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Air_pollution_main report_WEB

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Chapter 6: The heavy cost of air pollution 6.1 Introduction The development of policy for reducing the risks of air pollution is informed through the quantification and monetisation of effects. Quantification highlights both the magnitude and the variety of impacts. The monetisation process typically accounts for healthcare costs, lost productivity, and 'welfare' or 'utility', placing a value on good health per se. Monetisation permits the costs of action to reduce pollutant exposure to be compared with the benefits, to ensure that there is a sound economic basis for action. In this chapter, particular attention is given to the effects of outdoor (ambient) air pollution, as this has been the focus of a large number of health impact and economic assessments. Reference is also made to some work on indoor air quality, but this focuses on specific examples (second-hand smoke and radon) and is significantly less complete. Quantification is limited to effects for which there is considered to be sufficient evidence available, not only for acceptance of effect, but also for quantification. Important elements of the emerging literature on childhood illness, in particular, have yet to be taken through to quantification. 6.2 Outdoor air pollution 6.2.1 Methods All of the major air pollution health impact assessments follow the same broad method, referred to as the impact pathway approach, which was first elaborated in detail in the EC–US Fuel Cycles Study of the early 1990s, a collaborative exercise between the European Commission and the US Department of Energy. 1 This approach tracks air pollution from its source in a logical, sequential manner, to describe the exposure of the population and then the impacts on the population either as a whole or for specific groups (eg those over the age of 65 years, or children with asthma). The development of methods by various bodies, including the UK's Committee on the Medical Effects of Air Pollutants (COMEAP), 2,3 the US Environmental Protection Agency (USEPA) 4,5 and the WHO, 6 has required a number of decisions to be made, of which the following are particularly important: • Analysis is based on the use of data from epidemiological studies in preference to toxicology, in order to capture effects on the whole population, and a full range of effects from those that range from mild to severe for individuals. • Various reviews of evidence from the western hemisphere have concluded that analysis should focus on exposure to fine particles (PM 2.5 ) and O 3 . There is growing evidence for inclusion of additional impacts of exposure to NO 2 and these effects are now being integrated with damage assessments. • PM 2.5 is a complex mix of primary and secondary particles, varying in their physical and chemical characteristics. However, available evidence does not support a systematic distinction between different particle types within the PM 2.5 size range. • Epidemiological research of fine particles has found no evidence for a threshold at the level of the whole population. 7 For O 3 , expert opinion 8 has concluded that, while there is no firm evidence 80 © Royal College of Physicians 2016

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