B787 Flight Attendant reported a high temperature cabin temperature during boarding and during the first hour of the flight. Reporter stated that passengers and crew experienced physiological symptoms due to the temperature.

Narrative

I was Purser onboard this flight. When we boarded the aircraft; I asked the CA (Captain) to get the plane cooled down. Once boarding time (XA:23 hrs) came; the aircraft cabin was still at the same temp; 87°. I asked if the APU was inop and was told that it was working and blowing out cool air. Following the guidelines for boarding a warm aircraft; sec. X.X.X; states; 'do not wait until temperatures reach 90 degrees.' I brought it up to the flight deck four more times in the first 40 minutes. I had already dimmed the windows to 5 and announced for the passengers to open their air vents throughout boarding. Additionally; I spoke several times during boarding with Person A; the person ramping. I also reached out on Company communication twice about the temperature. The cabin temperature raised to 88°; then 89°. I pointed out to Person A and the pilots; once again; that the manual clearly states not to wait until it hits 90°; to be proactive. Person A just kept telling me that it wasn't 90° yet so nothing was to be done. I was clearly the only person being proactive as I could not get anyone else to take any action. We went through business class several times with predeparture beverages and also ice water I made in the galley. The aircraft got to 90° and about the same time; the #2 called and said the pax were getting very angry and unruly in the back. Since I had gotten nowhere with everything I did this entire time; I asked the #2 to come up front to help me communicate this information to the inflight and gate personnel there. #2 had gotten so overheated that he took off his outer shirt and had a t-shirt on underneath. He tried to cool down with wearing just the t-shirt and an apron (the apron was so he was recognizable as flight crew). When he came up; Person A got very concerned about #2 not being in 'full uniform compliance.' Person A started typing messages to the senior manager in charge about #2's uniform. I was extremely disappointed that this disciplinary move was the ONLY actual action I saw going on from the very people I was pleading for help with during our entire hot aircraft dilemma; which was now getting worse. We already knew pretty early in the boarding process that we would be on a maintenance delay because someone had accidentally damaged the outside of the aircraft fuselage. As no one here was new at this job; we all realized it was going to be a while for maintenance to go through the steps in the manual and sign off the logbook. Just as the temperatures kept creeping up; so did our maintenance delay. Pax in the back were shouting and FAs (flight attendants) were worried not only about the safety of pax due to overheating; but also that someone was going to get violent. Still; the only thing being done was a message being sent about #2's full uniform not being worn. After all this time of getting nothing actionable done about the heat; FAs told irate pax to go toward the boarding door to speak with personnel there. Pax were wanting to get off and wanting to get a more realistic time for the delay instead of the 'about another 10 minutes or so' they had heard over and over by this point. The situation was really getting out of control. Incidentally; the coolest place on the aircraft at this point was also in the galley between 2L & 2R because; in an effort to keep themselves from getting sick; FAs had opened the compartment doors so the chillers could be felt by them. I called Dispatch because I couldn't reach the Tower. Dispatch called the Tower for me. I messaged Company. I asked for more management to come down as all my time spent being proactive could not get a single thing done if the flight deck and passenger service refused to take action. Finally; at approx XC:30 hrs; a customer service manager came down; and I explained how out of control the situation was getting. We hadn't gotten much movement on the temperature; the pax were getting angrier and angrier; and the delay was still going on. As Iwas relaying this info to the customer service manager; a pax near door 2L was again loudly saying that it's inhumane for us to keep them on this aircraft. Also; there was an employee; an older; slender in build gentleman in a suit with glasses who suddenly claimed we were 'egging' the pax on. It was then that the customer service manager asked me to go to door 1L with him so we could speak without all this interference. I continued to explain all that had gone on and was going on. The suited employee had followed us up there. I explained that it was 87° when we boarded and I had started sounding the alarms; had climbed to 88°; then 89° and 90°. Suddenly; the suited employee exclaimed that it NEVER got to 90°. I said; yes; it had and that I had even taken a picture of it. I turned the phone to show him the picture and he yelled at me to step back and keep my distance from him. Confused; I looked at the customer service manager; who immediately apologized and said he'd talk to him. I asked the customer service manager if the gentlemen was accusing me of charging him or becoming aggressive. The customer service manager said it appeared that way; but agreed that I didn't do anything; and said; again; that he would have a talk with him. A business class pax then said they could not believe how the man just spoke to me. I then asked the customer service manager if no action had been taken all of this time because of a much too pervasive attitude in our company that I; as the #1 FA; must be overreacting to the situation or something? Am I just being labeled as hysterical; even when I have been calmly advocating for something to be done for over two hours now and had not had a negative interaction with anyone up until now? The customer service manager again said he'd have a talk with the suited employee. We finally got word we were ready to go; closed the door and pushed back at XC:45; 2 hours and 22 minutes after beginning boarding with the 87° temperature. We took off at XD:09. At XD:21; the temp in the cabin was still 83° and our temperature at XD:55; after being in the air for 46 minutes was only cooled down to 77°; even though we had it set much lower than that.Suggestions: I'm not sure how much more I can say other than we HAVE to do better for our passengers. It does absolutely ZERO good for us to have warm aircraft policies if the Captain and the ground personnel refuse to take action. Our passengers entrust us with their safety; and we need to take that responsibility more seriously. Heat exhaustion is a very real thing and poses a very real threat to our passengers' and crewmembers' health and safety. According to the Cleveland Clinic; between 10 and 65% of people with non-exertional heatstroke die from the illness. Some other people experience permanent organ damage or neurological dysfunction; and we cannot always predict who it will affect. However; we CAN provide preventative measures if we all get on the same page with this policy. I pray that this company will not wait to take action until it's far too late to protect someone from irreparable harm. I am willing to be a part of this solution; but I obviously cannot change anything without the support of the other workgroups who are supposed to make up a functioning team that adheres to the policies set forth by the company. Additionally; we have been provided with uniforms that do not breathe properly. We have no summer option; other than to remove outerwear. Why is it not mandatory that we be provided with a summer option of natural materials that breathe in these extreme conditions?