Aircrew Exposure Research Articles

Radiation protection and estimate of commercial aircrew effective doses in Bosnia and Herzegovina.

Cosmic rays are the primary source of the daily exposure of aircrew and passengers to ionising radiation. This study aims to estimate the effective doses of ionising radiation for aircraft crews in Bosnia and Herzegovina by taking into consideration factors such as flight duration and altitude, as well as the geographical position of airports. The CARI-7 algorithm and neural network method were used in the analysis of data obtained from the Sarajevo International Airport. The results show that the estimated annual effective doses in 2021 range from 0.06 to 10mSv for flights to and from Belgrade and Dubai, respectively. Both linear regression and neural network models were developed to predict the effective dose based on flight duration, average altitude, latitude and maximum altitude. The findings reveal that flight duration is the most statistically significant factor, followed by average altitude, latitude and maximum altitude.

Information on cosmic radiation received by Belgian aircrew: a survey.

Exposure of aircrew to cosmic radiation had already been identified as an issue of concern in the European BSS of 1996 which requested airlines to assess the exposure of the crew and to inform their workers of the health risks their work involves. These requirements have been implemented in Belgian regulations in 2001 and updated with the transposition of the 2013/59/Euratom directive. Dosimetry data show that aircrew is the group of workers, which contributes the most to the collective dose of occupationally exposed workers in Belgium. In order to verify the extent of the information received by Belgian aircrew regarding their exposure to cosmic radiation, FANC, the Belgian radiation protection authority, launched in 2019 a large survey in collaboration with the Belgian Cockpit Association (BeCA), the professional association representing airline pilots in Belgium. The survey included 8 questions regarding the information of aircrew on cosmic radiation in general, on the individual dose level and on the risk related to exposure during pregnancy. A total of about 400 responses to the survey were received. Overall, the survey reveals that aircrew members in Belgium receive too little information about the potential risks, that they are not sufficiently informed about their own exposure and that female staff members are insufficiently informed about the hazards for the unborn child in case of pregnancy, and 66% of the respondents answered that their employer has never informed them about their exposure to cosmic radiation. However, most are aware of this phenomenon, either because they have looked up information or because they have discussed the topic with colleagues and professional associations. The results also showed that 17% of female crew continued to fly while being pregnant. Finally, the survey also allowed to identify differences and similarities between different groups of workers: cockpit and cabin crew, men and women. For instance, cabin crew was even less informed about their individual exposure than cockpit crew.

Radiation Risk Assessment Associated With Terrestrial Gamma Ray Flashes for Commercial Flights

AbstractTerrestrial gamma ray flashes (TGFs) are bursts of high‐energy photons produced in thunderstorms. Photons are produced by bremsstrahlung from high‐energy electrons, gaining energy through the electric field in the thunderstorm. Both electrons and photons are ionizing radiation and could have an impact on the radiation exposure of commercial aircrews and passengers. Previous works from Dwyer et al. (2010) and Pallu et al. (2021) have quantified doses possibly delivered by TGFs. They showed that the photon doses are sufficiently low so as not to be taken into account in the calculation of the radiation doses received during flights. However, electrons could deliver high doses up to 1 Sv, though in a compact area around the TGF source. In this work, we estimate an upper bound of the probability for a commercial flight to find itself in the electron beam of a TGF. Using the first Fermi‐Gamma ray Burst Monitor TGF catalog and both simulated routes between airports as a first step and real flight routes from Air France airline for 2.5 years as a second step, we show that the probability is lower than one aircraft hit every 2 years for the total air traffic. Knowing that we did not take into account altitudes and the fact that pilots usually avoid thunderstorms, it is likely that no aircraft would have been hit by the source of a TGF since the beginning of the commercial aviation.

Cosmic Radiation Exposure of Aircraft Crew under the Impact of Geomagnetic Vertical Cutoff Rigidity: Case Study of International Flights from Suvarnabhumi Airport, Thailand

