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OBJECTIVES: This study aimed to estimate the incidence of asthma and assess the association between job exposure matrix (N-JEM) assigned occupational exposure, self-reported occupational exposure to vapour, gas, dust and fumes (VGDF), mould, damages from moisture and cold, and new-onset asthma. We also aimed to assess the corresponding population attributable fraction (PAF) for ever exposure to VGDF. DESIGN: Longitudinal population-based respiratory health study. SETTING: Responders from the baseline Telemark Study in south-eastern Norway were followed up from 2013 to 2018. PARTICIPANTS: 7120 participants, aged 16-55, were followed during a 5-year period. MAIN OUTCOME MEASURES: New-onset asthma and its association with self-reported occupational exposure to VGDF, data from the N-JEM and self-reported workplace conditions were assessed using logistic regression adjusted for gender, age, smoking and body mass index. The PAF was calculated using the PUNAF command in STATA. RESULTS: There were 266 (3.7%) cases of new-onset asthma and an incidence density of 7.5 cases per 1000 person-years. A statistically significant association was found for ever exposed to VGDF with an OR of 1.49 (95% CI 1.15 to 1.94), weekly OR 2.00 (95% CI 1.29 to 3.11) and daily OR 2.46 (95% CI 1.39 to 4.35) exposure to VGDF. The corresponding PAF for ever exposed to VGDF was 17% (95% CI 5.4% to 27.8%) and the risk of asthma onset increased with frequent VGDF exposure, indicating a possible exposure-response relationship (p=0.002 for trend). The N-JEM exposure group, accidental peak exposure to irritants had an increased risk of new-onset asthma, OR 2.43 (95% CI 1.21 to 4.90). A significant association was also found for self-reported exposure to visible damages due to moisture 1.51 (95% CI 1.08 to 2.11), visible and smell of mould 1.88 (95% CI 1.32 to 2.68), 1.55 (95% CI 1.12 to 2.16) and cold environment 1.41 (95% CI 1.07 to 1.86). CONCLUSION: Participants had elevated ORs for asthma associated with self-reported and N-JEM-assigned exposures. A PAF of 17% indicates that work-related asthma is still common. The possible exposure-response relationship suggests that reducing occupational VGDF exposure frequency could prevent the onset of asthma.

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OBJECTIVES: This study aimed to characterise participants lost to follow-up and identify possible factors associated with non-participation in a prospective population-based study of respiratory health in Norway. We also aimed to analyse the impact of potentially biased risk estimates associated with a high proportion of non-responders. DESIGN: Prospective 5-year follow-up study. SETTING: Randomly selected inhabitants from the general population of Telemark County in south-eastern Norway were invited to fill in a postal questionnaire in 2013. Responders in 2013 were followed-up in 2018. PARTICIPANTS: 16 099 participants aged 16-50 years completed the baseline study. 7958 responded at the 5-year follow-up, while 7723 did not. MAIN OUTCOME MEASURES: χ2 test was performed to compare demographic and respiratory health-related characteristics between those who participated in 2018 and those who were lost to follow-up. Adjusted multivariable logistic regression models were used to assess the relationship between loss to follow-up, background variables, respiratory symptoms, occupational exposure and interactions, and to analyse whether loss to follow-up leads to biased risk estimates. RESULTS: 7723 (49%) participants were lost to follow-up. Loss to follow-up was significantly higher for male participants, those in the youngest age group (16-30 years), those in lowest education level category and among current smokers (all p<0.001). In multivariable logistic regression analysis, loss to follow-up was significantly associated with unemployment (OR 1.34, 95% CI 1.22 to 1.46), reduced work ability (1.48, 1.35 to 1.60), asthma (1.22, 1.10 to 1.35), being woken by chest tightness (1.22, 1.11 to 1.34) and chronic obstructive pulmonary disease (1.81, 1.30 to 2.52). Participants with more respiratory symptoms and exposure to vapour, gas, dust and fumes (VGDF) (1.07 to 1.00-1.15), low-molecular weight (LMW) agents (1.19, 1.00 to 1.41) and irritating agents (1.15, 1.05 to 1.26) were more likely to be lost to follow-up. We found no statistically significant association of wheezing and exposure to LMW agents for all participants at baseline (1.11, 0.90 to 1.36), responders in 2018 (1.12, 0.83 to 1.53) and those lost to follow-up (1.07, 0.81 to 1.42). CONCLUSION: The risk factors for loss to 5-year follow-up were comparable to those reported in other population-based studies and included younger age, male gender, current smoking, lower educational level and higher symptom prevalence and morbidity. We found that exposure to VGDF, irritating and LMW agents can be risk factors associated with loss to follow-up. Results suggest that loss to follow-up did not affect estimates of occupational exposure as a risk factor for respiratory symptoms.

