Changes in the ocular and nasal signs and symptoms of aircrews in relation to the ban on smoking on intercontinental flights

Abstract

Objectives This study determined the influence of exposure to environmental tobacco smoke (ETS) in aircraft on measured and perceived cabin air quality (CAQ), symptoms, tear-film stability, nasal patency, and bioinarkers in nasal lavage fluid.Methods Commercial aircrews underwent a standardized examination, including acoustic rhinometry, nasal lavage, and measurement of tear-film break-up time. Eosinophilic cationic protein, myeloperoxidase, lysozyme, and albumin were analyzed in the nasal lavage fluid. Inflight investigations [participation rate 98% (N=39)] were performed on board 4 flights, 2 in each direction between Scandinavia and Japan. Scandinavian crew on 6 flights from Scandinavia to Japan participated in postflight measurements after landing [participation rate 85% (N=41)]. Half the flights permitted smoking on board, and the other half, 0.5 months later, did not. Hygienic measurements showed low relative air humidity on board (2-10%) and a carbon dioxide concentration of <I000 ppm during 99.6% of the cruising time. ResultsThe smoking ban caused a drastic reduction of respirable particles, from a mean of 66 (SD 56) pg/m3 to 3 (SD 0.8) yg/m3. The perceived CAQ was improved, and there were fewer symptoms, particularly ocular symptoms, headache and tiredness. Tear-film stability increased, and nasal patency was altered.C O~C~U S~O~S Despite a high air exchange rate and spatial separation between smokers and nonsmokers, smoking in commercial aircraft may cause significant air pollution, as indicated by a large increase in respirable particles. This ETS exposure is associated with an increase in ocular and general symptoms, decreased tear-film stability, and alterations of nasal patency.

The Effect of Flying and Low Humidity on the Admittance of the Tympanic Membrane and Middle Ear System

“…The bleed air from the engines of a modern jet, which is used to maintain cabin pressure, has a relative humidity of 0.5 to 1 % (Space et al 2000;Spengler and Wilson 2003), and most of the moisture within the cabin is provided by the passengers (Malmfors et al 1989;O'Donnell et al 1991), although there is also some moisture from galleys and toilets (O'Donnell et al 1991). At cruise altitudes, the cabin humidity depends on passenger load (Malmfors et al 1989;Arnold et al 2000) and is typically 5 to 20 %, but can be as low as 2 % (Backman and Haghighat 2000;Wieslander et al 2000). During take off and landing, the bleed air from the engines is shut off so that full power is available from the engines (Arnold et al 2000;Lindgren 2003); in these periods, 100 % of the cabin air is re-circulated, and the humidity is therefore higher than at cruise altitudes, but is still low.…”

“…At the end of a flight, particularly an international flight, most passengers and flight crew experience some effects of low humidity. Low humidity causes dryness of the throat (Wieslander et al 2000;Nadga and Koontz 2003) and dryness and discomfort of the eyes (Backman and Haghighat 2000). Moreover, low humidity leads to discomfort through drying of mucosa in the nose (Lee et al 2000;Space et al 2000).…”

Changes in ocular and nasal signs and symptoms among air crew in relation to air humidification on intercontinental flights

“…Acoustic rhinometry (Rhin 2000, SR Electronics, Lynge, Denmark) was performed at the end of the flight, the participant sitting after 5 minutes of rest, as previously described (9,(19)(20). The minimal cross-sectional areas (MCA) on each side of the nose were measured from 0 to 22 mm (MCA1) and from 23 to 54 mm (MCA2) from the nasal opening.…”

“…The longest exposure to dry air occurs during intercontinental flights, at cruising altitude (5). Previous studies of commercial aircrew have found a high prevalence of eye, nose, and throat symptoms (7)(8), attributed to environmental tobacco smoke (9) or ozone (8) in the cabin. These exposures are rare nowadays, since smoking is not allowed on board and ozone converters are common.…”

“…There may also be indirect negative health aspects of air humidification (17) that are related to microbial contamination in humidifiers (18). Recently, objective methods for studying environmental effects have been developed (9,(19)(20) for use in studying physiological affects on the nose (21) or eyes (9,16). In a recent air humidification study, an increase in relative air humidity from 35% to 43% caused a decrease in dermal symptoms but no detectable influence on the tear-film break-up time, nasal patency, or other symptoms Norbäck et al (11).…”