Exahust Fan
You've not been in a laundromat on a hot and humid summer's day have you?
Air conditioning isn't an option (would be foolish with all those dryers going), so one has to do something.
Local laundromat leaves the back service door open, and front door as well, along with the fan going, and still wouldn't go there on a hot day.
Problem is the same really for all sorts of commercial laundries, probably worse where ironers and other other heat generating equipment, and or steam boilers are running as well.
If one examines photographs of laundries, old and new, you will see fans (or very large windows). In the days before electricity and or fans, it was HELL to work in a laundry during warm months of the year. And since labour protection laws, and unions weren't that strong, you either put up with it or quit.