Aircrew members are occupationally exposed to higher levels of galactic cosmic radiation than the general population in most parts of the world. The International Commission on Radiological Protection (ICRP) is concerned by the exposure of aircrews to cosmic radiation. The cosmic radiation intensity in the Earth atmosphere depends on many factors, e.g., the solar activity, altitude, and geomagnetic vertical cutoff rigidity on Earth. This study aimed to calculate the occupational radiation dose for aircraft crews during the solar minimum and maximum on fl ights from Suvarnabhumi Airport (BKK), Thailand, to 11 destinations worldwide. Based on the Monte Carlo simulation code of CARI-7 and JISCARD GUI, the cosmic radiation doses on fl ights was calculated. The maximum dose of a roundtrip fl ight (Bangkok–Helsinki) during the solar minimum condition was approximately 97.4 μSv (CARI-7) and 84.7 μSv (JISCARD GUI). The maximum radiation dose corresponded to 110 and 20 roundtrips for general aircraft crew and pregnant crew, respectively. This fi nding indicates that the polar-latitude region of Helsinki fl ights at low vertical cutoff rigidity ranges is of concern in terms of high-exposure cosmic radiation. The uncertainty associated with the result of the two codes was less than 30%. Therefore, the results were in reasonable agreement, and the codes could be used to calculate the exposure of aircraft crew to cosmic radiation.

Radiation in the Atmosphere—A Hazard to Aviation Safety?

Exposure of aircrew to cosmic radiation has been recognized as an occupational health risk for several decades. Based on the recommendations by the International Commission on Radiological Protection (ICRP), many countries and their aviation authorities, respectively have either stipulated legal radiation protection regulations, e.g., in the European Union or issued corresponding advisory circulars, e.g., in the United States of America. Additional sources of ionizing and non-ionizing radiation, e.g., due to weather phenomena have been identified and discussed in the scientific literature in recent years. This article gives an overview of the different generally recognized sources due to weather as well as space weather phenomena that contribute to radiation exposure in the atmosphere and the associated radiation effects that might pose a risk to aviation safety at large, including effects on human health and avionics. Furthermore, potential mitigation measures for several radiation sources and the prerequisites for their use are discussed.

A paradigm approach toward predicting barotrauma

Barotrauma is one of the most common medical problems associated with aviation and has been a causal factor for significant loss of trained aircrew hours. The occurrence of barotrauma has been reported not only in flight but also during simulated exposures to changing pressures as a part of aeromedical evaluation and training. This occurrence is despite the screening of individuals by otoscopy and tympanometry before exposure to barometric changes. In such cases, baro-challenge-induced eustachian tube (ET) dysfunction has been identified as the most probable cause, leading to decreased ability to equalize pressures across the middle ear. This paper describes a paradigm approach to the prediction of baro-challenge-induced ET dysfunction using the nine-step test and ET dysfunction questionnaire. The inclusion of the test as a screening tool before exposure of aircrew to baro-challenge after recovery from their ear, nose, and throat ailments is recommended to prevent occurrence/ reoccurrence of barotrauma.

Dose assessment of aircrew: the impact of the weighting factors according to ICRP 103

In their most recent recommendations, the International Commission on Radiological Protection (ICRP) proposed the use of a set of updated tissue and radiation weighting factors for the calculation of the effective dose. This recommendation was adopted in the European Union by the directive 2013/59/EURATOM in 2013 and implemented in the corresponding radiation protection regulations in Germany in 2018. In this study, we investigate the impact of the new weighting factors according to ICRP 103 on the dose rates of the effective dose due to the exposure of aircrew to cosmic radiation with the PANDOCA model for the description of the complex radiation field in the atmosphere. The application of the updated weighting factors leads to a reduction in the rate of the effective dose in the order of 20% to 30% depending on atmospheric and geomagnetic shielding as well as solar modulation.

Development of a multiaxis active seat mount to mitigate helicopter aircrew whole-body vibration exposure

This article presents the development and evaluation of a proof-of-concept multiaxis and actively controlled helicopter seat mount for aircrew whole-body vibration reduction. The multiaxis seat mount is designed to be installed between the helicopter seat floor and the seat supporting structure to minimize the impact on crashworthiness requirements of the helicopter seat. The design involves multiple miniature force actuators to counteract the vibrations of the seat frame and occupant transmitted from the helicopter floor in three orthogonal directions. The actuators are controlled by an adaptive feedforward filtered-x least mean square algorithm to cancel the helicopter floor vibration input. The prototype active seat mount design was tested in various configurations with a shaker table providing representative Bell-412 helicopter vibration inputs. Test results demonstrated that the vibrations of the seat frame and mannequin occupant body were suppressed simultaneously, and the major N/rev harmonic peaks of the occupant’s whole-body vibration were reduced by more than 20 dB. This demonstrated that the multiaxis active seat mount design can mitigate the whole-body vibration exposure of the helicopter aircrew to improve their ride quality and reduce adverse health effect.

