Risk factors, health risks, and risk management for aircraft personnel and frequent flyers

Health in the Skies: A Narrative Review of the Issues Faced by Commercial Airline Pilots

While the health of airline pilots is crucial to ensuring the safe travel of millions of people worldwide, they remain vulnerable to a variety of health challenges due to the nature of their job. The purpose of this narrative review is to provide a comprehensive summary of the most common health issues experienced by commercial airline pilots. By examining the published literature on this topic, we sought to identify areas where further research is needed to understand better the health risks associated with being a pilot and to develop effective interventions to address these risks. We also highlight how recent technological advances in digital health can be leveraged to conduct research into the potential usefulness of telehealth assessments for identifying occupational hazards in the aviation sector and providing targeted interventions. Overall, addressing the challenges of taking care of pilots' health and ensuring public safety will require a collaborative effort among airlines, governments, and regulators. Prioritizing pilot health and safety can actually improve profitability in the aviation sector by reducing costs associated with absenteeism, turnover, and accidents.

Day-to-day variation in sleep duration is associated with increased all-cause mortality

STUDY OBJECTIVES

There is a paucity of data on the association between day-to-day variation in sleep pattern and all-cause mortality. We aimed to investigate whether day-to-day variation in sleep duration and onset of sleep are associated with cardiovascular and all-cause mortality.

METHODS

We used data belonging to 388 unique patients from the Midlife in the United States 2 Biomarker study (2004-2009). Information on sleep onset, duration, and sleep-wake cycles was collected for 7 consecutive days using the Actiwatch device. Sleep irregularity was assessed using mean and standard deviations in sleep duration and time of onset of sleep over 7 days. Cox proportional regression analysis and the Fine and Gray subdistribution method were used with all-cause and cardiovascular mortality, respectively.

RESULTS

Over a median of 8.6 years of follow-up, 37 patients died, including 10 deaths resulting from cardiovascular causes. There was no statistically significant increase in cardiovascular mortality with variation in sleep duration in the highest vs the lowest tertile (hazard ratio, 4.00; 0.45-35.48; P = .21). However, increased all-cause mortality was seen in the highest vs the lowest tertile (hazard ratio, 3.99; 1.33-11.94; P = .01). Multivariable model adjusting for confounders had higher all-cause mortality with increased sleep duration variation in the highest vs the lowest tertile: hazard ratio, 4.85; 1.52-15.49; P < .01).

CONCLUSIONS

Day-to-day variation in sleep duration is associated with increased all-cause mortality but not cardiovascular mortality after adjusting for mean sleep duration, inflammation, diabetes, age, body mass index, renal function, and blood pressure. Irregularity in the onset of sleep is not associated with all-cause mortality or cardiovascular mortality.

CITATION

Katamreddy A, Uppal D, Ramani G, et al. Day-to-day variation in sleep duration is associated with increased all-cause mortality. J Clin Sleep Med. 2022;18(3):921-926.

Sleep Irregularity and Risk of Cardiovascular Events: The Multi-Ethnic Study of Atherosclerosis

BACKGROUND

The cardiovascular system exhibits strong circadian rhythms to maintain normal functioning. Irregular sleep schedules, characterized by high day-to-day variability in sleep duration or timing, represent possibly milder but much more common and chronic disruption of circadian rhythms in the general population than shift work.

OBJECTIVES

This study aimed to prospectively examine the association between sleep regularity and risk of cardiovascular disease (CVD).

METHODS

In MESA (Multi-Ethnic Study of Atherosclerosis), 1,992 participants free of CVD completed 7-day wrist actigraphy for sleep assessment from 2010 to 2013 and were prospectively followed through 2016. The study assessed sleep regularity using the SD of actigraphy-measured sleep duration and sleep-onset timing across 7 days. Incident CVD included nonfatal and fatal cardiovascular events. A Cox proportional hazards model was used to estimate hazard ratios (HRs) for incident CVD according to SD of sleep duration and timing, adjusted for traditional CVD risk factors (including CVD biomarkers) and other sleep-related factors (including average sleep duration).

