As in many other big cities of the world, Mexico City has made important efforts in order to reduce air pollution. Recognizing that transportation has proved to be a major pollution source within the Mexico City Metropolitan Area (ZMCM) any strategy which aims to reduce or control atmospheric pollution has to include a transportation improvement program. The main programs to combat air pollution in the ZMCM are:
Reduce the use of private vehicles. To control the number of private cars in use at any one time the government has implemented a one day stop program called HOY NO CIRCULA (Today My Car Stops). Stopping days are randomly distributed to encourage car owners to use public transport and/or adopt car pooling. A full description of this strategy, including its advantages and disadvantages as analysed by the local government, can be found at http://www.calidad-del-aire.gob.mx/sima/ddf/hoyno/indice.html.
Control of vehicle conditions. Control of vehicle conditions. As incomplete combustion in old or poorly maintained engines is a direct cause of carbon monoxide and unburned hydrocarbon emissions, the enforcement of engine maintainance standards has been another goal of ZMCM local goverment. The major compulsory program implemented in this direction is called the 'verification program'. A full description of this strategy, including advantages and disadvantages as analysed by the local goverment can be found at http://www.calidad-del-aire.gob.mx/sima/ddf/veri/indice.html.
Change of fuels. Many reformulated fuels have already been tested in the metropolitan area but only small changes in gasoline quality have been accepted so far. This is due mainly to the fact that current engine technology, combined with the meteorological and geographic characteristics of the Mexico City area are seen as the main reasons for high levels of ozone precursor emissions (and not fuel quality).
Finally, some important successes already achieved in Mexico City have to be mentioned. Although these strategies alone will not bring air pollution under control, they are making an important contribution towards reducing it. The two major programs already working within the Mexico City Metropolitan Area are: