About UNEP UNEP Offices News Centre Publications Events Awards Milestones UNEP Store
GEO-3: GLOBAL ENVIRONMENT OUTLOOK  
UNEP Website GEO Home Page

Air quality

Over the past 30 years, air quality has deteriorated seriously in many urban centres and exposes millions of people to pollutant levels above the limits recommended by the World Health Organization (CEPAL 2000). Air pollution affects the health of more than 80 million inhabitants in the region and results in the annual loss of some 65 million working days. It is the main cause of almost 2.3 million cases a year of respiratory disease in children and more than 100 000 cases of chronic bronchitis in adults (CEPAL 2000).

Two factors have contributed to the increase in urban air pollution: an increase in the number of motor vehicles and an increase in travel time due to road congestion (CEPAL 2000). Motor vehicles produce 80-90 per cent of the lead in the environment, even though unleaded gasoline has been available for some time in most countries in the region (World Bank 2001). Deficient public transport as well as the separation of homes from workplaces in cities, resulting in more frequent and longer journeys, have also contributed to the increase in emissions (CEPAL 2000). The large distance between the home and the workplace stems from the absence of national urban policies combining economic, environmental and social goals. Nevertheless, the region also has some good examples of urban planning since the 1970s (see box). A combination of physical and meteorological factors associated with the location of large cities has also influenced the pollution rate (CEPAL 2000) - for example, the metropolitan area of Mexico City is located in a valley that captures pollutants causing smog.

In the past ten years, there has been substantial progress in air quality management in a number of cities. Air pollution in large cities such as Buenos Aires, Mexico City, Rio de Janeiro, São Paulo and Santiago has been reduced by means of strategies that include emission controls, changes in fuels and contingency controls. However, these programmes have not yet been extended to medium-sized cities in most of which the information needed to implement such measures is not available (ECLAC and UNEP 2001).

A model for public transport systems

The Mayor of Curitiba, Brazil, describes his city as 'a model for developed and developing countries alike'. Its urban transport system, constructed in the 1970s, encouraged residential and business development, and harmonized with the plans for the city. In 1973, the Research and Urban Planning Institute of Curitiba developed special buses designed for mass transit. Further adapted and enlarged to respond to growing population needs in the 1980s and 1990s, the system now transports two million people per day. The integrated transit network provides four alternate modes of transport, integrated within the 12 municipalities of the metropolitan region. The mass use of Curitiba's transit system has reduced the number of vehicles on the road, thereby reducing air pollution, lowering the incidence of smog and lessening the threat of respiratory illness.

Curitiba became the first city in Brazil to use a special fuel made up of 89.4 per cent diesel, 8 per cent anhydrous alcohol and 2.6 per cent soybean additive. This fuel is less polluting and cuts particle emissions by up to 43 per cent. The mixture of alcohol and soybean additive also brings social and economic benefits, maintaining employment in rural areas: every billion litres of alcohol used generates approximately 50 000 new jobs.

Source: Taniguchi 2001