It is impossible to cut fine particle emissions to WHO limits without switching away from fossil fuels
Air quality legislation will fail to keep fine particle pollution within World Health Organisation limits, unless combined with a shift away from fossil fuels and uptake of cleaner cooking stoves in developing countries, a new study concludes.
Although pollution control is improving in OECD countries, around 80% of the world’s population are exposed to concentrations of fine particles smaller than 2.5 microns (PM2.5) well above the recommended limit of 10 micrograms per cubic metre (μg/m<sup>3</sup>). Emissions are increasing, due to growing vehicle use in developing countries, plus an increase in the population dependent on traditional solid fuels for cooking and heating.
Over 2 billion people, mainly in Asia and sub-Saharan Africa, rely on burning coal, wood, dung or crop waste in smoky open fires or inefficient stoves, causing serious pollution both outdoors and indoors. There are significant health impacts, especially for women and children who spend a long time indoors in badly ventilated houses, close to stoves and fires. In this context, biomass is not a climate-friendly fuel because it is often gathered from unsustainable sources, leading to deforestation. The black carbon in the smoke is also a greenhouse gas, as well as increasing melting of snow and ice through darkening the surface so that it absorbs more heat (the albedo effect).
Scientists at IIASA modelled five future scenarios with different policies on air quality, climate change and access to cleaner cooking fuels and stoves (such as gas, biogas, LPG or efficient biomass stoves). They found that if air quality legislation was frozen at 2005 levels (scenario a), pollution would increase by 50% by 2030. Even under current and planned air quality legislation (scenario b), global average fine particle concentrations will increase by 30%, from 26 μg/m<sup>3</sup> in 2005 to 34 μg/m<sup>3</sup> in 2030, well above the recommended limit of 10 μg/m<sup>3</sup>.
But emissions of sulphur dioxide, nitrogen oxides and fine particles could be 40% lower than this under a scenario combining planned air quality legislation with action on climate change and access to clean household energy (scenario c). This included global action to limit climate change to 2<sup>o</sup>C, through improved energy efficiency and a shift to clean, low carbon energy, plus policies to provide cleaner cooking stoves for an extra half a million people through subsidies and microfinance.
Even this scenario would still leave many people exposed to dangerous pollution levels, with an average global PM2.5 concentration exposure of 26 μg/m<sup>3</sup>. But pollution can be reduced still further by bringing in strict air quality regulation and by policies to introduce universal access to clean cooking fuels and stoves (scenario e). This would mean that pollution levels would be below 35 μg/m<sup>3</sup> everywhere, and more than half of the global population would achieve the safe limit of 10 μg/m<sup>3</sup>.
The health benefits would be dramatic – a reduction in disability-adjusted life-years lost from air pollution (DALYs) from around 60 million (scenario a) to under 15 million (scenario e). Climate action also reduces the costs of air quality regulation by about 40%, as the shift away from burning fossil fuels reduces the need for costly end-of-pipe pollution control methods. Energy access policies are very cost-effective, with huge reductions in health impacts achieved for just $3.5 billion per year (in $US 2005) for the partial energy access scenario, and $17 billion per year for the universal access scenario. The paper estimates the combined cost of all policies as around $1400 billion in 2030, though this would be offset by the health benefits including reduced cost of health care, increased productivity and avoided death and illness (not evaluated in the paper).
The authors conclude that there are significant synergies between the goals of improving air quality, controlling climate change and providing access to clean cooking fuels, with substantial health benefits that would be enhanced by a combined policy.
Rao, S., Pachauri, S., Dentener, F., Kinney, P., Klimont, Z., Riahi, K., Schoepp, W. (2013). Better air for better health: Forging synergies in policies for energy access, climate change and air pollution. Global Environmental Change. DOI: 10.1016/j.gloenvcha.2013.05.003.