Commercial Fixed Wing
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Physiological - Other
Flight Deck / Cabin / Aircraft Event Illness / Injury
General Physical Injury / Incapacitation
Environment - Non Weather Related
First Officer (F/O) developed signs of hypoxia from mid cruise flight and verbalized his symptoms. I noticed pale skin; sweat and unsteady hands. I asked if he is fit to continue as pilot flying. He decided to surrender the pilot flying role. I decided against declaring pan pan since F/O's speech was clear at all times and his condition improved to normal during descent. The flight continued without further implications. I asked for self assessment after gate arrival. F/O decided to remove himself from the trip. Spokane had heavy smoke for the length of the layover. F/O ventilated smoke into his room during the night by having his wall unit air conditioning active. Dangerous air warnings were sent to all cell phones in Spokane in the early evening. Consider sending message to all crew members to stay indoors in affected areas and to turn wall air conditioning units off upon room arrival.
Air carrier Captain reported that the First Officer developed signs of hypoxia and noted that during the layover the area had experienced heavy smoke which had been drawn into the First Officer's hotel room through the air conditioning system.