B737-800
Physiological - Other
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
General Maintenance Action; General Flight Cancelled / Delayed; General Physical Injury / Incapacitation
Aircraft
Aircraft was boarded and we were about to close the boarding doors. Captain had made an announcement for passengers and flight crew to deplane and take their belongings that he had smelt an odor coming from the lavatory. It wasn't alarming but he wanted everyone to step off the aircraft. Captain had called back to crack the back doors; he didn't know at that point if it was throughout the aircraft in ventilation system. FA C had cracked the back doors L2 R2 for ventilation. I was in mid cabin when originally announced to deplane. I had assisted passengers and moved my way aft to see what was going on. When I approached the aft galley the smell of fuel fumes were overpowering; C FA pointed out the fire extinguishers; just saying; the fire extinguishers are right there if needed; like prepping our heads to think fast & be a step ahead. I stood momentarily and had to move forward the smell of fumes was so overpowering I instinctively had to move forward by aft lavatories. After all passengers deplaned; maintenance came on board and discussed with Captain and FO what the problem was [while I] was standing near vicinity of lavatory. Captain was adamant to step off aircraft and finish discussing the issue in jetway. It was at that point I became aware of the concern. When the Captain and FO had used the forward lavatory they had smelled a chemical smell that had burned their nose; throat; and chest. It had gotten worse after exposure initially. Pilots had heard FA D coughing and asked if he was okay. Smell and reaction was so strong that Captain had compared it to a pepper spray he had experienced in the past. Since others had the same reaction as he did; he decided to deplane. We had initially come in on this aircraft from ZZZ1 to ZZZ and had a slight grounding before next flight was to board. I was in fwd galley between flights when fleet services came on to clean between flights. I saw the man who cleaned lavatory and didn't notice anything at that time. The point I noticed a pressure sensation and burning sensation in my chest was in the jetway after deplaning. There were three passengers who used the lavatory prior to the incident during boarding. I had seen the third passenger come out of the lavatory and return to her seat prior to door closure; she had appeared fine; just excusing herself for she seemed to have felt she was in the way returning to her seat. Flight Crew was quarantined & passenger was located to come to jetway with us. Aircraft was swept by Hazmat. All of crew; besides C FA who wasn't feeling any symptoms; was met in jetway by medics and assessed; as well as passenger & CSA who boarded plane to gather items left behind by passengers. Oxygen was put on Captain; FO; Flight Attendant D; & CSA agent; and [passenger] which helped their symptoms of burning nose; throat; & chest. I had been escorted to the outside ground restroom after breathing in the fresh air my symptoms were relieved. After the aircraft was swept; Captain had advised us all to get checked out at hospital to make sure we were all fine. Ambulance took myself FA B; FA A; FA D; Captain; FO; and CSA agent to be assessed at hospital and then released from hospital; cleared by [company]; and met with in flight supervisors in ZZZ.
B737-800 Flight Attendant reported while at gate the Captain ordered all passengers and crew to deplane due to strong chemical odor on board. While assisting in passenger deplaning the entire crew experienced physiological symptoms and subsequently received medical treatment.