Air Pollution XXIII

"Air Pollution XXIII" contains 37 peer-reviewed papers accepted for the Twenty-Third International Conference on Modelling, Monitoring and Management of Air Pollution, held in Valéncia, Spain in June 2015. The conference series has over the years attracted a global audience of academics and air pollution practitioners who have contributed through their papers and presentations to the evolving understanding of the complex science and policy contexts of air pollution. They have addressed a wide range of air pollution issues and challenges but a particular strength of the conference series has been the attention given to regulatory and, more recently, market solutions to air pollution management. The collected papers from the conferences provide an important record of the development of science and policy pertaining to air pollution. Contributions in this twenty-third volume continue to address a broad range of urgent scientific and technical developments in our understanding of the cause, consequence and management of air pollution.

The subject of the conference series could not be more relevant and significant. In the last year, the World Health Organization has identified air pollution as the world's largest single environmental health risk, with around 7 million people dying annually - one in eight of total global deaths — as a result of air pollution exposure, more than doubling previous estimates. They have also found that while 3.7 million deaths were attributable to outdoor (ambient) air pollution, more than half (4.3 million deaths) were due to indoor (household) sources, both mainly affecting low- and middle-income households. New and emerging epidemiological studies have also revealed that the main health effect of air pollution is cardiovascular (heart disease and stroke) and that ambient air pollution is now a Class 1 carcinogen, equivalent to tobacco smoke.

With more than half the world's population now inhabiting cities, it is alarming to note that only 12% of those reporting on air quality reside in cities compliant with WHO air quality guideline levels. About half of the urban population where air pollution is monitored is exposed to air pollution at least 2.5 times higher than the WHO recommendations. Furthermore, in most cities where there is sufficient data to compare long-term trends, air pollution is getting worse, fuelled by an increasing reliance on fossil fuels in power plants, dependence on private motor vehicles, inefficient use of energy in buildings, and the use of biomass for cooking and heating.

The key sources of local air pollutants are also significant causes of global climate change. This fact, together with the transboundary effects of long-range and precursor pollutants, places a significant burden on governments to reduce the impacts of their activities on public and environmental health not only domestically but globally.

Yet air pollution management is complex, with policies to reduce some contributors having detrimental effects in other areas. The Modelling, Monitoring and Management of Air Pollution series of conferences has consistently acknowledged that science remains the key to identifying the nature and scale of air pollution impacts and reaffirmed that science is essential in the formulation of policy relevant information for regulatory decision-making. The conference series also made clear, at a very early stage, that science alone will not improve a polluted atmosphere. The scientific knowledge derived from well-designed studies needs to be allied with further technical and economic studies in order to ensure cost-effective and efficient mitigation. In turn, the science, technology and economic outcomes are necessary but not sufficient. Increasingly, the conference series has recognized that the outcome of such research needs to be contextualized within well formulated communication strategies that help policy makers and citizens to understand and appreciate the risks and rewards arising from air pollution management. Consequently, the series has enjoyed a wide range of high quality presentations that develop the fundamental science of air pollution and an equally impressive range of presentations that places these new developments within the frame of mitigation and management of air pollution.