Method for the Detection of Functional Outliers Applied to Quality Monitoring Samples in the Vicinity of El Musel Seaport in the Metropolitan Area of Gijón (Northern Spain)

Air pollution affects human health and is one of the main problems in world, including coastal cities with industrial seaports. In this sense, city Gijón (northern Spain) stands out as 20 Spanish worst air quality. The study aims to identify outliers quality observations near El Musel seaport, resulting from emissions six pollutants over an eight-year period (2014–2021). It compares methods based on functional data analysis (FDA) approach vector determine optimal for detecting supporting control. Our involves analyzing pollutant a set curves rather than vectors. Therefore, FDA approach, are constructed provide best fit isolated points, collection continuous functions. These functions capture behavior domain. Two methodologies were used here: bagplot high-density region (HDR) boxplot. Finally, outlier detection using was found be more powerful method detected HDR