RESULTS

During a median follow-up of 4.9 years, 111 participants developed CVD events. The multivariable-adjusted HRs (95% confidence intervals) for CVD across categories of sleep duration SD were 1.00 (reference) for ≤60 min, 1.09 (0.62 to 1.92) for 61 to 90 min, 1.59 (0.91 to 2.76) for 91 to 120 min, and 2.14 (1.24 to 3.68) for >120 min (p trend = 0.002). Similarly, compared with participants with a sleep timing SD ≤30 min, the HRs (95% confidence intervals) for CVD were 1.16 (0.64 to 2.13) for 31 to 60 min, 1.52 (0.81 to 2.88) for 61 to 90 min, and 2.11 (1.13 to 3.91) for >90 min (p trend = 0.002). Exclusion of current shift workers yielded similar results.

CONCLUSIONS

Irregular sleep duration and timing may be novel risk factors for CVD, independent of traditional CVD risk factors and sleep quantity and/or quality.

General and passenger-relevant factors of work-related musculoskeletal disorders (WMSDs) among Chinese female flight attendants

BACKGROUND

A high prevalence of work-related musculoskeletal disorders (WMSDs) has been reported among flight attendants. Identifying the root causes of these disorders may improve the health conditions of flight attendants and further improve flight safety and service quality.

OBJECTIVE

In this study, we aimed to identify WMSD risk factors for a specific population, namely Chinese female flight attendants.

METHODS

A two-stage survey including an online questionnaire (46 flight attendants) and a semi-structured interview (16 flight attendants) was used to assess the WMSDs of Chinese female flight attendants. Text analysis tools in NVivo 11 were used to identify the main concerns and risk factors for WMSDs of Chinese flight attendants.

RESULTS

In the online questionnaire, more than 86% of the participants reported discomfort in at least one body part. Biomechanical factors, work organizational factors, and psychosocial factors were reported by participants in this study. Chinese passengers were found to have an effect on WMSD development in Chinese flight attendants.

CONCLUSIONS

The results of this study suggested that WMSDs are severe problems among Chinese flight attendants. General factors as well as the passenger-relevant factor were identified as the most influential causes of WMSDs.

Occupational Risk Factors for Prostate Cancer: A Meta-analysis

Prostate cancer is the second most common cancer in men worldwide. There are many occupational factors that have been suggested to cause prostate cancer. Our aim was to evaluate the evidence for causality by a literature review of occupational factors. We searched literature in Medline and SCOPUS from 1966 to June 30, 2015 to identify occupational risk factors for prostate cancer. The following risk factors were selected: farmers/agricultural workers, pesticides - whole group, and separately organophosphate and organochlorine pesticides, carbamates and triazines, cadmium, chromium, cutting fluids, acrylonitrile, rubber manufacturing, whole body vibration, shift work, flight personnel, ionizing radiation, and occupational physical activity. For each factor a literature search was performed and presented as meta-analysis of relative risk and heterogeneity (Q and I2 index). A total of 168 original studies met the inclusion criteria with 90,688 prostate cancer cases. Significantly increased risks were observed for the following occupational exposures: pesticides (metaRR = 1.15, 95% confidence interval [CI] = 1.01-1.32; I2 = 84%), and specifically group of organochlorine pesticides (meta relative risk [metaRR] = 1.08, 95% CI = 1.03-1.14; I2 = 0%), chromium (metaRR = 1.19, 95% CI = 1.07-1.34; I2 = 31%), shift work (metaRR = 1.25, 95% CI = 1.05-1.49; I2 = 78%) and pilots (metaRR = 1.41, 95% CI = 1.02-1.94; I2 = 63%) and occupational physical activity in cohort studies (metaRR = 0.87, 95% CI = 0.81-0.94; I2 = 0%). The literature review supports a causal association for a few of the previously suggested factors.

