Commercial Fixed Wing
Flight Attendant Current
Flight Attendant Airline Total 3
Troubleshooting; Physiological - Other; Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Illness / Injury
General None Reported / Taken
Aircraft; Weather; Human Factors; Environment - Non Weather Related
The APU went out on this plane before landing initially in ZZZ.  Of course; it was deferred and we were cleared to return to ZZZ1.It was a warm day - not exceptionally so; but hot. These airplanes retain heat all the time; but with a broken APU; the plane becomes a miserably hot metal tube.I had a plane at maximum capacity with a lot of large; hot passengers.  I also had a plane with elderly passengers; small; crying children; and people who did not understand English. All were compliant with the masks; but I also know those masks are dangerous in heat.  The CDC has listed these warnings on their website and in their tweets.  I was very concerned about their health and the heat inside the cabin.While returning the cart to the galley after service; I began to get light headed.  I stood behind the bulkhead (away from passenger view) and removed my mask to breathe oxygen.  I also had to fill a glove with ice to put on the back of my neck to cool myself.  I was very concerned; if I felt that way on a spring day what are the rest of my plane of passengers experiencing?Masks are a very serious and concerning safety issue on hot planes - especially this type and especially when temperatures are climbing.  The summer is going to be a hazard to everyone's masked health - including customers and crew.The mask policy on airplanes needs to be reviewed by the FAA - especially on this make and model.  There are serious safety issues caused by the mask mandates.  Anyone with asthma; heart conditions; lung issues and those who are extremely obese are already at risk when their bodies are exposed to heat.  Constricting their ability to breathe oxygen and fresh air is a danger in HOT spring and summer conditions.  I was taught in training that crew members are more susceptible to hypoxia in the air; but now that threat is greater with FAs flying in masks in hot metal tubes at high altitudes.
Flight Attendant reported health concerns for the crew and passengers having to wear face masks after the APU was inoperative and the cabin temperature was hot.