Radiation exposure of aircrews due to Space Radiation

Space radiation mainly consists of trapped particles inside the Earth’s magnetosphere, galactic and solar cosmic rays. Cosmic rays propagating in the interplanetary medium, reach the top of the Earth’s atmosphere and collide with the molecules of the atmospheric layers creating showers of secondary particles that can be recorded by ground-based neutron monitors or muon detectors. Due to these cascades, the radiation environment in various atmospheric altitudes is entirely different than the one experienced on the Earth’s surface. Space radiation is ionizing (trapped particles, galactic and solar cosmic rays) as well as non-ionizing (ultra-violet radiation). It is known that ionizing radiation is very dangerous for all biological systems, causing a variety of acute and chronic effects. The determination of the occupational exposure of aircrews to space radiation is of great importance. DYnamic Atmospheric Shower Tracking Interactive Model Application (DYASTIMA), as well as its extension DYASTIMA-R, is a standalone application, based on the toolkit Geant4, that simulates the propagation of cosmic radiation into the atmosphere. DYASTIMA provides all the necessary information about the study of the cascade in different atmospheric altitudes, while DYASTIMA-R, as a dosimetry application, calculates radiobiological quantities, such as dose rate and equivalent dose rate for the determination of the exposure, based on the output provided by DYASTIMA. These quantities are calculated for solar minimum and solar maximum conditions. DYASTIMA can be accessed through the portals ofthe European Space Agency (ESA) (http://swe.ssa.esa.int/spaceradiation) and the Athens Neutron Monitor Station (A.Ne.Mo.S) (http://cosray.phys.uoa.gr/index.php/dyastima).

First Steps Toward the Verification of Models for the Assessment of the Radiation Exposure at Aviation Altitudes During Quiet Space Weather Conditions

AbstractSpace weather is an important driver of the exposure of aircrew and passengers to cosmic rays at flight altitudes, which has been a matter of concern for several decades. The assessment of the corresponding radiation doses can be realized by measurements or model calculations that cover the whole range of the radiation field in terms of geomagnetic shielding, atmospheric shielding, and the effects of space weather. Since the radiation field at aviation altitudes is very complex in terms of particle composition and energy distribution, the accurate experimental determination of doses at aviation altitudes is still a challenging task. Accordingly, the amount of data with comparatively small uncertainties is scarce. The Community Coordinated Modeling Center invited the Federal Aviation Administration, the German Aerospace Center, and the National Aeronautics and Space Administration to make their radiation models for aviation CARI‐7A, PANDOCA, and NAIRAS available for interested users via the Community Coordinated Modeling Center web site. A concomitant comparison of model calculations with measuring data provided information on the predicting capabilities and the uncertainties of the current versions of these models under quiet space weather conditions.

IN-FLIGHT EXPOSURE TO COSMIC RADIATION ALONG SOME COMMERCIAL AIRLINE ROUTES TO AND FROM NIGERIA

The study of “external” radiation called cosmic radiation that strikes the earth from anywhere beyond the atmosphere is of great importance in radiation protection. All human beings are exposed to an uncontrollable amount of cosmic radiation on the ground level. Those who travel in space, airline crews and frequent flyers are exposed to additional level of cosmic radiation during their trip but unfor-tunately many of them are not aware of this. This workcalculates the exposure of aircrews and fre-quent flyers to cosmic radiation during travel along some air routes to and from Nigeria. The effective dose was computed using a dedicated software CARI 6M, developed by US FAA.The study focuses on the significance of the in-flight exposure, assessment and estimation of in-flight exposure using the dedicated software and some ways of controlling the exposures so that airline crews and frequent flyers are not exposed to fatal levels of radiation.It was observed that the cosmic radiation doses re-ceived by passengers and crew members on board on flights from Lagos Nigeria to countries in Amer-ica were more than what they received en-route countries in Asia.

Assessment of the skin dose for aircrew

Epidemiological studies are a useful instrument for investigating the influence of environmental factors on human health. In this context, the determination and quantification of the corresponding exposure is a demanding challenge. With regard to the investigation of the potential health effects in aircrew due to cosmic radiation, their occupational exposure at aviation altitudes is usually assessed in terms of the radiation protection quantity effective dose, which is stored in and available from official dose registers in many countries. However, when biological effects on a particular organ are investigated, knowledge of the corresponding exposure of that particular organ is necessary. In this study, we investigate the differences between the skin dose and the effective dose for the exposure of aircrew to cosmic radiation using a mathematical model for the radiation field at aviation altitudes. Furthermore, we present a method to deduce skin dose values from the officially registered effective doses.

