Date: 201906
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Aircraft: EMB ERJ 170/175 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Climb
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Human factors: Physiological - Other
Second reporter function: Flight Attendant In Charge
Anomaly: Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor; Flight Deck / Cabin / Aircraft Event Illness / Injury
Detector: Person Flight Attendant; Person Flight Crew
When detected: In-flight
Result: Flight Crew Returned To Departure Airport; General Maintenance Action
Contributing factors: Aircraft; Human Factors
Primary problem: Aircraft

Narrative: The airplane had quite a logbook history of dirty sock odor/various packs being MELed and signed off; etc.; but the crew that had brought it in (had the same First Officer/Flight Attendant A/B; but was taking over as Captain) had been quite delayed due to the previous Captain rejecting the aircraft in ZZZ and subsequent engine run where I was told they had some kind of fume event during the engine run. However; at some point it appeared 'resolved' after the high power engine runs that they did and Maintenance had signed off the aircraft. Pack 2 was deferred due to the dirty sock odor as the fix. It was an ECS [Environmental Control System] off takeoff due to the pack on MEL so the APU was left running. We departed for ZZZ2 and shut down the APU shortly after the flaps zero call. Approximately 5;000 feet (around ZZZZZ Intersection) a dirty sock/moldy type odor permeated the flight deck. The odor was nauseating and made me dizzy; both First Officer and I smelled it; and we donned our oxygen masks per the memory item and I told him we would return to ZZZ1. I gave the First Officer the airplane and radios; he let ATC know and I talked to the FAs via the emergency call button. FA-A said there was a strong odor in the forward galley and the passenger in XC was complaining he could smell it; and that her eyes were watering and she felt dizzy and nauseous. I continued setting up the FMS and did a quick approach brief; and once we were caught up took the controls back from the First Officer and he resumed radio duties. ATC told us they had [advised] for us. I made a very brief PA to the passengers at some point letting them know we were returning. We had an uneventful landing; taxied off the runway and the smell had dissipated by that point. We were immediately given a gate by Tower/Ops who did a great job coordinating for us. Unfortunately; when we got to gate with the firetrucks following us ready to offer assistance to us and any passengers; it would be almost 18 min before we blocked in because there was initially no rampers and then almost a 10 min delay to get a jet bridge driver. To my knowledge; although the passenger in 1C reported odor; nobody requested medical attention. However; I asked to get checked out by the paramedics because I was experiencing fume inhalation symptoms and felt very unusual. I have experienced dirty sock fumes before with no symptoms but this time felt very different. FA-A also felt terrible - I talked to [personnel] who was extremely helpful and supportive and the paramedics asked if we wanted to go to the hospital. Based on how I felt; and that my symptoms almost exactly mirrored FA-A; we decided to take an ambulance ride to the hospital to get checked out. The First Officer decided not to; as he was feeling better than the two of us were. At that point [personnel] asked me to tell him to please go to the hospital as well to be on the safe side. FA-B reported no symptoms as she was in the back of the aircraft and did not go to the hospital. At the hospital; I provided the health care providers with the fume guidance for health care provider form; they noted an abnormal elevated level of met hemoglobin in both myself and FA-A and said that we definitely had been exposed and inhaled something. Throughout this event the company was extremely supportive and helpful and I would like to commend them.The smoke/fire/fumes checklist/QRH should be split into an 'odor/fumes' QRH that gives more guidance for this type of scenario. Maintenance needs to look into the procedures for an aircraft being signed off after a cabin air quality event. There can be serious consequences for crews with even low levels of exposure to cabin air intoxicants and I would suggest working with [the airlines] who have done a lot of work already on this front that we don't need to re-duplicate; [Company] has come up with a lot of their own equipment such as sniffers. It is hard to imagine that 'coffee' exposure would lead to elevated met hemoglobin in both myself and the FA and whatever substance is found in the packs/heat exchangers should be sent to a professional lab and tested.


