UrbanAir
Pollution in
Megacities of the World by Asim Khan The freshness of the air in one's environment has amost fundamental
and direct impact on the quality and length of one's life. Imaginethis scene and you have in your mind the current state of affairs in MexicoCity, a city whose air was recently ranked by the World Health Organization(WHO) as the most contaminated in the world. In 1974 the Global Environment Monitoring System (GEMS) wascreated by the World Health Organization and The United Nations EnvironmentProgramme (UNEP) to monitor air
pollution in large cities of the world. Of foremost concern in monitoring air quality in largecities is the health and well-being of urban residents. The concentration ofambient air pollutants in many of the cities are high enough to cause increasedmortality, disease prevalence, deficits in pulmonary function andcardiovascular and neurobehavioral effects. The most recent WHO/UNEP report on air quality in 1992focused on 20 of the 24
megacities of the world. The study of air pollutionproblems in the 20 megacities is intended to guide efforts to so lve andprevent some of these problems from occurring in emerging megacities. The first observation made by the report is that airpollution is widespread across the megacities and is often most severe incities in developing countries. The worst group of the megacities in terms ofair pollution consists of Beijing, Cairo, Jakarta, Los Angeles, Mexico City,Moscow and Sao Paulo. The suspended particulate concentration of the air has asignificant impact on one's health. These are the three most developedmegacities in the world. Bus drivers have the highest prevalence of chronicrespiratory problems in the Philippines in the Pacific Rim. For the cities surveyed, high levels of lead were recordedin the air of Cairo and Karachi and, to a lesser extent, in Bangkok, Jakarta,Manila and Mexico city. Lead is now banned in petrol in countries like the US,Japan, and Sweden. In most EU countries the permissible amount of lead inpetrol is highly limited. Motor vehicle traffic is a major source of air pollution inthe megacities. In half of them it is the single most important source. In theabsence of controls, the automotive emissions will likewise increase. Theexperience of the current megacities in the developed countries is now beingrepeated in the developing cou ntries. Pro motion of the use of mass transitand finding alternatives to open burning of refuse provide some otheropportunities for reducing air pollution in the near term In the longer term, preventivemeasures must be incorporated in new industrial and urban developments.Based onthe study, WHO/UNEP (1992) made several recommendations for developingcountries to follow to address the problems of urbanization and air pollution:1) Airquality management should be implemented urgently. Such efforts are needed inwell over half of the megacities studied 2) More attention should be given to short-term, realistic approaches to beginto reduce some of the air pollution. Steps which can be taken include energyconservation, institution of motor vehicle inspection programs and phasing outlead in petrol. Pro motion of the use of mass transit and finding alternativesto open burning of refuse provide some other opportunities for reducing airpollution in the near term 3) In the longer term, preventive measures must be incorporated in newindustrial and urban developments. Proper urban and transportation planning canachieve significant improvements in air quality, as can the introduction ofclean modern technology.