Shotgun metagenomics of dust microbiome from flight deck and cabin in civil aviation aircraft.

Microbial exposure is related to the health of passengers on commercial aircraft, but no studies characterized the microbial composition at the species level and identified their ecological determinants. We collected vacuum dust from floor and seat surfaces in flight decks and cabins of 18 aircraft, and amplification-free shotgun metagenomics was conducted to characterize the microbial composition. In total, 7437 microbial taxa were identified. The relative abundance for bacteria, eukaryote, viruses, and archaea was 96.9%, 1.8%, 0.3%, and 0.03%, respectively. The top bacterial species mainly derived from outdoor air and human skin included Sphingomonas, Corynebacterium, Micrococcus luteus, Variovorax paradoxus, Paracoccus dentrificans, and Propionibacterium acnes. The abundance of NIAID-defined pathogens was low, accounted for only 0.23% of total microbes. The microbial species and functional composition were structured by the indoor surface type (R2  = 0.38, Adonis), followed by the manufacturer of the aircraft (R2  = 0.12) and flight duration (R2  = 0.07). Indoor surfaces affected species derived from different habitats; the abundance of dry skin and desiccated species was higher on textile surfaces, whereas the abundance of moist and oily skin species was higher on leather surfaces. The growth rates for most microbes were stopped and almost stopped.

Musculoskeletal symptoms and psychosocial work environment, among Swedish commercial pilots.

PURPOSE: The associations between psychosocial work conditions and health in pilots are understudied, and therefore, the associations between the psychosocial work conditions and musculoskeletal problems among Swedish commercial pilots were investigated. METHODS: In 2010, a self-administered questionnaire study was performed among pilots in one Swedish commercial airline: 354 pilots participated (61 %). Musculoskeletal symptoms and the psychosocial work conditions measured by the demand control social support model were investigated. Odds ratios (OR) with 95 % confidence interval (95 % CI) were expressed per change of one unit on the interquartile score scale. RESULTS: Pilots on long-haul flights had less elbow symptoms (OR 0.34, 95 % CI 0.14-0.85), and women had more hand symptoms (OR 2.90, 95 % CI 1.11-7.52). There were associations between high work demands and symptoms from the neck (OR 2.04, 95 % CI 1.45-2.88), shoulders (OR 1.46, 95 % 1.05-2.03), elbows (OR 1.79, 95 % CI 1.10-2.90) and low back (OR 1.42, 95 % CI 1.02-1.96) in pilots. Low social support was associated with symptoms from the neck (OR 1.87, 95 % 1.35-2.58), shoulders (OR 1.56, 95 % CI 1.14-2.14) and low back (OR 1.63, 95 % CI 1.18-2.24). Low supervisor support was associated with neck (OR 1.67, 95 % CI 1.22-2.27), shoulders (OR 1.38, 95 % CI 1.02-1.87) and low back symptoms (OR 1.48, 95 % CI 1.09-2.01). The associations were mainly found among first officers. CONCLUSIONS: Musculoskeletal symptoms in pilots can be affected by poor psychosocial work conditions such as high demands and low social support, especially for first officers. The psychosocial aspects of organisational changes in commercial airlines should be taken into consideration.

Digestive functional symptoms among commercial pilots in relation to diet, insomnia, and lifestyle factors.

BACKGROUND: The aim of our study was to identify associations between digestive symptoms among pilots and diet, insomnia, and lifestyle factors. METHODS: A standardized questionnaire was mailed to all Stockholm pilots on duty in a Swedish airline company: 354 pilots and 564 office workers from the same company participated. Associations were analyzed by multiple logistic regressions with mutual adjustment. RESULTS: Of the pilots, 9.9% reported poor appetite, 15.2% heartburn, 12.4% diarrhea, 62.1% bloating, 9.3% constipation, and 14.4% epigastralgia. Pilots reported more bloating and poor appetite compared with office workers. The prevalence of insomnia was 70.6% among pilots and 63.1% among office workers. Among pilots, insomnia was related to poor appetite, heartburn, diarrhea, bloating, constipation, and epigastralgia. There were no associations between insomnia and digestive symptoms among office workers. Among pilots, higher body mass index (BMI) was related to heartburn and smokers more often suffered from constipation. Frequent milk consumption was associated with heartburn and less constipation; female pilots suffered from more constipation. The number of years as an active pilot was negatively associated with epigastralgia and bloating. CONCLUSION: Insomnia and some digestive symptoms were more common among pilots than office workers. In addition to insomnia, BMI, smoking, female gender, and milk consumption were associated with some digestive symptoms. The strong association between insomnia and digestive symptoms among pilots, but not among office workers, suggests a stress component related to this occupation.

