Does modern helicopter construction reduce noise exposure in helicopter rescue operations?

BACKGROUND: During helicopter rescue operations the medical personnel are at high risk for hearing damage by noise exposure. There are two important factors to be taken into account: first, the extreme variability, with some days involving no exposure but other days with extreme exposure; second, the extreme noise levels during work outside the helicopter, e.g. during winch operations. The benefit of modern, less noisier constructions and the consequences for noise protection are still unknown. OBJECTIVES: We estimated the noise exposure of the personnel for different helicopter types used during rescue operations in the Alps and in other regions of the world with special regard to the advanced types like Eurocopter EC 135 to compare the benefit of modern constructions for noise protection with earlier ones. METHODS: The rescue operations over 1 year of four rescue bases in the Alps (Raron and Zermatt in Switzerland; Landeck and Innsbruck in Austria, n = 2731) were analyzed for duration of rescue operations (noise exposure). Noise levels were measured during rescue operations at defined points inside and outside the different aircraft. The setting is according to the European standard (Richtlinie 2003/10/EG Amtsblatt) and to Class 1 DIN/IEC 651. With both data sets the equivalent noise level L(eq8h) was calculated. For comparison it was assumed that all rescue operations were performed with a specific type of helicopter. Then model calculations for noise exposure by different helicopter types, such as Alouette IIIb, Alouette II 'Lama', Ecureuil AS350, Bell UH1D, Eurocopter EC135, and others were performed. RESULTS AND CONCLUSIONS: Depending on modern technologies the situation for the personnel has been improved significantly. Nevertheless noise prevention, which includes noise intermissions in spare time, is essential. Medical checks of the crews by occupational medicine (e.g. 'G20' in Germany) are still mandatory.

[Practice of recognizing benzene-caused occupational diseases in 2006]. / Beurteilung myeloischer und lymphatischer Neoplasien bei beruflicher Benzolexposition. Anerkennungspraxis benzolbedingter Erkrankungen im Jahr 2006.

BACKGROUND AND PURPOSE: Benzene-caused hematologic diseases can be recognized as occupational diseases (ODs) if they fulfill the legal requirements specified under No. 1303 of the appendix of the German ordinance on ODs. The aim of this study is to analyze the most important criteria that determined whether these diseases were recognized or rejected as ODs according to No. 1303 in 2006. METHODS: In 2006, 70 suspected cases of OD No. 1303 reported in North Rhine-Westphalia were examined in terms of diagnosis, notifiers, cumulative benzene exposures, professions, coexposures, delays in notification, latency periods, interim periods, and recognition criteria. RESULTS: 70 benign and malignant diseases of myeloid and lymphoid origin were reported as suspected ODs, among them 41 B-cell non-Hodgkin's lymphomas (B-cell NHL). Latency periods ranged between 14 and 57 years (median 37; mean 36.3+/-11.4; n=45), estimated cumulative benzene exposures varied from 0 to 144 ppm-years (median 12; mean 11.4+/-22.8; n=59). Four of 70 suspected cases were recognized as OD No. 1303. In 37 cases (52.9%), the nature of the disease was assessed as being nontypical of OD No. 1303, in 50 cases (71.4%), no sufficient benzene exposure could be found. Mature-cell NHL and Hodgkin's lymphoma were not recognized as OD. Cumulative benzene exposures

Profiles of occupational exposure in patients with wood dust-induced nasal carcinoma.

OBJECTIVES: Regulations to certify nasal carcinoma as occupational disease induced by wood dust vary in the European countries. In Germany, it must be adenocarcinoma and the dust originating from beech or oak trees. In other countries, the disease is reconized as induced by occupation independent of the kind of wood dust or the type of carcinoma. With regard to the harmonization of regulations necessary in Europe we investigate whether these differences are acceptable from the scientific viewpoint. MATERIALS AND METHODS: In a retrospective analysis of a group of 28 patients with wood dust-induced nasal carcinoma in North Rhine-Westphalia, Germany, we studied whether significant differences in exposure, personal risks (smoking) and histological tumor type could justify the current German, Austrian and Luxembourg pattern of occupational disease certification. To quantify cumulative time of exposure we developed a new semiquantitative formula for the calculation of wood dust years (WDY). RESULTS: Our results indicate that there are no significant differences between the subgroups, i.e., exposure to hard wood (n = 13) or other woods (n = 15), WDY (13.1 +/- 11.3), smoking (n = 17) or nonsmoking, type of work and the diagnosis of nasal squamous cell carcinoma (n = 8) versus nasal adenocarcinoma (n = 20). The review of literature suggests systematic errors in the studies that led to the current German regulations. CONCLUSIONS: We recommend to amend the German, Austrian and Luxembourg regulations and to recognise nasal carcinomas as occupational disease, regardless of the type of wood dust exposure, and regardless of the tumor histology as also recommended by the International Agency for Research on Cancer (IARC).

Noise exposure during ambulance flights and repatriation operations.

