Impact of Cabin Ozone Concentrations on Passenger Reported Symptoms in Commercial Aircraft

Abstract

Due to elevated ozone concentrations at high altitudes, the adverse effect of ozone on air quality, human perception and health may be more pronounced in aircraft cabins. The association between ozone and passenger-reported symptoms has not been investigated under real conditions since smoking was banned on aircraft and ozone converters became more common. Indoor environmental parameters were measured at cruising altitude on 83 US domestic and international flights. Passengers completed a questionnaire about symptoms and satisfaction with the indoor air quality. Average ozone concentrations were relatively low (median: 9.5 ppb). On thirteen flights (16%) ozone levels exceeded 60 ppb, while the highest peak level reached 256 ppb for a single flight. The most commonly reported symptoms were dry mouth or lips (26%), dry eyes (22.1%) and nasal stuffiness (18.9%). 46% of passengers reported at least one symptom related to the eyes or mouth. A third of the passengers reported at least one upper respiratory symptom. Using multivariate logistic (individual symptoms) and linear (aggregated continuous symptom variables) regression, ozone was consistently associated with symptoms related to the eyes and certain upper respiratory endpoints. A concentration-response relationship was observed for nasal stuffiness and eye and upper respiratory symptom indicators. Average ozone levels, as opposed to peak concentrations, exhibited slightly weaker associations. Medium and long duration flights were significantly associated with more symptoms compared to short flights. The relationship between ultrafine particles and ozone on flights without meal service was indicative of ozone-initiated chemistry.

Tropospheric Ozone Assessment Report: Tropospheric ozone from 1877 to 2016, observed levels, trends and uncertainties

“…Most passenger jet aircraft now have ozone destruction filters on the cabin air intakes, but not all, as avoidance is still an option. This is not always successful, however, as even these high limits are sometimes exceeded (Bekö et al, 2015). This urgent issue, combined with concern about adverse effects of aircraft exhaust emissions on the atmosphere, led to a collaboration between NASA and several US airlines to operate the Global Atmospheric Sampling Program (GASP).…”

Human symptom responses to bioeffluents, short-chain carbonyls/acids, and long-chain carbonyls in a simulated aircraft cabin environment

“…7, 29, 31 In particular, ozone by-products include creating or modifying carbonyls in the air of indoor settings in addition to the aircraft cabin that can be irritating and cause headaches, general malaise and lower a person’s ability to concentrate, which can be of concern to aircraft passengers. 6, 20, 32–34 While we incorporated several of these carbonyls in our evaluation, many additional compounds can be produced from ozone reactions. If properly maintained ozone scrubbers are not used, ozone levels in the aircraft cabin can be high when the flight paths are at high elevations (>10,000 m) or for planes flying at lower altitudes if stratospheric air penetrates into the troposphere.…”

“…Exposures to mixtures of volatile organic compounds (VOCs) have been associated with complaints about air quality, increased reports of transient symptoms and adverse health effects in enclosed environments, particularly aircraft cabins. [1][2][3][4] VOCs that off-gas from materials have often been reported as one culprit for poor air quality; 5 chemical reactions with ozone that enters from outdoors produce secondary pollutants that can be irritating; 6,7 and bioeffluent organic compounds emitted from people can result in perceived poor air quality and feelings of malaise. 8,9 Bioeffluent compounds include carbonyls, alkyl alcohols, aromatic alcohols, ammonia, and mercaptans.…”

“…[14][15][16][17] Surveys of crew members and passengers flying on planes have reported a variety of transient symptoms, such as ocular and respiratory irritation, headaches, fatigue, and dizziness. 6,16 In particular, the low RH typical of the aircraft cabin environment has been implicated in causing many of the transient symptoms reported. 8,18 However, controlled exposure studies that mimic some of the air quality and environmental conditions on aircraft have suggested that VOCs present in the aircraft cabin also contribute to the reported symptoms.…”

A case report of ocular chemical injury secondary to ozone gas

“…Many studies have shown the ozone exposure leading to lung damage and inflammation (Koren et al 1989;Cho et al 2001). There had been a questionnaire study on aircraft passengers, which showed a concentration-response relationship between maximum ozone concentration and reported eye symptoms encompassing watery eyes, itchy eyes, dry eyes, blurred, dim altered vision and eye pain (Beko et al 2015). Ozone was shown to destroy some constituent proteins found in human tears and this was determined quantitatively by radial immunodiffusion (Schmut et al 1994).…”