Pressure indicators

Fossil fuel consumption

Many human activities contribute to air pollution, but the main sources are related to energy production and consumption, especially fossil fuels (Semarnat-INE, 2005, Environment Canada et al., 2007; European Communities, 2008). Combustion of these fuels releases pollutants such as carbon monoxide, nitrogen oxides, hydrocarbons, as well as byproducts such as sulfur dioxide, all of which not only affect air quality, but lead to acid rain and changes in global climate (Environment Canada, 2008, European Communities, 2008). The indicator Country-wide final consumption of oil products indirectly measures the pressure imposed on air quality. This indicator is also used by the Canadian Ministry of the Environment (Environment Canada) and the OECD (OECD, 1998, 2002; Environment Canada, 2003).

Pollutant emissions

Air pollution results from a complex mixture of sources, from industrial smokestacks and motor vehicles to the use of cleansing products, household cleaners, paints, etc. Although climatic aspects are also major influences, generally the higher the pollutant emission levels, the higher the concentrations at which populations are exposed (WB, 1998; INE-Semarnat, 2007b). In this sense, the indicator National pollutant emissions show the direct pressure imposed on the local atmosphere, with the ensuing impairment of air quality. Data on the volume and sources of emissions are basic inputs for the development of air quality improvement programs. This indicator has been proposed in various international initiatives, although the pollutants included vary and the indicator shows nationwide figures. The UN’s and OECD’s Sustainable Development Indicators include total emissions of sulfur oxides and nitrogen oxides at the national level, whereas Environment Canada includes emissions of volatile organic compounds. OECD includes an important variation: emissions intensity (emissions per GDP and per capita; OECD, 1998, 2002; INEGI and Semarnap-INE, 2000; Environment Canada, 2008).