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Air quality

Some three-quarters of the population of Latin America and the Caribbean live in cities. Several megacities such as Buenos Aires, Mexico City, Rio de Janeiro and So Paulo, each with a population of more than 10 million, are located in the region and economic growth in these urban centres has caused increases in air pollution (particularly CO, NOx, SO2, tropospheric O3, hydrocarbons and SPM) and associated human health impacts (UNEP 2000). Today the problem extends beyond large cities and also affects medium-size cities and small islands (Dalal 1979, Romieu, Weitzenfeld and Finkelman 1990). The transport sector is a major source of urban air pollution - 70 per cent of emissions in Buenos Aires (PAHO 1998) and Mexico City (INEGI 1998) are transport-related, with the number of cars in Mexico City increasing fourfold between 1970 and 1996 (ECLAC 2000a). Industry, agriculture and the municipal sector also contribute to air pollution. In Santiago, the most significant sources of air pollution are transport, and small and mediumsize enterprises (IMO 1995). In addition, unfavourable topographic and meteorological conditions in some cities aggravate the impact of pollution: the Valley of Mexico obstructs the dispersal of pollutants from its metropolitan area as do the hills surrounding Santiago (ECLAC 2000b).

Air pollution increases mortality
In 1992, it was estimated that 76 million urban people were exposed to air pollutant concentrations exceeding WHO guidelines. In So Paulo and Rio de Janeiro, air pollution was estimated to be responsible for 4 000 premature deaths annually (CETESB 1992). Studies in Brazil, Chile and Mexico have shown that a 10 g/m3 increase of concentration of PM10 (particles of 10 or less in diameter) in the air coincides with a 0.6 to 1.3 per cent increase in mortality in those over the age of 65 (PAHO 1998).

The growth of industry, agriculture and transport sectors over the past 30 years has been accompanied by a steady increase in CO2 emissions - estimated at 65 per cent between 1980 and 1998 (UNEP 2001a). In 1991-92, the region was estimated to be responsible for some 11 per cent of global anthropogenic emissions of CO2 - 4.5 per cent of global industrial emissions and 48.5 per cent of emissions from landuse change (UNDP, UNEP, World Bank and WRI 1996). Deforestation is thought to be the principal cause of emissions in the region, particularly in the Amazon basin (UNEP 1999). Deforestation and livestock breeding (the latter is significant in Argentina, Chile and Uruguay) also result in a huge regional methane emission - some 9.3 per cent of the world total (UNFCCC-SBI 2000).

The average annual per capita carbon emission from industry in the region was 0.73 tonnes in 1998, somewhat lower than the world average of 1.06 tonnes (Marland, Boden and Andres 2001). Mexico is the region's largest carbon emitter.

Carbon dioxide emissions per capita: Latin America and the Caribbean (tonnes carbon per capita/year)

Average industrial carbon emission in Latin America and the Caribbean in 1998 was 0.73 tonnes/year, compared to the global average of 1.06 tonnes

Source: compiled from Marlan, Boden and Andres 2001

Industrial pollutants originate mostly from fuel combustion processes in the power generation sector, although emissions of heavy metals such as lead and mercury are also important (PAHO 1998). In oilproducing countries, emissions from the refining process are also significant - for example, in Mexico City, almost 60 per cent of SO2 emissions originate from industry, including oil refineries in the metropolitan area (INEGI 1998). In many countries, mining activities result in local deterioration of air quality (PAHO 1998).

Other sources of air pollution have local and subregional impacts, including pesticide use in agriculture and airborne particles resulting from soil erosion and biomass combustion. Studies conducted in Colombia and Ecuador in the early 1990s revealed that more than 60 per cent of agricultural workers involved in production for foreign markets had symptoms of acute pesticide poisoning (headaches, allergies, dizziness, dermatitis, blurred vision) while others experienced serious chronic effects (stillbirths, miscarriages, and respiratory and neurological problems). Neighbouring inhabitants can also be affected, as has been found for Nicaraguan cotton fields and Costa Rican coffee plantations (UNDP, UNEP, World Bank and WRI 1998, UNEP 2000).

Forest fires are another important contributor to air pollution, sometimes having a significant longdistance effect (CCAD and IUCN 1996, Nepstad and others 1997). In 1997, for example, the smoke from fires in Guatemala, Honduras and Mexico drifted across much of the southeastern United States, prompting the Texas authorities to issue a health warning to residents (UNEP 2000).

In Latin America and the Caribbean, about onefifth of the population uses biomass as a major household fuel, resulting in indoor air pollution. This mainly affects women, children and the elderly who stay indoors for long periods. In Colombia and Mexico, for example, women using biomass for cooking are up to 75 times more likely to contract chronic lung disease than the average person (UNDP, UNEP, World Bank and WRI 1998). Air pollution is blamed for 2.3 million annual cases of infantile chronic respiratory sickness and 100 000 cases of chronic adult bronchitis in the region (ECLAC 2000b).

Dealing with air pollution in Mexico City

In Mexico City, one of the biggest megacities in the world, studies have shown a close correlation between urban air pollution and the acceleration of pulmonary diseases, ageing processes in the lungs and respiratory infections (Loomis and others 1999, PAHO 1998, WHO 1999). A comprehensive programme to cope with air pollution in the Valley of Mexico was launched in 1990 aimed at improving the quality of fuel, promoting public transport, reducing emissions from vehicles, industry and services, and reforestation. The 1995-2000 Programme to Improve Air Quality in Mexico City (Proaire) introduced new activities in the field of monitoring, education and public participation. Other initiatives included the establishment of the Valley of Mexico Environmental Trust Fund, which is maintained with tax revenue from petrol and finances air quality improvement activities, the Automatic Environmental Monitoring Network, Environmental Emergency Programmes, 'A Day Without a Car' Programme, a reforestation programme and environmental education in the metropolitan area of Mexico City (ECLAC 2000a).

In recent decades, significant efforts have been made to cope with air pollution, especially in urban areas (see box) through strategies that include emission controls, changes in fuels and contingency controls. In Santiago, SPM emissions - and the number of days when alerts were sounded or emergencies declared - have been reduced considerably over the past decade, with concentrations of PM10 and PM2.5 decreasing by 24.1 per cent and 47.4 per cent respectively between 1989 and 1999 (CAPP 2000). This is largely due to implementation of a plan initiated in 1990 which included control of household and industrial emissions, developing monitoring capacity, removing highly polluting buses, controlling bus circulation and emissions, introducing car catalytic converters, improving motor fuel quality, and paving streets (ECLAC 2000c, O'Ryan and Larraguibel 2000).

Notwithstanding the progress achieved, urban air pollution is a serious concern even in some small and medium-sized cities because of the continued growth of the transport and industrial sectors, coupled with a lack of adequate monitoring and regulations. The growth of vehicles due to rising real incomes and the removal of tariffs could nullify the progress made in improving air quality. By 2010, 85 per cent of the population are expected to be living in urban areas, and combating air pollution and preventing its negative health impacts will be a priority in every country.