OBJECTIVES: Although ambulance flights are routine work and thousands of employees work in repatriation organizations, there is no data on noise exposure which may be used for preventive advice. We investigated the noise exposure of crews working in ambulance flight organizations for international patient repatriation to get the data for specific guidelines concerning noise protection. MATERIAL AND METHODS: Noise levels inside Learjet 35A, the aircraft type which is most often used for repatriation operations, were collected from locations where flight crews typically spend their time. A sound level meter class 1 meeting the DIN IEC 651 requirements was used for noise measurements, but several factors during the real flight situations caused a measurement error of ~3%. Therefore, the results fulfill the specifications for class 2. The data was collected during several real repatriation operations and was combined with the flight data (hours per day) regarding the personnel to evaluate the occupationally encountered equivalent noise level according to DIN 45645-2. RESULTS AND CONCLUSIONS: The measured noise levels were safely just below the 85 dB(A) threshold and should not induce permanent threshold shifts, provided that additional high noise exposure by non-occupational or private activities was avoided. As the levels of the noise produced by the engines outside the cabin are significantly above the 85 dB(A) threshold, the doors of the aircraft must be kept closed while the engines are running, and any activity performed outside the aircraft - or with the doors opened while the engines are running - must be done with adequate noise protection. The new EU noise directive (2003/10/EG) states that protective equipment must be made available to the aircrew to protect their hearing, though its use is not mandatory.

[Paradigm change in the assessment of myeloid and lymphoid neoplasms associated with occupational benzene exposure]. / Paradigmenwechsel in der Beurteilung myeloischer und lymphatischer Neoplasien bei beruflicher Benzolexposition (BK-Ziffer 1303).

Benzene-caused hematologic neoplasms may be recognized as an occupational disease (OD) according to the German ordinance on ODs. At present, the OD No. 1303 covers heterogeneous diseases and various chemical agents triggering these diseases. The members of the medical advisory board specializing in ODs within the Ministry of Employment and Social Affairs recently proposed excluding "diseases of the blood, the hematopoietic and lymphatic system caused by benzene" from OD No. 1303 and classifying them as a separate OD. Benzene is generally acknowledged as a cause of acute myeloid leukemia, proven by numerous epidemiologic studies. However, there is less epidemiologic evidence of its association with other hematologic neoplasms, notably non-Hodgkin's lymphoma (NHL). To clarify this issue, the experts evaluated international literature and concluded that all kinds of myeloid and lymphoid malignancies including their prestages can be caused by occupational benzene exposure. Hence, physicians should ask patients about occupational benzene exposure and report any kind of diagnosed hematologic neoplasms, including their prestages, as suspected OD. The advisory board considered that a dose range starting from 10 ppm-years (cumulative benzene exposure) is sufficient for a > 50% probability of causing leukemias according to the WHO classification, including chronic lymphatic leukemia, and the potential preleukemias aplastic anemia and myelodysplastic syndrome, but excluding chronic myeloid leukemia (CML). For NHL and myeloproliferative diseases (including CML) the present epidemiologic evidence is considered not to be sufficient to describe a precise dose-effect relationship.

Cold exposure during helicopter rescue operations in the Western Alps.

OBJECTIVE: The study evaluates exposure to the cold of personnel involved in helicopter rescue operations in an alpine environment. METHODS: Rescue operations over a period of 15 months in the Oberwallis region (Switzerland) were analysed with special regard to the weather conditions, the locality and its altitude, and the duration. The equivalent chill temperature was estimated with two independent models. "Mean exposure" as well as the "worst-case situation" (based on maximum windspeed) were calculated. The results were evaluated according to the "classic" Siple-Passel model, the more recent model of Danielsson, ISO 11079, ISO 9920, the German industrial standard DIN 33403.5, and the German government regulations for work in cold environments ("G21"). RESULTS: The temperature models showed only marginal differences in chill temperature. Assuming "worst-case conditions", the Siple-Passel model showed that 87.1% of the operations occurred at chill temperatures > -30 degrees C, 12.1% in the range of -30 to -45 degrees C, and 0.8% at <-45 degrees C. The lowest temperature was -54.6 degrees C. The Danielson model resulted in 77.6% without the risk of frostbite, 20.1% with >5% risk, 6% with >50% risk and 1.8% with >95% risk. According to DIN 33403.5, 1.5% of the operations were performed at chill temperatures higher than cold class 1: 2.3% are class 1, 13.3% class 2, 34.7% class 3, 34.6% class 4 and 13.7% class 5. The maximum exposure times of DIN 33404.5 are exceeded in at least 0.5% of the missions. According to ISO 11079, clothing with 2.0 clo is sufficient in 40.2 and 23.9% of the operations [summer, required clothing insulation (IREQ) min. and IREQ neutr., respectively]. In winter the corresponding results are 0.3 and 0.0%. Duration of limited exposure is exceeded in 9.1 (IREQ min.) and 19.8% (IREQ neutr.) of the operations in summer and in 10.3 and 19.8% in winter. According to ISO 9920, ICL min. as well as ICL neutr. is exceeded in 100% in summer and winter operations. CONCLUSIONS: Alpine rescue operations are typical of a place of work in a cold--sometimes extremely cold--environment. Because of the limited time of exposure during the majority of the operations, the most important danger for rescue personnel is frostbite, although hypothermia cannot be excluded in cases of prolonged operations. Special advice to avoid the specific risks must be given to the crews and an examination by occupational medicine, e.g. according to "Working in cold environments, G21" of the German Berufsgenossenschaften, is recommended. Recommendations for adequate clothing are given.

Noise exposure during alpine helicopter rescue operations.

OBJECTIVES: We estimated the noise exposure of crews working in alpine helicopter rescue systems. METHODS: Noise levels of the the helicopters used (Alouette III, Alouette II 'Lama', Ecureuil and BK 117) were measured with a device according to class 2 DIN IEC 651. These data were combined with the flight data of the personnel to evaluate the equivalent noise level according to DIN 45645-2. RESULTS AND CONCLUSIONS: While the risk to patients should be limited to temporary threshold shifts the crew members are regularly exposed to equivalent noise levels of >85 dB(A) and, therefore, are at risk of permanent threshold shifts. Consequences for crew fitness to fly and for noise prevention (crew and patients) are discussed.