Stockholm is built on islands that helps, and the rains are not frequent but heavy enough to clean the city a bit, waste management is good. Thera are also fewe

Stockholm is built on islands that helps, and the rains are not frequent but heavy enough to clean the city a bit, waste management is good. Thera are also fewer people are active in the center of Stockholm compared to Paris; Stockholm 5 214 pop/km², Paris 20 909 pop/km² (this disregards important factors about how those numbers work, but it's an interesting indication.)