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BACKGROUND: Abnormal excessive daytime sleepiness (EDS) has been reported worldwide, but too little is known about EDS and its determinants in Search and Rescue (SAR) populations. We aimed to determine the prevalence of abnormal EDS and contributing factors among Royal Norwegian Air Force (RNoAF) SAR helicopter personnel.METHODS: In this cross-sectional study, a total of N = 175 RNoAF SAR personnel completed an electronic survey including socio-demographic and lifestyle questions. The Epworth Sleepiness Scale (ESS) was used as both a continuous and categorical outcome variable to measure EDS.RESULTS: Abnormal EDS defined by ESS was found in 41% of the participants in this study. We observed no associations between socio-demographic and lifestyle factors and abnormal EDS in this study. DISCUSSION: There is a high prevalence of abnormal EDS in the current RNoAF SAR population. Despite this elevated level of fatigue, we did not find that the socio-demographic and lifestyle factors assessed in this study were associated with abnormal EDS in RNoAF SAR helicopter personnel. Also unusually, the study cohort did not demonstrate higher scores in factors found to change ESS scores in similar study populations (e.g., caffeine use, tobacco use, exercise level). Further research is required to investigate other factors (organizational, operational) that may be associated with abnormal EDS in this and other SAR populations.Akter R, Larose TL, Sandvik J, Fonne V, Meland A, Wagstaff AS. Excessive daytime sleepiness and associated factors in military search and rescue personnel. Aerosp Med Hum Perform. 2021; 92(12):975-979.

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BACKGROUND: The work schedules of airline crewmembers include extended workdays, compressed work periods, and limited time for recovery, which may lead to cardiovascular strain and fatigue. The aim of this study was to evaluate changes in heart rate variability (HRV) during work and sleep, and with respect to work characteristics and breaks.METHODS: We followed 49 airline crewmembers during four consecutive workdays of ≥39 h. Data included HRV measurements, a questionnaire, and sleep/work diaries. HRV parameters include root mean square of successive differences (RMSSD), standard deviation of the normal beat-to-beat differences (SDNN), and the low and high frequency ratio (LF/HF).RESULTS: The results indicate higher levels of cardiovascular strain on the 4th compared to the 1st workday, most prominent among cabin crewmembers. In this group, we observed indications of decreased cardiovascular strain by increasing duration of sleep, demonstrated by increased RMSSD (B = 2.7, 95% CI 1.6, 3.8) and SDNN (B = 4.4, 95% CI 3.0, 5.7), and decreased LF/HF (B = -0.2, 95% CI, -0.4,-0.01). Similarly, longer duration of breaks was associated with lower cardiovascular strain, indicated by increased RMSSD (B = 0.1, 95% CI 0.03, 0.1) and SDNN (B = 0.1, 95% CI 0.1, 0.1). Among pilots, increased LF/HF indicated higher cardiovascular strain in those who often or always reported of high workload (B = 4.3, 95% CI 2.3, 6.3; and B = 7.3, 95% CI 3.2, 11.4, respectively).DISCUSSION: The results support the contention that the studied work period increases cardiac strain among airline crew. Work characteristics, breaks, and sleep are associated with changes in HRV.Goffeng EM, Nordby K-C, Tarvainen M, Järvelin-Pasanen S, Wagstaff A, Skare Ø, Lie J-A. Cardiac autonomic activity in commercial aircrew during an actual flight duty period. Aerosp Med Hum Perform. 2019; 90(11):945-952.