Self-rated health (SRH), recovery from work, fatigue, and insomnia among commercial pilots concerning occupational and non-occupational factors.

Background: This study investigated associations of self-rated health (SRH), recovery from work, fatigue, and insomnia with working conditions, the psychosocial work environment, lifestyle, and sense of coherence (SOC) among commercial pilots. Methods: A standardized questionnaire was sent to all pilots in an airline company, of whom 354 (61%) responded. Associations were analyzed via ordinal and logistic regression with mutual adjustment. Results: Overall, 21.8% of participants reported low SRH, 13.0% reported not recovering from work during their free time, 61.9% experienced fatigue, and 70.6% experienced insomnia symptoms. A high level of demand at work was associated with poor SRH and more fatigue, and low social support at work was associated with insomnia and poorer recovery from work. Habits surrounding exercise and BMI were associated with SRH. Part-time pilots and captains reported experiencing better recovery from work than their counterparts, while female pilots and younger pilots reported less fatigue. Amount of free time after work and the type of airplane operated were associated with experience of insomnia symptoms. Finally, having a strong sense of coherence was protectively associated with all health outcomes. Conclusion: The psychosocial environment at work is essential for the health of pilots, and a strong sense of coherence can be protective. Occupational conditions may influence recovery from work, fatigue, and insomnia. Moreover, engaging in exercise, maintaining a healthy weight, working part-time, and having more free time after the working day could improve pilots' health.

Sleep problems and psychosocial work environment among Swedish commercial pilots.

BACKGROUND: The aim of this study was to assess relationships between sleeping problems and the psychosocial work situation based on the job-strain and iso-strain models among Swedish commercial pilots. METHODS: Three hundred fifty-four pilots participated (61%), who are in 2008 responded to a questionnaire concerning sleep problems, the psychosocial work situation, personal factors, and flight length. RESULTS: Low social support was associated with sleep problems for pilots. High demands were associated with sleep problems among captains and long-haul flights were associated with sleep problems among first officers. Low skill discretion was associated with less sleep problems among first officers. CONCLUSIONS: Psychosocial climate at work such as low social support affects negatively sleep for both captains and for first officers. More research on what creates a best social support for pilots and cabin crew is needed. Adjusting scheduling work crew teams could increase social support at work and contribute to a better sleep quality.

Organophosphates in aircraft cabin and cockpit air--method development and measurements of contaminants.

Methods for measurements and the potential for occupational exposure to organophosphates (OPs) originating from turbine and hydraulic oils among flying personnel in the aviation industry are described. Different sampling methods were applied, including active within-day methods for OPs and VOCs, newly developed passive long-term sample methods (deposition of OPs to wipe surface areas and to activated charcoal cloths), and measurements of OPs in high-efficiency particulate air (HEPA) recirculation filters (n = 6). In total, 95 and 72 within-day OP and VOC samples, respectively, have been collected during 47 flights in six different models of turbine jet engine, propeller and helicopter aircrafts (n = 40). In general, the OP air levels from the within-day samples were low. The most relevant OP in this regard originating from turbine and engine oils, tricresyl phosphate (TCP), was detected in only 4% of the samples (min-max

Hearing status among aircraft maintenance personnel in a commercial airline company.

