Activities that expose people to cosmic radiation

Cosmic radiation is particle radiation from the sun or other parts of space. If there is a possibility that the effective dose of aircrews due to cosmic radiation could exceed 1 mSv per year, the responsible party engaged in aviation operations must investigate the extent of cosmic radiation exposure of aircrews.

Cosmic radiation is particle radiation from the sun or other parts of space. Particles originating in the sun rarely have enough energy to enter the Earth’s lower atmosphere. Galactic radiation from outside the solar system, however, has greater energy and may reach the lower atmosphere. The earth’s magnetic field and atmosphere protect us from cosmic radiation on the earth’s surface. The higher we travel above the surface, the weaker the protection becomes. The dose rate of cosmic radiation is also affected by the latitude and longitude along with solar activity.

Flying exposes people to cosmic radiation

In Finland, people on the earth’s surface are exposed to an average effective dose of 0.38 millisievert (mSv) per year due to cosmic radiation. Passenger planes fly at an altitude of approximately 10 km, where the dose rate is a few dozen times greater than on the earth’s surface. Usually, the radiation exposure remains fairly minor because flight passengers are exposed to radiation only occasionally and for short periods of time. The exposure times of aircrews, on the other hand, may amount to hundreds of hours annually. This makes it important to monitor their radiation exposure.

Responsible parties engaged in aviation operations submit reports on radiation exposure

If there is a possibility that the effective dose of aircrews due to cosmic radiation could exceed 1 mSv per year, the responsible party engaged in aviation operations must investigate the extent of cosmic radiation exposure of aircrews under Section 45 of the Radiation Act. More detailed instructions for the investigation are available in Guide ST 12.4. The Radiation and Nuclear Safety Authority uses the investigation report as a basis for determining whether the operations constitute radiation practices.

Monitoring of radiation exposure

If the aforementioned report indicates that the operations constitute radiation practices, meaning that the effective dose of the personnel could exceed 1 mSv per year, their radiation exposure must be monitored individually. Work shifts and flight paths must also be planned in a way that ensures that the effective dose of an employee does not exceed 6 mSv per year.

The aviation work of pregnant women must be organised in a way that ensures that the equivalent dose of the foetus is below 1 mSv and as low as reasonably achievable.

The dose caused by cosmic radiation is not usually measured but rather calculated using appropriate calculation software that has proven to be reliable. The results of the monitoring of radiation exposure are reported annually to the Radiation and Nuclear Safety Authority’s dose register.

More detailed instructions on ensuring the radiation safety of aviation operations are available in Guide ST 12.4.

Employees have the right to information about their exposure

The responsible party must ensure that employees receive enough information about cosmic radiation and its impact on health. Employees must also be informed of their radiation exposure and the typical exposure in similar work.

Women must be given information about radiation protection during pregnancy and urged to inform the employer of their pregnancy immediately after the pregnancy is discovered so that the exposure of the foetus can be appropriately monitored.