IPCC Fourth Assessment Report: Climate Change 2007
Climate Change 2007: Working Group III: Mitigation of Climate Change

4.5.2 Air quality and pollution

The Johannesburg Plan of Implementation (UNDESA, 2002) called on all countries to develop more sustainable consumption and production patterns. Policies and measures to promote such pathways will automatically result in a reduction of GHG emissions and be useful to control air pollution (Section 11.8). Non-toxic CO2 emissions from combustion processes have no detrimental effects on a local or regional scale, whereas toxic emissions such as SO2 and particulates can have local health impacts as well as potentially wider detrimental environmental impacts.

The need for uncontaminated food and clean water to maintain general health have been recognized and addressed for a long time. However, only in recent decades has the importance of clean air to health been seriously noted (WHO, 2003). Major health problems suffered by women and children in the developing world (acute respiratory infection, chronic obstructive lung disease, cancer and pulmonary diseases) have been attributed to a lack of access to high-quality modern energy for cooking (Smith, 2002; Smith et al., 2000a; Lang et al., 2002; Bruce et al., 2000). The World Health Organisation (WHO, 2002) ranked indoor air pollution from burning solid fuels as the fourth most important health-risk factor in least developed countries where 40% of the world’s population live, and is estimated to be responsible for 2.7% of the global burden of disease (Figure 4.31). It has been estimated that half a million children and women die each year in India alone from indoor air pollution (Smith et al., 2000a). A study of indoor smoke levels conducted in Kenya revealed 24-hour average respirable particulate concentrations as high as 5526 µg/m3 compared with the EPA standards for acceptable annual levels of 50 µg/m3 (ITDG, 2003) and the EU standard for PM10 of 40 µg/m3 (European Council Directive 99/30/EC). Another comprehensive study in Zimbabwe showed that those who came from households using wood, dung or straw for cooking were more than twice as likely to have suffered from acute respiratory disease than those coming from households using LPG, natural gas or electricity (Mishra, 2003).


Figure 4.31: Indoor levels of particulate concentrations emitted from wood fuel combustion in selected developing countries

Source: Karekezi and Kithyoma, 2003.

Feasible and cost-effective solutions to poor air quality in both urban and rural areas need to be urgently identified and implemented (World Bank, 1998). Increasing access to modern energy services can help alleviate air-quality problems as well as realize a decrease in GHG emissions as greater overall efficiency is often achieved over the entire domestic energy cycle, starting from the provision of primary energy up to the eventual end-use. For instance, a shift from burning crop residues to LPG, kerosene, ethanol gel or biogas could decrease indoor air pollution by approximately 95% (Smith et al., 2000b; Sims et al, 2003b; Goldemberg et al., 2004; Larson and Yang, 2004).

Policies and measures aimed at increasing sustainability through reduction of energy use, energy-efficiency improvements, switching from the use of fossil fuels, and reducing the production of process wastes, will result in a simultaneous lowering of GHG emissions and reduced air pollution. Conversely, there are cases where measures taken to improve air quality can result in a simultaneous increase in the quantity of GHGs emitted. This is most likely to occur in those developing countries experiencing a phase of strong economic growth, but where it may not be economically feasible or desirable to move rapidly away from the use of an indigenous primary energy source such as oil or coal (Brendow, 2004).

Most regulations for air quality rely on limiting emissions of pollutants, often incorporating ambient air-quality guidelines or standards (Sloss et al., 2003). Although regulations to limit CO2 emissions could be incorporated as command and control clauses in most of the existing legislative schemes, no country has so far attempted to do so. Rather, emissions trading has emerged as the preferred method of effecting global GHG mitigation, both within and outside the auspices of the Kyoto Protocol (Sloss et al., 2003).

Ambient air-quality standards or guidelines are usually set in terms of protecting health or ecosystems. They are thus applicable only at or near ground level where acceptable concentrations of gaseous emissions such as SO2 can often be achieved through atmospheric dispersion using a tall stack as opposed to physical removal by scrubbers. Tall stacks avoid excessive ground-level concentrations of gaseous pollutants and are still in use at the majority of existing industrial installations and power plants around the world. If the use of tall stacks is precluded due to stringent limits being set for ambient SO2 concentrations mandate, then the alternative of SO2 scrubbers or other end-of-pipe removal equipment will require energy for its operation and thus divert it away from the production process. This leads to an overall decrease in cycle efficiency with a concomitant increase in CO2 emissions. Sorbent extraction or other processes necessary to support scrubber operations also have GHG emissions associated with them. This effectively amounts to trading off a potential local or regional acid rain problem against a larger global climate problem. The overall costs of damage due to unmitigated CO2 emissions have been estimated to greatly exceed those from regional acidification impacts arising from insufficient control of SO2 emissions (Chae and Hope, 2003).

Air-quality legislation needs to be approached using the principles of integrated pollution prevention and control if unexpected and unwanted climate impacts on a global scale are to be avoided (Nalbandian, 2002). Adopting a multi-parameter approach could be useful. A US proposal calls for a cap and trade scheme for the power sector, simultaneously covering SO2, NOx, mercury and CO2, which would specifically avoid conflicts with conventional regulations. Facilities would be required to optimize control strategies across all four pollutants (Burtraw and Toman, 2000). An approach developed for Mexico City showed that linear programming, applied to a database comprising emission-reduction information derived separately for air pollutants and GHGs, could provide a useful decision support tool to analyse least-cost strategies for meeting co-control targets for multiple pollutants (West et al., 2004).