Torsten Lindgren

Experimental exposure to propylene glycol mist in aviation emergency training: acute ocular and respiratory effects

OBJECTIVES Propylene glycol (PG) (1–2 propanediol; CAS No 57–55–6) is a low toxicity compound widely used as a food additive, in pharmaceutical preparations, in cosmetics, and in the workplace—for example, water based paints, de-icing fluids, and cooling liquids. Exposure to PG mist may occur from smoke generators in discotheques, theatres, and aviation emergency training. Propylene glycol may cause contact allergy, but there is sparse information on health effects from occupational exposure to PG. METHODS Non-asthmatic volunteers (n=27) were exposed in an aircraft simulator to PG mist over 1 minute, during realistic training conditions. Geometric mean concentration of PG was 309 mg/m3 (range 176–851 mg/m3), with the highest concentrations in the afternoon. The medical investigation was performed both before and after the exposure (within 15 minutes). It included an estimate of tear film stability break up time, nasal patency by acoustic rhinometry, dynamic spirometry, and a doctors administered questionnaire on symptoms. RESULTS After exposure to PG mist for 1 minute tear film stability decreased, ocular and throat symptoms increased, forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC) was slightly reduced, and self rated severity of dyspnoea was slightly increased. No effect was found for nasal patency, vital capacity (VC), FVC, nasal symptoms, dermal symptoms, smell of solvent, or any systemic symptoms. Those exposed to the higher concentrations in the afternoon had a more pronounced increase of throat symptoms, and a more pronounced decrease of tear film stability. In four subjects who reported development of irritative cough during exposure to PG, FEV1 was decreased by 5%, but FEV1 was unchanged among those who did not develop a cough. Those who developed a cough also had an increased perception of mild dyspnoea. CONCLUSION Short exposure to PG mist from artificial smoke generators may cause acute ocular and upper airway irritation in non-asthmatic subjects. A few may also react with cough and slight airway obstruction.

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 <LOQ-0.29 µg m(-3)). TCP was however detected in 39% of the wipe samples (n = 56) and in all HEPA-filters. Other OPs, as dibutylphenyl phosphate (DBPP) and tri-n-butyl phosphate (TnBP) originating from hydraulic oils were more prominent in the samples, illustrated by determination of TnBP in all of the within-day samples collected from airplanes (n = 76, min-max 0.02-4.1 µg m(-3)). All samples were collected under normal flight conditions. However, the TCP concentration during ground testing in an airplane that had experienced leakage of turbine oil with subsequent contamination of the cabin and cockpit air, was an order of magnitude higher as compared to after engine replacement (p = 0.02).

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 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.

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.

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.

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.

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.

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.

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.