Second narrative: While conducting pre-flight procedures on Aircraft X ZZZ-ZZZ1; Captain informed me there were numerous logs for 'engine fumes in the cabin' from previous crews. To my recollection he said 5 in the last week; but later I was informed it was 11 write-ups in 16 days and one deferred PAC. I had previously operated on numerous flights where these same issues of toxic smells were of concern by both pilots and flight attendants. I also have boarded jets when the outgoing crew members had briefed us about [the] smell of fumes. Captain and First Officer spent hours on the ground with the Chief Pilot; Dispatch; gate agents; ground crew and Maintenance addressing the issue. It was apparent from the conversations I heard; [Company] wanted the issue deferred and the flight to depart. Eventually with the insistence of Captain and First Officer; it was agreed that Maintenance Personnel would be dispatched to the aircraft. When the aircraft Mechanic arrived; intense discussion arose as to the airworthiness of the aircraft with the ongoing fume issue. It was determined the pilots; Maintenance and with both myself and [another] Flight Attendant would taxi out from the gate; engines were to be ran up to recreate the toxic fumes in the cabin. As expected; the cabin did fill with fumes. [The other] Flight Attendant and myself reported the presence of strong fumes in the cabin. The pilot and Maintenance also acknowledged they had smelled the same toxic air. When the engines were ran up; I immediately felt sick to my stomach; my face started to burn and I felt lightheaded. We were trapped in aircraft with no fresh air for hours. After running up the engines; the pilots exited the aircraft along with Maintenance Personnel and walked around the aircraft. At this point; the Mechanic put oil in the engine then were we instructed to conduct additional engine runs again. This time; there were no detectable fumes. Personally; I believe that the toxic fumes come from leaking oil burning off in the engine. Eventually; we were instructed to board the aircraft for the second time.We arrived ZZZ1. Captain was replaced with [another] Captain. I was still working the FA-A position. When the main cabin door was opened; I was instantly rushed and confronted by the Gate Agent as to when would we be able to board the next flight to ZZZ2. At this point; I asked Captain A if they were actually having us operate the same aircraft to ZZZ2. He said yes; but he was not flying it. There was obviously something wrong with the jet. I was extremely disturbed by the reality of the situation and what we had been through that day. I even said this is absolutely not acceptable. I was appalled we were being pressured to operate that aircraft to ZZZ2. I was under the impression from the first Captain once we got the aircraft to ZZZ1 it was going to be turned over to Maintenance. I expressed this concern to the crew. At this point I was already not feeling well.We were pressured and intimidated into continuing on with flight. While the aircraft was climbing out of ZZZ1; my eyes started to burn and water. I felt a feeling of nausea then dizziness. At about this same time; I could hear the use of EMERGENCY oxygen sounds coming out of the flight deck. I was just about to push the FA call button to ask FA-B if she could smell the fume odor again when the RED emergency pilot button sounded. I picked up the interphone was instructed by Captain that we were making a diversion back to ZZZ1. At that point; training kicked in I had my pen and announcement guide ready for TEST items. I call FA-B relay the Captain information. The Captain then made an announcement to the passengers that we were diverting back to ZZZ1 and that response personnel would meet the aircraft. We stayed seated until the jet was back on the ground at ZZZ1. Once on the ground; we were met by emergency personnel. The passengers were deplaned. At that point; I was seated in row one with wet paper towel on my eyes. I was feeling extremely ill. The paramedics took my vitals and advised me to go to the ER. Flight Attendant B said she was not going to the ER. First Officer took an [ride] to the ER.I was treated for toxic inhalation; burning and swelling to my face and neck and dehydration. I was administered fluids; steroid and diphenhydramine through IV treatment. In addition I had a chest XRAY and an ECG. The ER doctor told me to follow up with a pulmonary doctor and my primary care physician. Tests ran at the ER confirmed both myself and Captain had methemoglobin in our blood from exposure to various chemicals. I have been extremely ill since this incident with headaches; nausea; dizziness and burning to my face and neck.Suspected engine oil fumes contaminating the cabin air system due to improper Maintenance. This was an ongoing issue with this aircraft it had been written up 11 times in 16 days and also had a deferment. Management required us to operate an unworthy aircraft. We were pressured into operating from ZZZ-ZZZ1 and then again ZZZ1-ZZZ2. There was no Maintenance check of the aircraft before departure to ZZZ2. The toxic fume issues was not resolved which resulted in a return to our departure airport. Sequentially; crew members were taken to the ER for toxic fume inhalation.


Synopsis: EMB-175 Captain and Lead Flight Attendant reported a fume event shortly after takeoff resulting in a return to departure airport. The entire flight crew and a passenger experienced health issues and were administered medical treatment.