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BACKGROUND: Airline crew are being exposed to extended workdays and compressed work periods, with quick returns between duties, implying a heightened physiological and psychological strain that may lead to sleep deprivation and fatigue. The aim of the study was assessment of the effect of an extended day of flight duty and a compressed work week with regard to recovery, cumulative fatigue, and neurobehavioral performance.METHODS: We followed 18 pilots and 41 cabin crewmembers during four consecutive days of flight duty, comprising a total of ≥ 39 h, where the first day was ≥ 10 h. Information on demographics, work characteristics, health status, and physical activity was collected at baseline. Subjects completed logs for the first and fourth workday, including the Samn-Perelli Fatigue Checklist at three time points during these workdays. Two computer-based neurobehavioral tests were completed the evening prior to the first shift, and after the first and the fourth day of the work period.RESULTS: Number of flight sectors during the work period was 10-20. Self-reported fatigue levels increased during the workdays. Neurobehavioral test-scores did not deteriorate. The effects of each additional flight sector during the work period was elevated reaction times (RT) both among cabin crewmembers (B = 5.05 ms, 95% CI 0.6, 9.5) and pilots (B = 4.95 ms, 95% CI 0.4, 9.5). Precision was unaffected.DISCUSSION: Airline pilots and cabin crewmembers seem to obtain satisfactory sleep before and during the period of 4 consecutive days. The association between multiple flight sectors and increased fatigue supports previous findings.Goffeng EM, Wagstaff A, Nordby K-C, Meland A, Goffeng LO, Skare Ø, Lilja D, Lie J-AS. Risk of fatigue among airline crew during 4 consecutive days of flight duty. Aerosp Med Hum Perform. 2019; 90(5):466-474.

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The aim of this study was to investigate fluctuations in heart rate variability (HRV), which reflect autonomic nervous system (ANS) function and potential psychological and physical strain, among 24 health care workers during work and sleep during four consecutive extended work shifts. Data included 24/36/12 h of HRV measurements, two logbooks, and a questionnaire. A cross-shift/cross-week design was applied. HRV was measured during work, leisure time, and sleep. The HRV data included time-domain [mean RR, SD of normal to normal R-R intervals (SDNN), and root mean square of the successive differences (RMSSD)] and frequency-domain [low frequency (LF)/high frequency (HF) ratio] parameters. HRV parameters revealed significant differences among work, leisure time, and sleep. Mean RR, RMSSD, and SDNN values were lower and the LF/HF ratio was higher on the first versus last day of the work period; however, the differences were most prominent in the morning hours. The results indicate higher levels of cardiovascular stress on the first versus fourth day of the working period, and measurements at night indicate a satisfactory recovery from the extended shifts.

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BACKGROUND: The Swedish Air Force (SwAF) conducted a study in 2010 to harmonize portrayal of aeronautical info (AI) on SwAF charts with NATO standards. A mismatch was found concerning vertical obstructions (VO). Norway regarded Sweden's existing symbology as a way to solve the problem of overcrowded air charts and the two countries started to cooperate. The result of this development was a new set of symbology for obstacles. The aim of this study was to test the readability of the new obstacle and power line symbols compared to the old symbols. We also wished to assess the readability in NVG illumination conditions, particularly regarding the new symbols compared to the old. METHODS: In a randomized controlled study design, 21 volunteer military pilots from the Norwegian and Swedish Air Force were asked to perform tracking and chart-reading tests. The chart-reading test scored both errors and readability using a predefined score index. Subjective scoring was also done at the end of the test day. RESULTS: Overall response time improved by approximately 20% using the new symbology and error rate decreased by approximately 30-90% where statistically significant differences were found. DISCUSSION: The tracking test turned out to be too difficult due to several factors in the experimental design. Even though some caution should be shown in drawing conclusions from this study, the general trends seem well supported with the number of aircrew subjects we were able to recruit.Wagstaff AS, Larsen T. Readability of new aviation chart symbology in day and NVG reading conditions. Aerosp Med Hum Perform. 2017; 88(11):978-984.

