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. Flight attendant-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. Flight attendant-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 flight attendant-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. Flight attendant-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 flight attendant-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 flight attendant and whatever substance is found in the packs/heat exchangers should be sent to a professional lab and tested.

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Original NASA ASRS Text

Title: 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.

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.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.