Pollution level using dictionaries

[Terafy]

Ah sorry I'll be more direct.

You can't use sum(pollution). Because pollution will be just a number which is why you got:

Error:
TypeError: 'int' object is not iterable.

And you forget that you input data (januar) contains the pollution for each city per day. You are not trying to find the cities combine average pollution per day. You trying to find average pollution of a city.