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BACKGROUND: The aim of this study was to quantify causes of medical disqualification (groundings) of Norwegian commercial pilots for the period 2006-2010, and to compare our findings with former Norwegian studies on the subject to reveal possible changes in the disease spectrum over the last decades. We compared our data with previous studies for the periods 1982-1997 and 1997-2001, respectively. METHODS: The material was collected from the aeromedical section's archive. Files on all grounded pilots have been reviewed and classified by age group and diagnosis and grounding rates have been calculated. RESULTS: From the study population comprising 12,552 pilot-years for the years 2006-2010 inclusive, 85 pilots were permanently grounded, i.e., an average grounding rate of 6.8 per 1000 pilot-years. DISCUSSION: Compared with previous data there is a significant decrease in the disqualification rate due to cardiovascular conditions, while the disqualification rates due to ear, nose, and throat conditions and neurological conditions have both increased significantly.Høva JK, Thorheim L, Wagstaff AS. Medical reasons for loss of license in Norwegian professional pilots. Aerosp Med Hum Perform. 2017; 88(2):146-149.

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BACKGROUND: A candidate with paraplegia contacted the Institute of Aviation Medicine, Oslo, requesting a medical examination and medical certification for flying back seat on an F-16 Fighting Falcon. Thorough aeromedical examinations, including specialist evaluations, were initiated for the final decision to be made. CASE REPORT: Almost 13 yr earlier the candidate had acquired spinal cord damage at neurological level L1 after falling 4 m (13 ft) from out of a window. The CT scans showed luxation of the 12th thoracic vertebra with fracture and dislocation of the 1st lumbar vertebra. He went for surgery, where fixation of the 12th thoracic vertebra to the 1st lumbar vertebra was performed. He developed syringomyelia 1 yr postoperatively and was re-operated on twice in the following years. He was now in a wheelchair, but engaged himself in several sport activities such as sledge-hockey and sit-skiing, participating in several Paralympics. DISCUSSION: With respect to the general principles of aviation medicine, several considerations had to be taken into account before a medical certification could be given. The risks associated with an F-16 flight in relationship to the candidate's general health and the fixation of his spinal cord had to be evaluated. Also, his ability to perform required tasks during the flight and in case of an emergency was an important issue discussed. Finally, the candidate's medical and physical condition should not present a considerable risk to flight safety. After extensive specialist consultations and in-depth discussions, the candidate was given medical certification to fly back seat in a F-16. Chahal-Kummen M, Strand T-E, Owe JO, Gulliksen E, Wagstaff AS. Aeromedical evaluation for an F-16 candidate with incomplete paraplegia. Aerosp Med Hum Perform. 2016; 87(11):968-971.

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Helicopter aircrew members engage in highly demanding cognitive tasks in an environment subject to whole-body vibration (WBV). Sometimes their actions may not be according to plan (e.g. action slips and lapses). This study used a Sustained Attention to Response Task (SART) to examine whether action slips were more frequent during exposure to WBV. Nineteen participants performed the SART in two blocks. In the WBV block participants were exposed to 17 Hz vertical WBV, which is typical of larger helicopter working environments. In the No-WBV block there was no WBV. There were more responses to the rare no-go digit 3 (i.e. action slips) in the WBV block, and participants responded faster in the WBV block. These results suggest that WBV influences response inhibition, and can induce impulsive responding. WBV may increase the likelihood of action slips, mainly due to failure of response inhibition.

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Objective: This study sought to determine if mindfulness training (MT) has a measurable impact on stress and attentional control as measured by objective physiological and psychological means. Background: Periods of persistent, intensive work demands are known to compromise recovery and attentional capacity. The effects of 4-month MT on salivary cortisol and performance on 2 computer-based cognitive tasks were tested on a military helicopter unit exposed to a prolonged period of high workload. Methods: MT participants were compared to a wait list control group on levels of saliva cortisol and performance on a go-no go test and a test of stimulus-driven attentional capture. Participants also reported mental demands on the go-no go test, time of wakeup, sleep duration, quality of sleep, outcome expectancies, physical activity level, self-perceived mindfulness, and symptoms of depression and anxiety. Results: The results from a mixed between-within analysis revealed that the MT participants compared to the control group had a larger pre to post increase in high- and low-cortisol slopes, and decrease in perceived mental demand imposed by the go-no go test. Conclusion: MT alleviates some of the physiological stress response and the subjective mental demands of challenging tasks in a military helicopter unit during a period of high workload.

