Use of the APU on stand
What are the rules on APU use over the summer months if an aircraft is just sitting in the sun on a 90 minute turn around. Do they make the cleaners work in a non cooled environment? I know some airports are really strict on this (hello LCY) but does runnning an APU really make any dent in pollution or noise when compared to jet engines?
Is non use of the APU a legal thing or part of the Ts and cs which vary by airfield?