I am planning out a fictional game city. Based on the gameplay and story I have decided on several locations which will need to exist. I'm wondering though to what extent I need to take zoning into consideration when planning everything out. For example, there is an industrial area with processing plants, but there is also a residential area fairly close to this.
It is my understanding that industrial areas need to be a certain distance away from residential areas due to health concerns. This varies of course based on many factors, but I'm wondering to what extent I should be considering this when planning out the city. The game in no way requires realistic city planning, but for the sake of not making it obviously unrealistic I'm wondering if there are any rules of thumbs when planning this.