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INTRODUCTION: Neck pain in fighter pilots has been studied by several air forces and found to be relatively common. The aim of this project was to study the incidence, characteristics, possible associated causative factors, and operational impact of neck pain in Royal Norwegian Air Force (RNoAF) fighter pilots. METHODS: The study was designed as a retrospective anonymous questionnaire survey, collecting data on age, aircraft type, flying hours, and physical activity. Any experience of spinal symptoms related to flying was included, as well as detailed questions on operational factors. Estimates regarding how neck symptoms influenced flying performance were established using visual analogue scales (VAS). Pilots also described their own in-flight techniques to avoid neck symptoms. RESULTS: Of respondents, 72% had experienced neck pain in relation to flying, while 35% had experienced back pain. Of these episodes, 93% were related to neck rotation. Mean G level for acute incidents of in-flight pain was 6.7 G. Total training time is on average higher in pilots who have no neck pain compared to those who have had neck pain events in the last 12 mo; the mean training time being 3.9 h in the "no pain-group" vs. 2.7 h in the "pain group". "Checking six" was the most affected in-flight function. DISCUSSION: New technologies such as night-vision goggles and helmet-mounted displays increase helmet weight, thereby adding a higher strain to the neck even in moderate G environments. More research on specific prevention strategies is warranted in order to improve the in-flight working environment of fighter pilots.

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INTRODUCTION: Helicopter pilots are exposed to whole body vibration and noise in their working environment. Some researchers have found that kinetic energy from both noise and vibration is believed to affect pericardial thickness and lead to pulmonary fibrosis, known as vibroacoustic disease. The aim of this project was to determine whether we could discover similar findings in a selection of helicopter pilots. METHODS: A case control study where 27 helicopter pilots were compared to an age-matched control group of typical office workers was conducted. High resolution CT scanning of the thorax was used as the diagnostic method. Two medical radiologists interpreted the images independently, blinded to whether the subjects were pilots or from the control group. RESULTS: There were no signs of pericardial thickening or significant lung fibrosis formations in either of the groups. The average pericardium thickness for the helicopter group was 1.38 mm, SD = 0.54 mm, and for the control group: 1.37 mm, SD = 0.33 mm. There was no significant correlation between pericardium thickness and flight hours or age. DISCUSSION: The average pericardial thickness values for the helicopter and the age-matched control groups were almost identical. The results are within normal limits and comparable to an American study where 21 normal individuals were measured to 1.2 mm +/- 0.8 mm in an average of 26 different points by using trans-esophageal echocardiography. CONCLUSION: On the basis of the CT scans, our findings do not support the existence of vibroacoustic disease, where pericardial thickening is the most prominent sign.

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INTRODUCTION: Most helicopter operations are carried out at altitudes below 10,000 ft. At these altitudes, the risk of the crew experiencing hypoxia is low. For that reason, supplementary oxygen is not standard equipment on board most helicopters. Due to developments in military missions, high-altitude operations have become more frequent-as have the chances of the crew experiencing hypoxia. Helicopter crews are subjected to a higher load of whole-body vibration compared to fixed-wing aircraft crews. Whole-body vibration increases muscle work, with increased oxygen consumption as a result. We hypothesized that whole-body vibration, as experienced by helicopter crews, causes additional lowering of arterial oxygen levels under hypoxic conditions. METHODS: Data were collected from 10 subjects. They were all exposed to six different pressure altitudes in a hypobaric chamber, ranging from 1000 ft to 16,000 ft (approximately 305 m to approximately 4877 m). Arterial blood samples were drawn on two occasions at each altitude: after 14 min of rest and followed by 15 min of whole-body vibration (17 Hz, at 1.1 m x s(-2) in the z-axis) at each altitude. RESULTS: There was no significant effect of whole-body vibration on arterial oxygen pressure at altitudes up to 16,000 ft (approximately 4877 m), nor was there any effect on ventilation, seen as changes in arterial pressure of CO2. DISCUSSION: We contribute the lack of effect to the low vibration intensity used in this study. Since this vibration intensity was higher than experienced by helicopter crews during flight, we conclude that whole-body vibration does not contribute to hypoxia during high-altitude operations in helicopters.

