AbstractBecause of persistent complaints of ozone‐toxicity type symptoms among crew members of commercial airlines, we undertook a survey to determine the extent of the problem and the associated flight factors. Self‐reported questionnaires and flight diaries were completed by 1,330 flight attendants, (FAs) working for three different airlines. Ozone‐toxicity type symptoms were reported three or four times more frequently by FAs with airlines flying at high altitudes than by those with low‐flying airlines. When examined by characteristics of flights, the ozone‐toxicity type symptoms were significantly associated with flight altitude, duration and type of aircraft, but not with years worked, sex, medical history, or home residence. Other symptoms indicative of fatigue or stress were mainly associated with flight duration. While these indirect data cannot implicate ozone specifically, they offer evidence that ozone‐related health problems do exist among a large propor