Introduction

Air pollution is considered as a local and regional issue. Rapid urbanization has led to increasing emissions of air pollutants from transportat, energy production and industrial activities concentrated in these densely populated areas. This issue is receiving increasing attention, since a growing proportion of the world population lives in cities and demands a cleaner environment (Campos et al., 2008).

The World Health Organization (WHO) estimates that each year 800 000 persons die prematurely of lung cancer and cardiovascular and respiratory diseases caused by air pollution. Other adverse health effects include increased incidence of chronic malnutrition, acute respiratory infections, exacerbation of asthma, impaired pulmonary function, eye irritation and increased mortality in children under five years and vulnerable individuals (Lacasaña-Navarro et al., 1999; WB, 2003; Dockery and Pope, 2006). Poor air quality also produces significant negative effects on buildings and ecosystems. For example, the presence of sulfur dioxide and nitrogen oxides generates acid rain, which, besides damaging buildings, infiltrates into soil making it more acidic, thereby affecting plants and other living organisms (Environment Canada, 2007; EPA, 2009).

Air quality deterioration in Mexico became more evident in the late eighties, when the effects of pollution in Mexico City started to emerge (SE et al., 2003). In response, initiatives were launched for gathering information on air quality and the major factors that affect it in the largest cities of the country. In addition to climatic and geographical factors, air quality depends on the emission of pollutants into the atmosphere from sectors related to human activities (e. g., industry, transport and agriculture) and from natural sources (e. g. land devoid of vegetation and forest fires). For this reason, an essential component for the design and implementation of any program to address air-pollution is information on the major sources of air pollutants and volumes emitted by each sector (SMAGDF, 2008). In Mexico, several emission inventories were conducted for the major urban areas in the mid-nineties. Although it is convenient that inventories be updated every two years, coordination difficulties between local and federal authorities have prevented regular updates (Semarnat, 2009), except for the Mexico City Metropolitan Area (MCMA) the Toluca Metropolitan Area (ZMVT, for its acronym in Spanish), Ciudad Juarez and Salamanca, for which inventories for more than one date are available. The first national emissions inventory was published in 2006 for all the country’s states and municipalities (Semarnat-INE, 2006), although with data from 1999.

Currently, various cities and metropolitan areas monitor some of the major pollutants identified: sulfur dioxide (SO₂), carbon monoxide (CO), nitrogen dioxide (NO₂), total suspended particles (TSP), particles smaller than 10 micrometres (PM₁₀), ozone (O₃) and lead (Pb), which are known as criteria pollutants. The number of pollutants registered varies between cities, according to the cities’ own interests and concerns. Quality standards establishing the maximum concentration of each pollutant that should not be exceeded at any given time were also identified, aimed at protecting human health, including those most at risk (Semarnap-INE, 2000; INE-Semarnat, 2007a). Currently, particles smaller than 2.5 micrometres (PM_2.5) are also recorded in some cities and urban areas.

To comprehensively address air pollution issues in the Mexico City Metropolitan Area, the Integrated Air-Quality Management Program (PICCA, for its acronym in Spanish) was implemented in 1990. Subsequently, air quality improvement programs to (called Proaires) were also implemented in other major cities (MCMA, metropolitan areas of Guadalajara, Monterrey and Toluca Valley, Ciudad Juarez, Mexicali and Tijuana-Rosarito). More recently, the 2007-2012 Program to Improve Air Quality in Salamanca, the 2006-2012 Air Quality Management Program in Ciudad Juarez, the 2008-2012 Air-Quality Improvement Program in Leon, the Clean Air: 2007-2011 Program for the Toluca Valley and the 2006-2011 Air-Quality Management Program in the Puebla Metropolitan Area, (Semarnat, 2006; WWNWS-Puebla, 2006; GE.G. et al., 2007; GEM and Semarnat, 2007; GE.G. et al., 2008) have been implemented. Proaires usually include measures for the reduction and control of pollutant emissions, which are grounded on the relationship between pollutants emissions, their sources and the impact they cause on air quality and the population’s health (Semarnap-INE, 2000, SE et al., 2002).

References

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