Abstract
Road traffic is a major source of urban air pollution responsible for substantial premature mortality. Until recently, attention has focussed primarily on exhaust emissions of particulate matter from traffic as a causal factor. From analysis of air quality measurement data from the UK and France, we demonstrate that road traffic exhaust has a far greater impact on concentrations of nitrogen dioxide than of PM2.5. PM2.5 and carbonaceous particle concentrations have been declining appreciably since 2010/11 due to the use of diesel particle filters, but little change is seen in nitrogen dioxide over the period from 1995 to 2015. It is shown that the effect of NO2 from road traffic upon premature mortality was ten-fold greater than that of PM2.5 even before the widespread use of diesel particle filters, and is now considerably larger. The overwhelming contribution of diesel compared to gasoline-fuelled vehicles to emissions of both PM2.5 and NO2 emphasises the importance of further controls on emissions from diesels.
Highlights
The adverse effects of air pollution exposure on human health are well established[1,2,3,4,5], and the recent Volkswagen emissions scandal has highlighted the contribution of engineering controls in the achievement of improved air quality
The trends in annual mean concentrations of particulate matter mass expressed as PM10 and PM2.5, particle number, elemental carbon (EC) and organic carbon (OC) appear in Fig. 1, and Supplementary Table S1
Since exhaust emissions of particulate matter are made up predominantly from EC and organic matter, an approximate mass can be estimated from the sum of EC + 1.2 OC21
Summary
Road traffic is a major source of urban air pollution responsible for substantial premature mortality. Catalytic converters fitted to gasoline-powered vehicles have led to huge reductions in airborne concentrations of carbon monoxide and benzene in cities throughout the developed world[6, 7], but despite their well demonstrated adverse effects on human health, particulate matter[8, 9] and nitrogen dioxide[10, 11] have yet to be adequately controlled. We have used routine ambient air quality measurements downloaded from the UK Automatic Urban and Rural Network[17] and Airparif[18] for such paired sites in London, Glasgow and Paris in order to evaluate the change in vehicle emissions over recent years since the introduction of diesel particle filters and the implementation of the stricter Euro regulation for NOx emissions
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