Risk management of free radicals involved in air travel syndromes by antioxidants

Frequent air travelers and airplane pilots may develop various types of illnesses. The environmental risk factors associated with air travel syndromes (ATS) or air travel-related adverse health outcomes raised concerns and need to be assessed in the context of risk management and public health. Accordingly, the aim of the present review was to determine ATS, risk factors, and mechanisms underlying ATS using scientific data and information obtained from Medline, Toxline, and regulatory agencies. Additional information was also extracted from websites of organizations, such as the International Air Transport Association (IATA), International Association for Medical Assistance to Travelers (IAMAT), and International Civil Aviation Organization (ICAO). Air travelers are known to be exposed to environmental risk factors, including circadian rhythm disruption, poor cabin air quality, mental stress, high altitude conditions, hormonal dysregulation, physical inactivity, fatigue, biological infections, and alcoholic beverage consumption. Consequences of ATS attributed to air travel include sleep disturbances (e.g., insomnia), mental/physical stress, gastrointestinal disorders, respiratory diseases, circulatory-related dysfunction, such as cardiac arrest and thrombosis and, at worst, mechanical and terrorism-related airplane crashes. Thus safety measures in the cabin before or after takeoff are undertaken to prevent illnesses or accidents related to flight. In addition, airport quarantine systems are strongly recommended to prepare for any ultimate adverse circumstances. Routine monitoring of environmental risk factors also needs to be considered. Frequently, the mechanisms underlying these adverse manifestations involve free radical generation. Therefore, antioxidant supplementation may help to reduce or prevent adverse outcomes by mitigating health risk factors associated with free radical generation.

Incidence of cancer among licenced commercial pilots flying North Atlantic routes

BACKGROUND

To evaluate cancer incidence among licenced commercial pilots in association with cosmic radiation.

METHODS

Cohort study where ionizing radiation dose of cosmic radiation was estimated from airline data and software program and cancer incidence was obtained by record linkage with nation-wide cancer registry. All licenced commercial male airline pilots were followed from 1955 to 2015, ever or never employed at airline with international routes. Standardized incidence ratios were calculated and relative risk by Poisson regression, to examine exposure-response relation.

RESULTS

Eighty three cancers were registered compared with 92 expected; standardized incidence ratios were 0.90 (95% CI 0.71 to 1.11) for all cancers, 3.31 (95% CI 1.33 to 6.81) for malignant melanoma, and 2.49 (95% CI 1.69 to 3.54), for basal cell carcinoma of skin. The risk for all cancers, malignant melanoma, prostate cancer, basal cell carcinoma of skin, and basal cell carcinoma of trunk increased with an increase in number of employment years, cumulative air hours, total cumulative radiation dose, and cumulative radiation dose sustained up to age of 40 years. The relative risk for the highest exposure categories of cumulative radiation dose were 2.42 (95% CI 1.50 to 3.92) for all cancers, 2.57 (95% CI 1.18 to 5.56) for prostate cancer, 9.88 (95% CI 1.57 to 190.78) for malignant melanoma, 3.61 (95% CI 1.64 to 8.48) for all basal cell carcinoma, and 6.65 (95% CI 1.61 to 44.64) for basal cell carcinoma of trunk.

CONCLUSIONS

This study was underpowered to study brain cancer and leukaemia risk. Basal cell carcinoma of skin is radiation-related cancer, and may be attributed to cosmic radiation. Further studies are needed to clarify the risk of cancers in association with cosmic radiation, other workplace exposure, host factors, and leisure sun-exposure, as clothes, and glass in cockpit windows shield pilots from the most potent ultraviolet-radiation.

Cosmic radiation and cancer: is there a link?

Cosmic radiation can cause genetic and cytogenetic damage. Certain occupations including airline pilots and cabin crew are acknowledged to have a greater exposure to cosmic radiation. In a systematic search of MEDLINE, performed from 1990 to 2014, we analyzed clinical studies using the keywords: cosmic radiation, cancer, chromosome aberration, pilots and astronauts. Increased incidence of skin cancers among airline cabin crew has been reported in a number of studies and appears to be the most consistent finding. However, as with other cancers, it is unclear whether increased exposure to cosmic radiation is a factor in the increased incidence or whether this can be explained by lifestyle factors. Further research is needed to clarify the risk of cancer in relation to cosmic radiation.

