In recent years, there have been increasing complaints from cockpit crew, cabin crew, and passengers that the cabin air quality of commercial aircraft is deficient. A myriad of complaints including headache, fatigue, fever, and respiratory difficulties among many others have been registered, particularly by flight attendants on long-haul routes. There is also much concern today regarding the transmission of contagious disease inflight, particularly tuberculosis. The unanswered question is whether these complaints are really due to poor cabin air quality or to other factors inherent intlight such as lowered barometric pressure, hypoxia, low humidity, circadian dysynchrony, work/rest cycles, vibration, etc. This paper will review some aspects relevant to cabin air quality such as volatile organic compounds (VOCs), carbon dioxide (CO2), carbon monoxide (CO), ozone (O3), particulates, and microorganisms, as well as the cabin ventilation system, to discern possible causes and effects of illness contracted inflight. The paper will conclude with recommendations on how the issue of cabin air quality may be resolved.