Further Improvement of Air Quality in China Needs Clear Ammonia Mitigation Target

Setting ammonia mitigation targets requires a clear understanding of the relationship between emissions and impacts, with the aim of reducing impacts at minimal cost. The level of socially acceptable impact, or of the economically acceptable cost, then determines the target chosen. This can be done using cost-effectiveness and cost-benefit analysis, although recognizing that health-related costs (beyond the costs of health treatment as such) are extremely difficult to quantify. Alternatively, guidance can be taken from costs that have already been considered as acceptable. Costs of the current air pollution control policies in China are estimated to be in the order of billions of Chinese Yuan; attributing an adequate share of these costs to the reduction of agricultural ammonia emissions would enable the realization of the improvements. The above provides an agenda of research priorities and highlights the need to develop proper institutions. Based on a harmonized ammonia emission inventory, measures specific to Chinese conditions can be identified, their effects quantified, and their implementation costs and limitations assessed. The clear relationship between emissions, atmospheric processes (PM concentration, nitrogen deposition), and impacts on human health and terrestrial and aquatic biodiversity needs to be established across the range of regionally differing conditions. Further research can address the effects of other atmospheric constituents on NH3 and PM2.5 concentrations. We believe the opportunities to develop such a multieffect strategy exist, not least because of the political recognition of the seriousness of air pollution in China, as also reflected in the formulation of the Green-Agricultural-Development program. The European experience, although far from complete, demonstrates the potential of this approach and the scientific tools and technologies that are available for emission abatement.