The aim was to study subjective and objective hearing loss in a population of aircraft maintenance workers and identify predictors. A total of 327 aircraft maintenance personnel answered a self-administered work environment questionnaire (response rate 76%) and underwent audiometric test. The mean values for the hearing threshold at 3, 4, and 6 kHz for the ear with the most hearing loss were compared with a Swedish population database of persons not occupationally exposed to noise. Equivalent noise exposure during a working day was measured. Relationships between subjective and objective hearing loss and possible predictors (age, years of employment, self-reported exposure to solvents, blood pressure, and psycho-social factors) were analyzed by multiple logistic regression. At younger ages (<40 years), aircraft maintenance workers had higher hearing thresholds (1-3 dB) compared to the reference group, but such a difference was not found in older employees. Relationships were found between age and objective hearing loss, and between exposure to solvents and reported subjective hearing loss. Equivalent noise exposure during working days were 70-91 dB(A) with a maximal noise level of 119 dB(A). Aircraft maintenance workers are exposed to equivalent noise levels above the Swedish occupational standard, including some very high peak exposures. Younger employees have a higher age-matched hearing threshold level compared with a reference group. Thus, there is a need for further preventive measures.

Psychosocial work environment and medical symptoms among Swedish commercial airline cabin crew.

BACKGROUND: Associations between stress measured by the demands-control model, iso-strain model, and stress-related symptoms among cabin crew were studied. METHODS: A questionnaire about psychosocial work environment and symptoms was answered by 918 (82%) flight attendants, stewards, and pursers at one airline company in 2005. Adjustment was made for age, gender, smoking, job category, and flight length using multiple logistic regression. RESULTS: Weekly headaches, concentration difficulties, fatigue, and gastrointestinal symptoms were reported at rates of 18%, 10%, 56%, and 13%, respectively. Pursers scored higher on control than the others and they had lower associations between the strain measured by the demands-control model and symptoms than stewards and flight attendants. All symptoms were more common in the high strain situation than in the low strain (reference). An active situation was related to an excess of symptoms. Low social support in the iso-strain model increased risk of symptoms. CONCLUSIONS: Demands-control and iso-strain models are useful in studying stress-related symptoms in cabin crews. The dimension of social support adds explanatory value.

Hearing status among cabin crew in a Swedish commercial airline company.

PURPOSE: To study hearing loss in commercial airline cabin crew (CC). METHODS: Totally 155 male and 781 female CC (n = 936) in a Swedish airline company underwent repeated audiometric tests during 1974-2005. The last test was used to study hearing loss. The mean test values at 3, 4, 6 kHz were used for the ear with worse hearing loss. Data were compared with a Swedish population (n = 603) who were not occupationally exposed to noise. Equivalent noise levels (Leq) were measured in different aircraft. RESULTS: Leq was 78-84 dB (A), maximum A-weighted exposure was 114 dB. Median values for all ages were close to the reference group. No association was found between years of employment and hearing loss, when adjusting for age and gender by multiple logistic regression analysis. CONCLUSION: Cabin crew are exposed to equivalent noise levels below the current Swedish occupational standard, and have normal age-matched hearing threshold levels.

Tinnitus among airline pilots: prevalence and effects of age, flight experience, and other noise.

INTRODUCTION: Frequent or constant tinnitus can be a problem for pilots because it can be distracting and/or interfere with communications in the cockpit. We studied tinnitus in a population of airline pilots to determine its prevalence and identify predictors. METHODS: A total of 418 male and 42 female pilots on duty in a Swedish airline returned a completed tinnitus questionnaire (response rate 79%). Multiple logistic regression analysis was performed; variables retained in the model included age, smoking, exposure to loud impulse noise during leisure time, previous work as a military pilot, years of employment as a commercial pilot, and type of aircraft. When available, the pilots' most recent routine audiometric test (N = 388) was used to study the association between hearing impairment and tinnitus. RESULTS: A total of 40% of respondents had experienced tinnitus for more than 5 min during the past year, 18% reported constant or severe tinnitus, and 12% had at some time visited a doctor for problems related to tinnitus. There were associations between tinnitus and age, impulse noise, and hearing impairment at 3, 4, and 6 kHz. There was no association with aircraft type or work as a military pilot. Pilots with tinnitus were more likely to report themselves disturbed by noise in the cockpit. CONCLUSION: These results show that tinnitus is relatively common among pilots and can create problems with sensitivity to noise. The frequency of tinnitus is most closely related to age, gender, exposure to high impulse noise during leisure time, and hearing impairment.

