Poor urban air quality is one of the main environmental concerns worldwide due to its implications for population exposure and health-related issues. However, the development of effective abatement strategies in cities requires a consistent and holistic assessment of air pollution processes, taking into account all the relevant scales within a city. This contribution presents the methodology and main results of an intensive experimental campaign carried out in a complex pollution hotspot in Madrid (Spain) under the TECNAIRE-CM research project, which aimed at understanding the microscale spatio-temporal variation of ambient concentration levels in areas where high pollution values are recorded. A variety of instruments were deployed during a three-week field campaign to provide detailed information on meteorological and micrometeorological parameters and spatio-temporal variations of the most relevant pollutants (NO2 and PM) along with relevant information needed to simulate pedestrian fluxes. The results show the strong dependence of ambient concentrations on local emissions and meteorology that turns out in strong spatial and temporal variations, with gradients up to 2 μg m-3 m-1 for NO2 and 55 μg m-3 min-1 for PM10. Pedestrian exposure to these pollutants also presents strong variations temporally and spatially but it concentrates on pedestrian crossings and bus stops. The analysis of the results show that the high concentration levels found in urban hotspots depend on extremely complex dynamic processes that cannot be captured by routinely measurements made by air quality monitoring stations used for regulatory compliance assessment. The large influence from local traffic in the concentration fields highlights the need for a detailed description of specific variables that determine emissions and dispersion at microscale level. This also indicates that city-scale interventions may be complemented with local control measures and exposure management, to improve air quality and reduce air pollution health effects more effectively.
Bibliographical noteFunding Information:
This study was carried out within the TECNAIRE-CM (innovative technologies for the assessment and improvement of urban air quality) scientific programme funded by the Directorate General for Universities and Research of the Greater Madrid Region ( S2013/MAE-2972 ). InterMET is thankfully acknowledged for their assistance. Ángeles Cristobal, Ana Rosa Llorente and Carlos Rubio from the Madrid City Council and Juan Huerta from CTRM collaborated very closely and made the experimental campaign possible. Iberdrola granted access to their facilities and kindly helped with the logistics of the campaign. The International Consortium for Urban Environmental Health & Sustainability (Healthy-Polis) is also acknowledged for providing the DustTrak™ DRX instrument.
- Air quality
- Experimental campaign
- Urban hotspot