Elemental carbon as an indicator for evaluating the impact of traffic measures on air quality and health

From 2005 to 2009 there was a 40% decrease in the number of days on which the European daily limit value of PM10 was exceeded at traffic locations in European cities. Yet, in many of these cities, air quality is still not in compliance with the European Air Quality Directive and additional traffic measures are planned. Our study shows that elemental carbon (EC) is a more appropriate indicator than PM2.5 and PM10 for evaluating the impact of traffic measures on air quality and health. The modelled improvement in EC concentration was translated in life years gained as a result of a traffic measure. This was investigated for a speed management zone on a motorway in the city of Rotterdam. Eighty-five per cent of those living within 400 m of the motorway gained 0–1 months of life expectancy and another 15% gained 1–3 months, depending on their distance from the motorway. In addition, EC was used to evaluate a low emission zone in Amsterdam, specifically for those living along inner-urban roads with intense traffic levels. The zone only restricts heavy duty vehicles with Euro emission class 0 to 2, Euro 3 older than eight years or more recent Euro 3 without diesel particulate filter. The results indicate a population-weighted, average gain of 0.2 months in life expectancy as compared with a maximum potential gain of 2.9 months. It is concluded that on motorways speed management is an effective measure, while a low emission zone as implemented in our case study, is less effective to reduce health effects of road traffic emissions. For inner-urban roads reduction of traffic volume seems the most effective traffic measure for improving air quality and health.