Hearing status among commercial pilots in a Swedish airline company.

The aim was to study hearing impairment in commercial pilots. A total of 634 male and 30 female pilots (N=664) in a Swedish airline company underwent repeated audiological tests during the period 1974-2005. The last test was used to study hearing impairment. The mean values for the hearing test at 3, 4, and 6 kHz were used for the ear with worse hearing impairment. Data was compared with a general adult Swedish population (n=603) not occupationally exposed to noise. Equivalent noise levels gate to gate (Leq) were measured in the cockpit of different aircraft. Leq was 75-81 dB (A), peak exposures were 105 dB (A) from the cabin call signal. Median values were similar as in the reference group at all ages. There was no association between years of employment, tobacco smoking, and hearing impairment, when adjusted for age and gender by multiple logistic regressions analysis. In conclusion, pilots are exposed to equivalent noise levels below the current Swedish occupational standard of 85 dB (A), with short peak exposures above the standard, and have normal age-matched hearing thresholds.

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

OBJECTIVE: This study evaluates the influence of air humidification in aircraft on symptoms, tear-film stability, nasal patency, and peak expiratory flow. METHODS: Commercial air crew (N=71) were given a medical examination during eight flights from Stockholm to Chicago and eight flights in the opposite direction. Examinations were done onboard one Boeing 767 aircraft equipped with an evaporation humidifier in the forward part of the cabin. The investigators followed the air crew, staying one night in Chicago and returning with the same crew. Four of the flights had the air humidification device active in-flight to Chicago and deactivated when returning to Stockholm. The other four flights had the inverse humidification sequence. The humidification sequence was randomized and double blind. Hygienic measurements were performed. RESULTS: The humidification increased the relative air humidity by 10% in the 1st row in business class, by 3% in the last row (39th row) in tourist class, and by 3% in the cockpit. Air humidification increased tear-film stability and nasal patency and decreased ocular, nasal, and dermal symptoms and headache. The mean concentration of viable bacteria [77-108 colony-forming units (cfu)/m(3)], viable molds (74-84 cfu/m(3)), and particulate matter (1-8 microg/m(3)) was low, both during the humidified and non-humidified flights. CONCLUSIONS: Relative air humidity is low (10-12%) during intercontinental flights and can be increased by the use of a ceramic evaporation humidifier, without any measurable increase of microorganisms in cabin air. Air humidification could increase passenger and crew comfort by increasing tear-film stability and nasal patency and reducing various symptoms.

Perception of cockpit environment among pilots on commercial aircraft.

UNLABELLED: Impaired cockpit environment may influence both well-being and performance of pilots. OBJECTIVE: To study the perception of cockpit environment among pilots, in relation to demographic factors, and type of aircraft (B767-300, B737-600, DC9/21-41, MD 81/90 series). METHODS: A standardized questionnaire was mailed to all pilots in one airline company; 81% participated (n = 622). All flights were non-smoking flights and the B767 was the only aircraft operated on intercontinental flights. The DC9 was the only aircraft without air recirculation. Multiple logistic regression analysis was applied, controlling for age, gender, smoking, perceived psychosocial work environment, and type of aircraft. RESULTS: Younger age and a history of atopy and stress due to excess work were the main predictors of symptom and environmental perceptions. The most common symptoms were fatigue (14%), facial dermal (10%), and nasal symptoms (9%). Common complaints on cockpit environment were dry air (53%), dust and dirt (48%), noise (46%), and inadequate illumination (34%). Using the DC9 as a reference category, Boeing 767 pilots had more fatigue (OR 19.5; p < 0.001), throat symptoms (OR = 4.40; p < 0.05), complaints on dry air (OR = 2.93; p < 0.01), stuffy air (OR = 4.60; p < 0.01), static electricity (OR = 6.39; < 0.05), and dust (OR = 2.01; p < 0.05). Boeing 737 pilots had more complaints on noise (OR = 4.01; p < 0.001) and dust (OR = 1.81; p < 0.05). MD 81/90 pilots had more complaints on dry air (OR = 1.76; p < 0.05), dust (OR = 1.92; p < 0.05), and inadequate illumination (OR = 2.08; p < 0.05). CONCLUSION: Complaints on the cockpit environment were common and differed between different types of aircraft. This indicates a need to optimize the cockpit environment, e.g., increase the cleaning and relative air humidity.