Assessment of spectral and angular characteristics of sub-GLE events using the global neutron monitor network

New recently installed high-altitude polar neutron monitors (NMs) have made the worldwide NM network more sensitive to strong solar energetic particle (SEP) events, registered at ground level, namely ground-level enhancement (GLE) events. The DOMC/B and South Pole NMs in addition to marginal cut-off rigidity also possess lower atmospheric cut-off compared to the sea level. As a result, the two high-altitude polar NM stations are able to detect lower energy SEP events, which most likely would not be registered by the other (near sea level) NMs. Here, we consider several candidates for such type of events called sub-GLEs. Using the worldwide NM database (NMDB) records and an optimization procedure combined with simulation of the global NM network response, we assess the spectral and angular characteristics of sub-GLE particles. With the estimated spectral characteristics as an input, we evaluate the effective dose rate in polar and sub-polar regions at typical commercial flight altitude. Hence, we demonstrate that the global NM network is a useful tool to estimate important space weather effects, e.g., the aircrew exposure due to cosmic rays of galactic and/or solar origins.

CONCORD: comparison of cosmic radiation detectors in the radiation field at aviation altitudes

Space weather can strongly affect the complex radiation field at aviation altitudes. The assessment of the corresponding radiation exposure of aircrew and passengers has been a challenging task as well as a legal obligation in the European Union for many years. The response of several radiation measuring instruments operated by different European research groups during joint measuring flights was investigated in the framework of the CONCORD (COmparisoN of COsmic Radiation Detectors) campaign in the radiation field at aviation altitudes. This cooperation offered the opportunity to measure under the same space weather conditions and contributed to an independent quality control among the participating groups. The CONCORD flight campaign was performed with the twin-jet research aircraft Dassault Falcon 20E operated by the flight facility Oberpfaffenhofen of the German Aerospace Center (Deutsches Zentrum fur Luft- und Raumfahrt, DLR). Dose rates were measured at four positions in the atmosphere in European airspace for about one hour at each position in order to obtain acceptable counting statistics. The analysis of the space weather situation during the measuring flights demonstrates that short-term solar activity did not affect the results which show a very good agreement between the readings of the instruments of the different institutes.

Measurement of dose equivalent distribution on-board commercial jet aircraft

The annual effective doses of aircrew members often exceed the limit of 1 mSv for the public due to the increased level of cosmic radiation at the flight altitudes, and thus, it is recommended to monitor them [International Commission on Radiation Protection. 1990 Recommendations of the International Commission on Radiological Protection. ICRP Publication 60. Ann. ICRP 21: (1-3), (1991)]. According to the Monte Carlo simulations [Battistoni, G., Ferrari, A., Pelliccioni, M. and Villari, R. Evaluation of the doses to aircrew members taking into consideration the aircraft structures. Adv. Space Res. 36: , 1645-1652 (2005) and Ferrari, A., Pelliccioni, M. and Villari, R. Evaluation of the influence of aircraft shielding on the aircrew exposure through an aircraft mathematical model. Radiat. Prot. Dosim. 108: (2), 91-105 (2004)], the ambient dose equivalent rate Ḣ*(10) depends on the location in the aircraft. The aim of this article is to experimentally evaluate Ḣ*(10) on-board selected types of aircraft. The authors found that Ḣ*(10) values are higher in the front and the back of the cabin and lesser in the middle of the cabin. Moreover, total dosimetry characteristics obtained in this way are in a reasonable agreement with other data, in particular with the above-mentioned simulations.

Occupational exposure of air crews to tricresyl phosphate isomers and organophosphate flame retardants after fume events

