Post-2015 Consensus: Air Pollution Perspective, Holland
As realization has grown of the impact of air pollution, so too has it become clear that the effects of individual pollutants (particles, SO2, NOx, NH3 and volatile organics) are linked and that they should not be considered in isolation. Health has become the prime driver of air pollution policies in North America and Europe since the mid-1990s, following new analysis that found detectable effects at levels previously considered ‘safe’ and no evidence for an exposure threshold for fine particulates.
Considering Larsen’s paper, the first point concerns the scale of impact, with air pollution amongst the very highest environmental burdens to health according to the Global Burden of Disease Study and the World Health Organization. The scientific basis for this analysis is considered, concluding that the reported size of impact reflects available research, with some potential for underestimation through a lack of quantification for effects of NO2 and long-term exposure to ozone, in particular. Some important questions remain, for example in relation to the types of particle that are most harmful. These questions should not, however, be used as an argument to delay action: they may, for example, make very little difference to policies designed to improve indoor air quality for regions where the use of solid fuels in inefficient, poorly vented stoves is the major source of exposure and impact.
Larsen states that there are four times as many deaths attributed to air pollution as to infant and maternal under-nutrition. However, the average case of child or maternal mortality will account for a much higher quantity of lost life expectancy than the average case of death attributed to air pollution. This is not to say that air pollution effects are unimportant as available data on both deaths and lost life expectancy indicate otherwise, simply that care is needed when making comparisons to ensure that like is compared with like.
In addition to mortality, effects on morbidity also warrant attention. The list of impacts now linked to air pollution is extremely broad, including cancers, respiratory disease (e.g. exacerbation of asthma), cardiovascular disease, stroke, low birth weight and autism. These effects add to the health burden both directly and via the demands that they place on health systems, diverting resource from other areas. They also affect GDP through additional time taken off work by those who are ill, or need to care for sick children or other relatives. The benefits of clean air policies extend beyond health: Larsen discusses reduced fuel costs and savings in time spent gathering biomass, and there are also impacts on ecosystems and cultural heritage (the effect of acid rain on stonework in fine buildings).
Larsen acknowledges that some technical and regulatory options are not considered in his paper. A notable omission is the use of emission ceilings, adopted most famously through the Kyoto Protocol on greenhouse gases, but also through legislation under the UNECE (United Nations Economic Commission for Europe) Convention on Long Range Transboundary Air Pollution, and hence relevant here also. The ceilings define a maximum level of emission of each pollutant for each country. This provides flexibility enabling each signatory to determine how they may most efficiently cut emissions. Though less flexible than an emissions tax, the ceilings provide greater confidence that health and environmental targets will be met.
Moving beyond the scope of Larsen’s paper, there are a number of other factors to be considered in relation to regulation of air pollutants. Perhaps chief amongst these at the present time is interaction between air pollution control and climate mitigation. The chief source of CO2 is the combustion of the same fuels that also generate emissions of SO2, NOx and fine particles. Action to cut CO2 for example through improved energy efficiency can therefore also reduce emissions of the air pollutants of interest here. Indeed, some work has suggested that the health co-benefits of reduced emissions of air pollutants may even exceed the costs of greenhouse gas controls, with the added attraction that these benefits tend to accrue in the short term to those reducing emissions. This contrasts to the benefits of climate mitigation which may accrue to people far way from the site of action, and at some point in the future. On the other hand, some control options for greenhouse gases may worsen air quality (e.g. increased reliance on biomass combustion) and some options for reducing air pollutants may increase GHG emission (e.g. flue gas desulphurization). In the interests of efficiency it is important therefore that mitigation of GHGs and the local and regional air pollutants of interest here is coordinated. The scale of impacts indicates that this action is needed now, as the costs of inaction in terms of health and ecological impact, and the cost of polluting equipment that may become redundant soon after it comes on-line, are very high.