Multicriteria approach to interpret the variability of the levels of particulate matter and gaseous pollutants in the Madrid metropolitan area, during the 1999e2012 period P. Salvador a, * , B. Artí ~ nano a , M.M. Viana b , A. Alastuey b , X. Querol b a Environmental Department of the Research Center for Energy, Environment and Technology (CIEMAT) e Joint Research Unit to CSIC-CIEMAT “Atmospheric Pollution”. Avenida Complutense 40, 28040 Madrid, Spain b Institute of Environmental Assessment and Water Research (IDÆA-CSIC). C/Jordi Girona 18-26, 08034 Barcelona, Spain highlights  Trends in ambient pollutants concentrations were analysed over 1999e2012.  Environmental policies on air quality produced a beneficial effect in this period.  Fuel consumption and anthropogenic activities diminished due to the economic crisis.  To reduce future exhaust emissions Euro6/VI vehicle generation should be introduced.  To reduce future PM non-exhaust emissions, the volume of traffic should be reduced. article info Article history: Received 20 November 2014 Received in revised form 2 March 2015 Accepted 5 March 2015 Available online 6 March 2015 Keywords: Urban air pollution Trend analysis PM 10 PM 2.5 Gaseous pollutants Air quality policy abstract The evolution of the mean levels of particulate matter (PM) and gaseous pollutants recorded in the Madrid metropolitan area from 1999 to 2012, were investigated focussing on the impact of mitigation strategies and economic scenarios. Temporal trends have shown that SO 2 , CO, NO, PM 10 and NO 2 levels at Madrid kerbside and urban-background sites have been decreasing over the 1999-2012 period, with statistical significance. A small contribution to the annual decreasing rates of SO 2 , NO and NO 2 obtained at these sites could be attributed to the reduction in the regional background levels. The reduction in the emissions of atmospheric pollutants from specific sources of the urban agglomeration, explained most of the annual decreasing rates obtained at the kerbside and urban-background sites. From 1999 to 2007 a reduction of the emissions from road traffic and residential heating was produced, as a consequence of the implementation of a number of management strategies promoted and adopted by European and national public administrations. In contrast, from 2008 to 2012 a deep decrease in fuel consumption and a reduction of construction-demolition and roadwork activities took place in the Madrid metropolitan area, as a consequence of the economic recession. The expected overcoming of the economic crisis within the next few years, will presumably give rise to similar levels of PM and gaseous pollutants as those existing previously to the crisis period. The introduction of new Euro 6/VI vehicles which emit consid- erably less NO x than previous generation diesel vehicles, as well as the implementation of strategies aimed at reducing resuspended mineral dust from road traffic and construction-demolition activities are thus encouraged. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction Urban air pollution has become an environmental issue of public health concern (Nel, 2005; Pope and Dockery, 2006) being also the source of other problems such as damage to materials, cultural heritage, buildings and vegetation in and around the city (Akimoto, 2003). A considerable amount of new information indicates that * Corresponding author. CIEMAT, Avenida Complutense 40, Edificio 23, P0.2e. 28040 Madrid, Spain. E-mail address: pedro.salvador@ciemat.es (P. Salvador). Contents lists available at ScienceDirect Atmospheric Environment journal homepage: www.elsevier.com/locate/atmosenv http://dx.doi.org/10.1016/j.atmosenv.2015.03.008 1352-2310/© 2015 Elsevier Ltd. All rights reserved. Atmospheric Environment 109 (2015) 205e216