Aircraft cabin air can possibly be contaminated by tricresyl phosphates (TCP) from jet engine oils during fume events. o-TCP, a known neurotoxin, has been addressed to be an agent that might cause the symptoms reported by cabin crews after fume events. A total of 332 urine samples of pilots and cabin crew members in common passenger airplanes, who reported fume/odour during their last flight, were analysed for three isomers of tricresyl phosphate metabolites as well as dialkyl and diaryl phosphate metabolites of four flame retardants. None of the samples contained o-TCP metabolites above the limit of detection (LOD 0.5 μg/l). Only one sample contained metabolites of m- and p-tricresyl phosphates with levels near the LOD. Median metabolite levels of tributyl phosphate (TBP), tris-(2-chloroethyl) phosphate (TCEP) and triphenyl phosphate (TPP) (DBP 0.28 μg/l; BCEP 0.33 μg/l; DPP 1.1 μg/l) were found to be significantly higher than in unexposed persons from the general population. Median tris-(2-chloropropyl) phosphate (TCPP) metabolite levels were significantly not higher in air crews than in controls. Health complaints reported by air crews can hardly be addressed to o-TCP exposure in cabin air. Elevated metabolite levels for TBP, TCEP and TPP in air crews might occur due to traces of hydraulic fluid in cabin air (TBP, TPP) or due to release of commonly used flame retardants from the highly flame protected environment in the airplane. A slight occupational exposure of air crews to organophosphates was shown.

Aircrew Exposure to Handheld Laser Pointers: the Potential for Retinal Damage

Aviation authorities around the world continue to report substantial growth in the incidence of laser devices being aimed at aircraft in flight. Despite government restrictions, affordable handheld laser devices, with a power of up to several thousand mW, are now easily obtainable via the Internet. Lasers of this power output and wavelength have a nominal ocular hazard distance of around 1000 ft (304.8 m). Aviation medical specialists should be aware these lasers have the potential to cause retinal damage when aircrew operating at low altitudes are exposed.

Measuring cosmic-ray exposure in aircraft using real-time personal dosemeters

Aircrew exposure to radiation was measured on several long-haul flights using two small commercial electronic personal dosemeters: one was a photon dosemeter, the NRF20; the other was a neutron dosemeter, the NRY21-both manufactured by Fuji Electric Systems Co. Ltd. for radiation protection at nuclear facilities. Non-neutron doses were measured using the photon dosemeter, and neutron doses were measured using the neutron dosemeter. The measured non-neutron doses at commercial aviation altitudes agree with the EPCARD (European Program Package for the Calculation of Aviation Route Doses) dose calculation within a difference of 8 %. However, the recorded neutron doses were 5-15 times larger than the EPCARD calculation. These over-measurements are dependent on cut-off rigidities.

Fluence-to-dose conversion coefficients for aircrew dosimetry based on the new ICRP Recommendations

The estimation of the fluence-to-effective dose conversion coefficients used especially for aircrew dosimetry is an important issue, since the geometrical conditions of aircrew exposure are considered not to be represented by the standard irradiation geometries such as the anterior-to-posterior (AP) and isotropic (ISO) geometries. We therefore calculated the dose conversion coefficients for neutrons and protons based on the ICRP 2007 Recommendations for three additional irradiation geometries: semi-isotropic irradiation from the upper hemisphere, and geometries closely representing the geometrical situations of aircrew exposure for two different flight conditions. The calculation was performed by the PHITS code coupled with the ICRP/ICRU adult reference computational phantoms. It was found from the calculation that (1) the conversion coefficients for the irradiation geometries closely representing the geometrical situations of aircrew exposure agree better with the corresponding data for the isotropic irradiation than those for the semi-isotropic irradiation; (2) the error associated with the assumption of the isotropic irradiation in the aircrew dosimetry is less than only 1% for conventional flight conditions. These findings indicate the adequacy of the use of dose conversion coefficients for the isotropic irradiation geometry in aircrew dosimetry.

Evaluation of new cosmic radiation monitors designed for aircrew exposure assessment

[1] With the development of next generation aircraft designs capable of ultralong-range flight and extended flight endurance, new experimental dosimetry equipment has been specifically designed to enable aircrew to monitor and respond to airborne alerts of potential doses that exceed recommended limits. The new QinetiQ QDOS/Rayhound monitor and designer-specific Liulin 4SA both provide real-time monitoring and readout with both audible and visual alert functions. The potential advantage to pilots and airlines is a more rational response to an alert by minimizing the altitude descent and time at lower levels in response to a significant event. This not only protects passengers and crew from solar particle events but provides a “greener” option to fuel burn at lower altitudes when events have abated. Thus, it will allow the crew to determine safer optimum flight levels during and after the event. These monitors were flown on numerous high- and low-latitude flights in combination with a “Hawk” tissue equivalent proportional counter acting as the reference instrument as it measured the total ambient dose equivalent H*(10). An FH 41B Eberline monitor and bubble detectors were also used in the comparison.