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INTRODUCTION: Helicopter pilots are exposed to whole body vibration (WBV) in their working environment. WBV has been associated with low back pain (LBP) and helicopter pilots have a high prevalence for LBP compared with other professions. The aim of this study was to develop a test protocol for measuring helicopters with ISO 2631-1 and to perform a whole body vibration risk assessment based on the European Vibration Directive in a number of commonly used military and civilian helicopters. Both absolute values and individual difference in current helicopter types are of interest in order to evaluate the possible role of vibration in LBP in helicopter pilots. METHODS: In operationally relevant maneuvers, six helicopters were tested. In order to standardize measurements, each continuous flight was split into 15 separate maneuvers. A model of a working day exposure pattern was used to calculate A(8) vibration magnitudes for each helicopter. RESULTS: The vibration A(8) exposure estimates ranged from 0.32-0.51 m x s(-2) during an 8-h working day A(8). This compares with EU and ISO lower bounds risk criteria of 0.5 and 0.43 m x s(-2) A(8), respectively. DISCUSSION: Despite the vibration levels being relatively low, helicopter pilots report a high incidence of LBP. It is possible that helicopter pilot postures increase the risk of LBP when combined with WBV. The test protocol used in this study could be generally applied for other rotary winged aircraft testing to allow for comparison of WBV results. Data from different flight phases could be used to model different exposure profiles.

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OBJECTIVE: In order to devise effective preventive strategies, it is important to study workplace stressors that might increase the risk of workplace accidents - both affecting workers themselves as well as causing harm to third-parties. The aim of this report is to provide a systematic, updated overview and scientific review of empirical research regarding accidents in relation to long work hours and shift work, primarily based on epidemiological studies. METHODS: The search for articles was part of a large review study on the effects of work hours on various health outcomes, safety, and performance. The search strategy included 5 international scientific databases, and nearly 7000 articles were initially identified using our search string. Following the application of inclusion and exclusion criteria, 443 publications were found and evaluated using a pre-defined scoring system. Of these, 43 concerned safety and accidents but only 14 were considered to be of high quality (total score 2 or 3 on a scale from 0-3) and therefore used for this study. RESULTS: Both shift work and long working hours present a substantial and well-documented detrimental effect on safety - all the studies that are included in this review have one or more significant findings in this respect. The trends are quite coherent although the increases in accident rates are mostly from 50% to 100%. In epidemiological terms, this may be seen as rather small differences. The use of such data is therefore only of importance if the accident incidence is high or if accidents may have large effects. CONCLUSIONS: The findings are most relevant to safety-critical activities such as the transport and health sectors. Work periods >8 hours carry an increased risk of accidents that cumulates, so that the increased risk of accidents at around 12 hours is twice the risk at 8 hours. Shift work including nights carries a substantial increased risk of accidents, whereas "pure" night work may bring some protection against this effect due to resynchronization. The evaluated studies give no clear indications of any age or gender being specifically susceptible or protected against the effects of work times scheduling on accident risk.

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INTRODUCTION: In order to investigate possible hearing loss as a consequence of aviation noise, a comparative analysis of audiometric data from Norwegian Air Traffic Control (ATC) personnel, airline (fixed-wing) pilots, and helicopter pilots was performed. The results may be of use in giving advice regarding preventive measures. METHODS: Male ATC, airline, and helicopter pilots were selected randomly from the Civil Aviation Authority (CAA) medical files. There were 182 subjects included in the study: 50, 81, and 51 subjects for ATC, helicopter, and airline pilots, respectively. Two audiograms with a 2-3-yr interval were analyzed for each individual. Age correction was performed using data from ISO 7129. Threshold changes per year for the frequencies 3, 4, and 6 kHz were examined in particular after age correction. RESULTS AND DISCUSSION: For all three groups, mean hearing threshold levels were above (worse than) ISO 7129 predictions for most frequencies. As expected, hearing thresholds increased with age in the group as a whole. Looking at the 3-, 4-, and 6-kHz frequencies in particular, all groups had small but highly significant increases in hearing thresholds at 4 kHz between the first and second audiogram. CONCLUSIONS: The mean hearing thresholds for this group of aviation personnel are higher than International Standard ISO-7129 would predict according to age. Highly significant changes in hearing threshold after age correction, indicating possible noise-induced hearing loss, were found in all groups at 4 kHz. The fact that helicopter pilots had similar hearing loss to their other aviation colleagues indicates that current hearing protection for these pilots is effective in counteracting the increased noise levels in helicopters.

