Combining Modelling with Clustering Analysis to Characterise Exceedances of NO2 Concentrations in the Metropolitan Area of Buenos Aires

Ground-level air pollutant concentrations are known to present marked spatial variations in the urban atmosphere. In large urban areas, air quality models can contribute to assess potential exposure concentration levels. The Metropolitan Area of Buenos Aires (MABA), the third mega-city of Latin America, concentrates around 13 million inhabitants in approximately 3830 km². However, despite of its extension and the potential impact of air quality on human health, only a few monitoring campaigns have measured ground-level nitrogen dioxide (NO₂). In this work, an urban scale atmospheric dispersion model (DAUMOD-GRS) is applied in the MABA, considering three years of hourly meteorological information and a high resolution (1 h, 1 km²) emission inventory to analyse potential exceedances of urban background NO₂ hourly concentrations of its corresponding air quality standard (200 ppb) and the one suggested by the World Health Organization (110 ppb). When the WHO criterion is considered, despite of the low (2 to 1979 km². In order to classify leading conditions and their spatio-temporal distributions, a clustering analysis including all relevant variables associated with exceedances is performed. Results indicate that exceedances can be grouped into six families with different characteristics and marked spatio-temporal distributions.