Respiratory Illness and Allergy Related to Work and Home Environment among Commercial Pilots.

The aim was to study associations between work and home environment and prevalence and incidence of respiratory health and a history of atopy in a 3-y cohort of commercial pilots. A questionnaire was mailed in 1997 to all pilots in a Scandinavian airline company (N = 622); 577 (93%) participated. The same questionnaire was sent to the participants 3 years later, 436 participated (76%). There were questions on asthma, respiratory symptoms and infections, allergies, the cabin environment, psychosocial environment and the home environment. Associations were analyzed by multiple logistic regression, calculating odds ratios (OR) with 95% confidence intervals (95%CI). The incidence of doctors' diagnosed asthma and atopy were 2.4 and 16.6 per 1000 person years, respectively. Pilots changing type of flight during follow-up got more airway infections (OR = 11.27; 95% CI 2.39-53.14). Those reporting decreased work control (OR = 1.85; 95% CI 1.03-3.31 for 1 unit change) and those with environmental tobacco smoke (ETS) at home (OR = 3.73; 95% CI 1.09-12.83) had a higher incidence of atopy during follow up. Dampness or mould at home was associated with a higher prevalence of asthma symptoms (OR = 3.55; 95% CI 1.43-8.82) and airway infections (OR = 3.12 95% CI 1.27-7.68). Window pane condensation in winter at home, reported at baseline, was associated with increased incidence of asthma symptoms (OR = 4.14; 95% CI 1.32-12.97) and pilots living in newer buildings at baseline had a higher incidence of airway infections (OR = 5.23; 95% CI 1.43-19.10). In conclusion, lack of work control and ETS at home can be a risk factors for development of allergic symptoms in pilots. Window pane condensation at home can be a risk factor for incidence of asthma symptoms. Dampness and mould at home can be a risk factor for prevalence of asthma symptoms and airway infections and living in newer buildings can be a risk factor for incidence of airway infections.

Medical symptoms among pilots associated with work and home environments: a 3-year cohort study.

OBJECTIVE: To study associations between the cockpit environment, psychosocial work environment, home environment, and medical symptoms in a cohort of commercial pilots followed over 3 yr. METHODS: A standardized questionnaire was mailed in February-March 1997 to all Stockholm-based pilots on duty in a Scandinavian flight company (N = 622); 577 (93%) participated. During this time smoking was allowed on long haul flights, but not on shorter flights. Smoking was prohibited on all flights after September 1997. The same questionnaire was sent to the cohort of 577 pilots in February-March 2000; 436 participated (76%). The questionnaire contained questions on symptoms, the psychosocial work environment, and the home environment. Associations were investigated using multiple logistic and ordinal regression. RESULTS: Symptoms were common, especially eye symptoms (38.5%), nose symptoms (39.9%), and tiredness (29.9%). Pilots exposed to environmental tobacco smoke (ETS) on long haul flights had more eye symptoms (odds ratio = 1.91) and tiredness (odds ratio = 2.73). These symptoms were reduced when no longer exposed to ETS. Those who started working on long haul flights developed more nose symptoms. Pilots reporting increased work demands developed more nose and dermal symptoms and tiredness and those with decreased work control developed more eye symptoms. Pilots living in new houses, multifamily houses, and in recently painted homes reported more symptoms. CONCLUSION: Eliminating ETS exposure on board reduced medical symptoms. Further work to reduce ETS exposure globally is needed. Psychosocial aspects of the work environment for commercial pilots should be considered, as well as the home environment.

