Unless you are going to wait to use the bathroom until you get home,then  public restrooms are the the primary option.

So if you use a bathroom,and it's not properly clean then you are at risk of a infection or illness. Let me also add depending how healthy you are,it can also affect how your cells respond so some people can be affected even more. 

When you are working in a office,and it's not properly sanitized,or clean,then the indoor quality which is vital to our health can be affected which is super imperative as well.

So in conclusion Janitors are as important as all other front line workers because they are the protectors of our health in a public setting.