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Whole-body vibration and noise are inherent characteristics of helicopter operations. The helicopter pilot is affected by vibration from both low-frequency noise and mechanical vibration sources. The way this energy is transmitted to different tissues and organs depends on intensity, frequency and resonance phenomena within the body. Whole-body vibration is known to affect the muscular and skeletal system in the lower part of the spine, but less is known about the response at the cellular level to this stimulation. In some studies, chronic pathological changes have been described in different types of tissue in people exposed to low-frequency noise and vibration. The aim of the present study was to investigate possible cellular reactions to acute exposure to low-frequency noise and vibration in a helicopter. Thirteen healthy males aged 38 (18-69) years were subjected to a 3.5 h helicopter flight in a Westland Sea King Rescue helicopter. Blood tests taken before and after the flight were analysed for more than 40 parameters, including acute phase reactants, markers of leucocyte and platelet activation, complement and hemostasis markers, as well as a broad panel of cytokines, chemokines, growth factors and cell adhesion molecules. The subjects served as their own controls. With the exception of an increase in vascular cell adhesion molecule-1 (VCAM-1) during the flight, no statistically significant changes in the biomarkers were found after controlling for diurnal variation in the control blood tests, which were observed independently of the helicopter flight. In conclusion, one helicopter flight does not induce measurable changes in systemic biomarkers.

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BACKGROUND: The aim of this study is to present the reasons for medical disqualification (grounding) of Norwegian commercial pilots over a twenty-year period. We have also examined the issues of whether a change has taken place in the disease spectrum and to which extent new regulations have influenced aeromedical decision making. MATERIAL AND METHODS: The material is collected from the aeromedical section's archive. Files on all grounded pilots have been reviewed and classified by age group and diagnosis and grounding rates have been calculated. RESULTS: From the study population comprising 48,229 pilot-years, 275 pilots were permanently grounded, i.e. an average grounding rate of 5.7 per 1000 pilot-years. INTERPRETATION: Over this twenty-year period, the grounding rate based on cardiovascular disease fell; this may be explained by better treatment or more lenient requirements. In the diagnostic categories neurologic, musculoskeletal and psychiatric diseases the grounding rates went up. This cannot be attributed to more stringent health requirements, but possibly to the attitudes of pilots, who have become more critical of their working environment.

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INTRODUCTION: The medical requirements for commercial pilots are issued by the ICAO and the European aviation safety organization JAA. In Norway, the Aeromedical Section of the Civil Aviation Authority assesses whether pilots are medically fit to fly. This study presents the reasons for medical disqualification among the Norwegian commercial pilot population during a 20-yr period. METHODS: Files on all disqualified commercial pilots were reviewed and subdivided into age groups and diagnostic categories. Different disqualification rates were calculated. RESULTS: From the study population of 48,229 pilot-years, 275 pilots were permanently grounded, which gives a 20-yr average disqualification rate of 5.7 per 1,000 pilot-years. DISCUSSION AND CONCLUSIONS: For cardiovascular diseases the disqualification rate was lower after 1997 than before, which is explained by improved treatment and more lenient requirements. In the diagnostic categories, neurology, musculoskeletal, and psychiatric diseases, the disqualification rate increased after 1997. This fact is probably not attributed to more stringent health requirements, but possibly to the attitudes of the pilots, who have become more critical with respect to their subjective perception of their working environment and psychosocial factors.

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