Brominated flame retardant exposure of aircraft personnel.

The use of brominated flame retardants (BFRs) such as polybrominated diphenyl ethers (PBDEs) in aircraft is the result of high fire safety demands. Personnel working in or with aircraft might therefore be exposed to several BFRs. Previous studies have reported PBDE exposure in flight attendants and in passengers. One other group that may be subjected to significant BFR exposure via inhalation, are the aircraft maintenance workers. Personnel exposure both during flights and maintenance of aircraft, are investigated in the present study. Several BFRs were present in air and dust sampled during both the exposure scenarios; PBDEs, hexabromocyclododecane (HBCDD), decabromodiphenyl ethane (DBDPE) and 1,2-bis (2,4,6-tribromophenoxy) ethane. PBDEs were also analyzed in serum from pilots/cabin crew, maintenance workers and from a control group of individuals without any occupational aircraft exposure. Significantly higher concentrations of PBDEs were found in maintenance workers compared to pilots/cabin crew and control subjects with median total PBDE concentrations of 19, 6.8 and 6.6 pmol g(-1) lipids, respectively. Pilots and cabin crew had similar concentrations of most PBDEs as the control group, except for BDE-153 and BDE-154 which were significantly higher. Results indicate higher concentrations among some of the pilots compared to the cabin crew. It is however, evident that the cabin personnel have lower BFR exposures compared to maintenance workers that are exposed to such a degree that their blood levels are significantly different from the control group.

Furry pet allergens, fungal DNA and microbial volatile organic compounds (MVOCs) in the commercial aircraft cabin environment.

There has been concern about the cabin environment in commercial aircraft. We measured cat, dog and horse allergens and fungal DNA in cabin dust and microbial volatile organic compounds (MVOCs) in cabin air. Samples were collected from two European airline companies, one with cabins having textile seats (TSC) and the other with cabins having leather seats (LSC), 9 airplanes from each company. Dust was vacuumed from seats and floors in the flight deck and different parts of the cabin. Cat (Fel d1), dog (Can f1) and horse allergens (Equ cx) were analyzed by ELISA. Five sequences of fungal DNA were analyzed by quantitative PCR. MVOCs were sampled on charcoal tubes in 42 TSC flights, and 17 compounds were analyzed by gas chromatography mass spectrometry (GC-MS) with selective ion monitoring (SIM). MVOC levels were compared with levels in homes from Nordic countries. The weight of dust was 1.8 times larger in TSC cabins as compared to LSC cabins (p < 0.001). In cabins with textile seats, the geometric mean (GM) concentrations of Fel d1, Can f1 and Equ cx were 5359 ng g(-1), 6067 ng g(-1), and 13 703 ng g(-1) (GM) respectively. Levels of Fel d1, Can f1 and Equ cx were 50 times, 27 times and 75 times higher respectively, in TSC cabins as compared to LSC cabins (p < 0.001). GM levels of Aspergillus/Penicillium DNA, Aspergillus versicolor DNA, Stachybotrys chartarum DNA and Streptomyces DNA were all higher in TSC as compared to LSC (p < 0.05). The sum of MVOCs in cabin air (excluding butanols) was 3192 ng m(-3) (GM), 3.7 times higher than in homes (p < 0.001) and 2-methyl-1-butanol and 3-methyl-1-butanol concentrations were 15-17 times higher as compared to homes (p < 0.001). Concentrations of isobutanol, 1-butanol, dimethyldisulfide, 2-hexanone, 2-heptanone, 3-octanone, isobutyl acetate and ethyl-2-methylbutyrate were lower in cabin air as compared to homes (p < 0.05). In conclusion, textile seats are much more contaminated by pet allergens and fungal DNA than leather seats. The use of seats with smooth surfaces should be encouraged. The MVOC levels differed between cabin air and homes.