Overview map of the study area.
1a shows the 98 municipalities of Denmark with two boxes indicating areas where clusters were detected. 1b shows an enlargement of the Odense area. 1c shows an enlargement of the Copenhagen area with names of the municipalities referred to in the text. The colours indicate for each municipality the density (number of addresses per square kilometre) of geo-coded residential addresses included in the study. The maps contain data from the Danish Geodata Agency.