Mortality from cancer and other causes in commercial airline crews: a joint analysis of cohorts from 10 countries

BACKGROUND

Commercial airline crew is one of the occupational groups with the highest exposures to ionising radiation. Crew members are also exposed to other physical risk factors and subject to potential disruption of circadian rhythms.

METHODS

This study analyses mortality in a pooled cohort of 93 771 crew members from 10 countries. The cohort was followed for a mean of 21.7 years (2.0 million person-years), during which 5508 deaths occurred.

RESULTS

The overall mortality was strongly reduced in male cockpit (SMR 0.56) and female cabin crews (SMR 0.73). The mortality from radiation-related cancers was also reduced in male cockpit crew (SMR 0.73), but not in female or male cabin crews (SMR 1.01 and 1.00, respectively). The mortality from female breast cancer (SMR 1.06), leukaemia and brain cancer was similar to that of the general population. The mortality from malignant melanoma was elevated, and significantly so in male cockpit crew (SMR 1.57). The mortality from cardiovascular diseases was strongly reduced (SMR 0.46). On the other hand, the mortality from aircraft accidents was exceedingly high (SMR 33.9), as was that from AIDS in male cabin crew (SMR 14.0).

CONCLUSIONS

This large study with highly complete follow-up shows a reduced overall mortality in male cockpit and female cabin crews, an increased mortality of aircraft accidents and an increased mortality in malignant skin melanoma in cockpit crew. Further analysis after longer follow-up is recommended.

International outbreak investigation of Salmonella Heidelberg associated with in-flight catering

Rapid and wide dispersal of passengers after flights makes investigation of flight-related outbreaks challenging. An outbreak of Salmonella Heidelberg was identified in a group of Irish travellers returning from Tanzania. Additional international cases sharing the same flight were identified. Our aim was to determine the source and potential vehicles of infection. Case-finding utilized information exchange using experts' communication networks and national surveillance systems. Demographic, clinical and food history information was collected. Twenty-five additional cases were identified from Ireland, The Netherlands, Norway, USA and Canada. We conducted a case-control study which indicated a significant association between illness and consumption of milk tart (OR 10.2) and an egg dish (OR 6) served on-board the flight. No food consumed before the flight was associated with illness. Cases from countries other than Ireland provided supplementary information that facilitated the identification of likely vehicles of infection. Timely, committed international collaboration is vital in such investigations.

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.

Surgical and medical emergencies on board European aircraft: a retrospective study of 10189 cases

Introduction

In-flight medical and surgical emergencies (IMEs) onboard commercial aircrafts occur quite commonly. However, little epidemiological research exists concerning these incidents.

Methods

Thirty-two European airlines were asked to provide anonymous data on medical flight reports of IMEs for the years 2002 to 2007. The total number of incidents was correlated to revenue passenger kilometers (rpk). Additionally, on-board births and deaths, flight diversions, flight routes (continental/intercontinental) and involvement of a physician or medical professional in providing therapy were analysed.

Results

Only four airlines, of which two participated in this study, were able to provide the necessary data. A total of 10,189 cases of IMEs were analysed. Syncope was the most common medical condition reported (5307 cases, 53.5%) followed by gastrointestinal disorders (926 cases, 8.9%) and cardiac conditions (509 cases, 4.9%). The most common surgical conditions were thrombosis (47 cases, 0.5%) and appendicitis (27 cases, 0.25%). In 2.8% of all IMEs, an aircraft diversion was performed. In 86% of cases, a physician or medical professional was involved in providing therapy. A mean (standard deviation) of 14 (+/- 2.3, 10.8 to 16.6 interquartile range) IMEs per billion rpk was calculated.

Conclusions

The study demonstrates that although aviation is regulated by a variety of national and international laws, standardised documentation of IMEs is inadequate and needs further development.