Date: 201903
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class B ZZZ
ATC / advisory: TRACON ZZZ
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Instrument; Flight Crew Commercial; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Human factors: Physiological - Other
Anomaly: Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Illness / Injury; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Person Flight Crew; Person Flight Attendant
When detected: Taxi; In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Landed As Precaution; Flight Crew Returned To Departure Airport; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: All preflight preparations at the gate went as normal. The only non-standard procedure was an MEL for IDG 2 that required the crew to have the APU on for the entire flight (electrical use only). Pushed out of gate and started both engines for the short taxi for XXR and left the APU running as per the MEL. Once on taxiway B heading east; we joined the slow moving line for takeoff. During this time both the First Officer and I experienced the smell of jet exhaust in the flight deck. Based on our current location at the time; I considered the smell to be normal and assumed that once airborne the smell will go away (like any other flight). I do not recall the taxi time precisely but; to the best of my recollection; I believe we taxied for about 15 minutes. After takeoff and during climbout the smell was still present and strong. As we initiated the turn east I felt a little light headed; however; I didn't give it much attention and continued my pilot flying duties. As we climbed through 10;000 feet; the smell was still present with the same intensity. At that point I asked the First Officer if he was sensing the smell and he said yes; but like myself; he also thought the jet exhaust smell was going to dissipate after takeoff. I also called the flight attendants to ask them if they were experiencing the smell in the cabin. The Flight Attendant lead informed me that they all smelled the jet exhaust type smell in the cabin and some of them started to feel light headed.At that point I commanded the First Officer to put the oxygen masks on; leveled the airplane off at 19;000 feet and [advised ATC]. I directed the First Officer to accomplish the QRH fumes removal checklist and the QRH overweight landing checklist. I communicated with the flight attendants the nature of the problem and gave them all the required and necessary information in order to prepare for our return back to ZZZ. Last but not least; I communicated with the passengers about our return and asked them to pay close attention to the instructions of the flight attendants. Both the First Officer and I completed all our checklists and landed back in ZZZ without further incidents. Once on the ground; the emergency vehicles were waiting for us and we asked them to do an inspection of the airplane after landing for anything abnormal like fumes; smoke; and fluids. The fire department personnel found nothing out of the ordinary from their visual inspection. We also realized that our symptoms felt better while using the oxygen masks. Once on the ground; we decided to take the O2 masks off because they make it rather difficult to communicate when they are being used; however; the jet exhaust smell was still present in the flight deck. We put the oxygen masks back on and used them all the way to the gate.Once at the gate and off the masks; both the First Officer and myself experienced the same symptoms of being light headed; woozy; metallic taste in mouth; and were extremely thirsty. I briefed the flight attendants and found out they all had the exact same symptoms. After deplaning the passengers; I requested medical care for the crew. The paramedics arrived at the gate and we were all examined. The lead had chest pains and was taken to the emergency room right away. For the rest of the crew and due to all our symptoms; I requested for all of us to be taken to the emergency room for further evaluation. Flight Attendant X and I were taken to [a nearby] hospital. The First Officer and the Flight Attendant Y were taken to a different hospital. At the end of all the testing and once the blood work analysis came back; both Flight Attendant X and I were diagnosed with low grade carbon monoxide poisoning and the Doctor kept us on oxygen for about 1 hour. We were then released from the hospital without further complications.I believe we did everything to the best of our abilities. I would suggest to brief the Fire Chief/Captain on our duties after an event like this one. At thegate; he was extremely abrasive and rather aggressive about getting us off the airplane to be looked at by the paramedics. I understand and appreciate his duties; however; I believe he is unaware of our duties and responsibilities after an event like this one and as the Pilot in Command; I expect the same respect from him as I give him and his crew.




Synopsis: Air carrier Captain reported persistent fumes resulting in health issues. After precautionary air return; flight crew was diagnosed with low grade carbon monoxide poisoning.