Abstract
OBJECTIVE: To assess the contribution of secondhand smoke (SHS) to aircraft cabin air pollution and flight attendants' SHS exposure relative to the general population. METHODS: Published air quality measurements, modelling studies, and dosimetry studies were reviewed, analysed, and generalised. RESULTS: Flight attendants reported suffering greatly from SHS pollution on aircraft. Both government and airline sponsored studies concluded that SHS created an air pollution problem in aircraft cabins, while tobacco industry sponsored studies yielding similar data concluded that ventilation controlled SHS, and that SHS pollution levels were low. Between the time that non-smoking sections were established on US carriers in 1973, and the two hour US smoking ban in 1988, commercial aircraft ventilation rates had declined three times as fast as smoking prevalence. The aircraft cabin provided the least volume and lowest ventilation rate per smoker of any social venue, including stand up bars and smoking lounges, and afforded an abnormal respiratory environment. Personal monitors showed little difference in SHS exposures between flight attendants assigned to smoking sections and those assigned to non-smoking sections of aircraft cabins. CONCLUSIONS: In-flight air quality measurements in approximately 250 aircraft, generalised by models, indicate that when smoking was permitted aloft, 95% of the harmful respirable suspended particle (RSP) air pollution in the smoking sections and 85% of that in the non-smoking sections of aircraft cabins was caused by SHS. Typical levels of SHS-RSP on aircraft violated current (PM(2.5)) federal air quality standards approximately threefold for flight attendants, and exceeded SHS irritation thresholds by 10 to 100 times. From cotinine dosimetry, SHS exposure of typical flight attendants in aircraft cabins is estimated to have been >6-fold that of the average US worker and approximately 14-fold that of the average person. Thus, ventilation systems massively failed to control SHS air pollution in aircraft cabins. These results have implications for studies of the past and future health of flight attendants.