants that are found in the atmosphere of the city. The measured pollutants are: O3, PM10, PM2.5, CO, NO2, SO2. In addition, the stations have a meteorological tower, equipped with sensors that measure the ambient temperature, wind speed and direction, precipitation, solar radiation, relative humidity and barometric pressure.
  Indicators for each pollutant allow to assess the state of air quality, with respect to specific pollution events. Indicators of the maximum hourly concentrations and daily mobile averages were used to evaluate the behavior of the concentrations presented by the criteria pollutants and their reference to health protection standards. IMECA is the index used to display the level of pollution and the level of risk that represents to the human health in the greater Mexico City as well as the time of the measurements or the actions recommended for protection.
  To report the quality of the air, the IMECA uses 5 index categories:
  Good  — when the index is between 0 and 50 imecas. The quality of air is considered satisfactory and the air pollution poses minimal or no health risks.
  Fair  — when the index is between 51 and 100 imecas. The quality of air is acceptable, however some contaminants could have moderate health effects for a small fraction of the population that has high sensitivity to some contaminants.
  Poor  — when the index is between 101 and 150. In this value, some sensitive groups can have health effects. Some people can experience minor symptoms, including people with breathing or heart problems, children and old people. At this stage, there is no significant risk for the general public.
  Harmful — when the index is between 151 and 200. In this situation everybody can experience negative health effects. Members of sensible groups can present serious issues. This interval activates the phases precontingencia (precontingency) and contingencia fase I (1st contingency phase) of the Programa de Contingencias Ambientales Atmosféricas(PCAA) del Valle de México (Atmospheric Environmental Contingencies Program of Mexico City).
  Extremely Harmful  — when the index is more than 201. In this condition the general population may experience very serious symptoms and health effects.
caption: Imeca Scale for Air Quality
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