Volume X |

Observation of Unusual High Particulate Mass and Number Concentration during Traffic Ban Hours of the 2009 Car Free Sunday in the Brussels Urban Area

Abstract: Every year, since 2002, the Brussels authorities organize a car free day on the third Sunday of September. This very interesting experience has revealed some valuable information concerning traffic-related gaseous pollutants and particulates. On the car free Sunday of 2006 very high PM10 and PM2.5 mass concentrations were measured, along with very low concentrations for nitrogen oxides, carbon monoxide and dioxide. The car free Sunday of 2009 also showed very interesting results. During the traffic ban hours, particulate mass concentration and particulate number concentration peaked to one of the highest values for the whole year 2009. Black Carbon however was the only measured particulate component whose concentration continued to decrease during the traffic ban period.

Volume IX |

Particulate Matter and Nitrogen Dioxide in the Brussels Ambient Air. To What Extent Local Emission Reductions Need to Be Drastic to Enable Compliance with the EU Limit Values

Abstract: Over the past 40 years ambient air quality in Brussels improved significantly. This was especially true for sulfur dioxide, lead, nitrogen monoxide, carbon monoxide, benzene and Benzo a pyrene. With respect to the air quality objectives imposed by the most recent European directive on air quality, 2008/50/EC, two major problems remain: nitrogen dioxide (NO2) and particulates (PM10 and PM2.5). Although the air quality objectives are met at several measuring sites in Brussels, a thorough analysis of data shows that it will be impossible to become fully compliant, in due time, in all of the different urban environments. A comparison of the average concentration levels in the Brussels Capital Region with those in the surrounding regions, the interpretation of the average daily and weekly concentration profiles and some special observations (e.g. car free Sundays) make clear that drastic emission reductions will be needed if compliance is to be assured solely by measures on the local scale.