The impact of climate policies on European air quality in the 21st century

Abstract : Climate change, long range transport of pollutants andsurface air quality share multiple interaction pathways.Tailoring efficient air quality mitigation strategies overthe long term requires taking into account such externalfactors whose variability can be neglected for short termprojections. We designed, developed and implementeda new regional air quality and climate modelling systemto account for the possible penalties of climate changeand long range transport of pollutants on European airquality. In order to ensure its relevance for environmentalpolicy making, this modelling system is embedded in aquantitative cost-benefit analysis framework.The regional air quality and climate modelling suite allowedproposing an assessment of European air quality in 2050.We highlighted the dominating influence of mitigationof anthropogenic emissions of pollutants in Europe. Butthe penalty brought about by climate change on ozonepollution was also confirmed, and the large impact of longrange transport at the 2050 horizon was emphasized. Forparticulate matter, long range transport is less important;the impact of climate change is significant but alsouncertain.Thanks to the use of air pollutant emission projectionsbased on emission factors reflecting the current legislation,we could assess the costs of climate mitigation and airquality legislation. We point out the economic benefit ofclimate policies for air quality legislation due to a lowcarbon economy requiring less end-of-pipe technologicalmeasures against air pollution. The total cost of mitigation(air and climate) remains however higher under themitigation than under the business as usual pathway.The analysis of air and climate modelling results within amonetised health impact assessment framework allowedassessing expected sanitary benefits. It is important tohighlight that the expected monetised sanitary benefitscompensates the costs of climate mitigation, showing thatair quality can be considered as a positive externality oflow carbon policies.