When we think of air pollution, what immediately comes to mind is smoke and car exhaust fumes – outdoor pollution. But although this is dangerous, at a global level indoor pollution actually poses a far greater health risk. The latest estimate from WHO, as depicted in Figure 100, shows that indoor air pollution costs about 14 times more deaths than outdoor air pollution. Moreover, both in developing and developed urban areas, the death toll from it is far greater. In total, indoor air pollution is estimated to cost 2.8 million lives each year.

Indoor air pollution in the developing world

Indoor pollution is especially a problem in the Third World. Here, about 3.5 billion people – more than half the population of the globe – depend on traditional fuels such as firewood, charcoal, dried dung and agricultural wastes to cook and heat their homes. These fuels all develop far more soot, particles, carbon monoxide and toxic chemicals than more modern fuels such as gas and kerosene.

When particles and carbon monoxide in particular are released in large quantities in small homes, they subject the residents to far higher contamination levels than they would meet in even the most highly polluted city.