Application of an air quality action plan in Madrid
Within the framework of the Tecnaire-CM project, in which UPM researchers were involved, diagnostic and analysis of short-term air quality in Madrid under a high-pollution episode using advanced techniques has been carried out.
In spite of the recent efforts to enhance air quality in cities, the atmospheric pollution is still a big issue in urban areas. Besides the policies and plans to reduce polluting emissions, exceptional measures are needed when high-pollution episodes occur under unfavorable weather conditions.
This type of measures is included in the city council Protocol for high-pollution episodes caused by NO2 nitrogen dioxide emissions in the city of Madrid. This event occurred in 2016 when the stage 3 of such Protocol was activated for the first time in Madrid and set a speed limit and parking limit as well as access restrictions for road traffic to the center of Madrid.
The researcher team of the Tecnaire – CM project carried out a monographic analysis on the high-pollution episode and the application of the N02 protocol in Madrid.
Firstly, they conducted an analysis of meteorological observations and diverse parameters of air quality that suggest that the episode is clearly associated with the conditions of atmospheric stability and low wind speed and is linked to a phenomenon of thermal inversion. The overall analysis of the observations also suggests that the measures associated to the stage 3 prevented the No2 concentration increased up to 15% in some spots in the city center of Madrid.
In addition, a simulation of the episode with and without the adopted measures was carried out using a multi-scale model in 1 km2 resolution and based on the WRF-SMOKE-CMAQ models. To study the effect at street level they used Star-CCM+ (RANS CFD model) at microscale domain in the city center of Madrid (Gran Via street). Changes in road traffic were simulated with the mesoscale VISUM model, incorporating real flux measurements during those days.
The conclusions obtained from the simulations suggest that the application of the protocol during this particular episode could have prevented that concentrations from increasing up to 24 micrograms per cubic meter (14% respect to the hypothetical no action scenario) although it may have caused a slight increase of NO2 in the city outskirts due to traffic redistribution.
The simulation results provide a strong overview of the diverse scales. However, the detailed analysis allows us to understand what strategies are most likely to be effective at a local level.
However, more research is needed to accurately estimate the effect of the adopted measures. The results suggest that under adverse meteorological conditions it is difficult to reduce the concentration levels and only by applying drastic measures such as restrictions for road traffic we can achieve a significant impact. This highlights the importance of a short time action plan and to set measures of permanent reductions related to long term policies of air quality that allows us to reduce the levels of atmospheric pollution throughout the year.
TECNAIRE (Innovative technologies for the assessment and improvement of urban air quality) is a scientific programme funded by the Directorate General for Universities and Research of the Greater Madrid Region. The involved research groups in this project are from Universidad Politécnica de Madrid (UPM), Universidad Complutense de Madrid (UCM), Consejo Superior de Investigaciones Científicas CSIC and Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT) along with diverse associated companies and the areas of air quality of the city council and the region of Madrid.