Abstract Background Wheezing among children below the age of six (pre-schoolers) is common and often triggered by environmental factors. Moreover, evidence on which to base recommendations for its management is limited, resulting in high numbers of prescriptions and costs. This study aims to describe the spatial differences in asthma medication sales for children aged 0 to 5 years in Belgium, and to evaluate the correlations with socio-economic and environmental factors.. Methods This ecological study includes information on prescribed and sold asthma medication (R03 ATC code) for all the pre-schoolers registered in Belgium, aggregated at the municipality and smaller administrative levels, in 2014. A case was defined as a pre-schooler having purchased prescribed R03 medication at least once in 2014. We mapped the number of cases, the prevalence of medication purchase (n cases/n registered pre-schoolers) and the costs per case (â Ź) at different administrative levels. We used symbol maps for the number of ...