Tourism
Tourism's mechanics are the same as Education; each turn it's modified the following way:
- Reduce the total by 4%. This applies to positive or negative tourism, so it'll trend towards 0.
- Decrease by the city's population, so a size 10 city will lose 10 tourism per turn (in addition to the decay).
- Add the tourism provided by the buildings in the city
The same trick to calculate limit education also applies to tourism (25 times the difference between tourism provided and city pop).
Tourism has the following effects (only the cumulative effect is displayed here, not the individual effect of each Tourism level):
Column 1 Column 2 Column 3 Column 4 Column 5 Column 6 Column 7 Column 8 Column 9
Tourism Last Tourism level %

%

Crime Disease Air pollution Water pollution
10 to 24 Tourism (Level 1) 10 10 1 10 5 5 5
25 to 49 Tourism (Level 2) 20 20 2 20 10 10 10
50 to 99 Tourism (Level 3) 30 30 3 30 15 15 15
100 to 249 Tourism (Level 4) 40 40 4 40 20 20 20
250 to 499 Tourism (Level 5) 50 50 5 50 25 25 25
500 to 999 Tourism (Level 6) 60 60 6 60 30 30 30
1000 to 2499 Tourism (Level 7) 70 70 7 70 35 35 35
2500 to 4999 Tourism (Level 8) 80 80 8 80 40 40 40
5000 to 9999 Tourism (Level 9) 90 90 9 90 45 45 45
>= 10000 Tourism (Level 10) 110 110 10 100 50 50 50
There's no penalty to having negative tourism (apart from needing more to reach a positive value later on).
From this Table RWN compiled you will notice that Crime is introduced at Twice the rate of all other Malus. With the Current Crime system this is too strong. It should match the progression rate of the other 3 malus that use the Property system.
EDIT: so much for the new Forum system to let you organize a copy/paste.
JosEPh