Monitoring of flight personnel

Radiation exposure at different altitudes

At high altitudes people are exposed to considerably more cosmic radiation than at ground level. It is technically not possible to shield aircraft against cosmic radiation. Thus, pilots and flight attendants - especially if they often fly long-haul flights on polar routes - may receive radiation doses which are certainly comparable to the dose values of occupational groups using ionising radiation or handling radioactive sources.

Radiation protection monitoring of flight personnel

The EU Directive 96/29 EURATOM, which was replaced by EU Directive 2013/59 EURATOM, required the radiation protection monitoring of aircrew. In Germany, this requirement was implemented into national law with the amendment of the German Radiation Protection Ordinance in 2001: flight personnel is subject to mandatory monitoring if they are employed according to German labour law and may receive an effective dose of more than 1 millisievert in a calendar year due to cosmic radiation during flights.

The radiation exposure of these employees has to be determined, limited and reduced by considering each individual case. The operators of aircraft are obliged to determine the dose values and to reduce the radiation doses of their employees through appropriate crew scheduling and flight routes.

Radiation exposures of cockpit and cabin crews of German airlines recorded in BfS Radiation Protection Register

Since August 2003, the Radiation Protection Register has been recording the dose values of all individuals occupationally exposed to radiation. These values are measured or calculated on a monthly basis. The Register supervises, among other things, the compliance with permissible annual dose limits and occupational life doses.

As the physical conditions during flights are very well known, the radiation exposure per flight is calculated on the basis of flight data. To this end, the airlines may use computer programs approved by the German Federal Aviation Office (Luftfahrt-Bundesamt, LBA). The programs determine the effective dose resulting from the relevant flight on the basis of physical measurements (for example, neutron flux density) and flight data (origin and destination airport, flight duration and altitude, date).

The airlines report the calculated values to the Federal Aviation Office (LBA) responsible for supervising aircrew and, among other things, the compliance with dose limits. This approach ensures radiation protection monitoring also for flight personnel in a legally secure manner. The Federal Aviation Office (LBA) sends the monthly dose values to the BfS Radiation Protection Register.

Occupational group with comparatively high levels of radiation exposure

Mean annual doses of individuals occupationally exposed to radiation in various occupational groups (n = number of radiation-exposed individuals per occupational group)

In 2019, aircrew with approx. 41,000 employees accounted for about ten per cent of all individuals occupationally monitored for radiation protection purposes entered in the BfS Radiation Protection Register. These ten per cent with a collective dose of about 75 person-sieverts, receive two thirds of the total occupational radiation dose in Germany.

The figure illustrates that - in comparison to other occupational fields involving radiation exposure - aircrew, with an average effective annual dose of 1.82 millisieverts, is the occupational group most highly exposed to radiation. In contrast, the average radiation exposure of medical personnel which amounts to an effective dose of 0.32 millisievert per year is significantly lower.

Comparison of the frequency distribution of the annual doses of occupationally radiation-exposed individuals in various sectors in 2019

A characteristic feature is the difference in the distribution of the doses as illustrated in the figure: for aircrew (blue bars), annual dose values ranging from 1.5 to 2.0 millisieverts occur most frequently, all the others form a roughly symmetrical distribution around this group. In contrast to this, most radiation-exposed individuals in all other occupational fields (medicine, industry, nuclear engineering etc.) only have dose values of up to 0.5 millisievert; with increasing dose values the frequencies decline sharply. For aircrew, however, annual doses of more than eight millisieverts are virtually impossible.

Limited possibilities for minimising radiation exposure

Currently it is technically not possible to shield aircrafts against cosmic radiation. Flying lower altitudes or flight routes involving less radiation is not effective in most cases as it increases costs and environmental pollution; moreover, the scope for action is restricted by flight safety issues which always have priority. Compared to other occupational fields, the possibilities of radiation protection are therefore limited to a few measures in flight planning to reduce flight route doses, and in crew scheduling to ensure a fair distribution of the dose among the crew.