In aviation, employees are exposed to cosmic radiation. Cosmic radiation is particle radiation emitted by the sun or from space. If it is possible that the effective dose of cosmic radiation to the aircrew may exceed 1 millisievert (mSv) per year, the air operator must investigate the amount of exposure to cosmic radiation to aircrew and apply for a safety licence. 

Particles from the sun rarely have enough energy to reach the lower part of the Earth's atmosphere. Instead, galactic radiation from outside the solar system is more energetic and can enter the lower atmosphere. 

The Earth's magnetic field and atmosphere protect us from cosmic radiation on the Earth's surface. The higher you rise from the ground, the weaker this protection will be. The dose rate of cosmic radiation is also influenced by latitude, longitude and solar activity. 

Flying exposes you to cosmic radiation 

Suomessa ihmisille aiheutuu maan pinnalla avaruussäteilystä keskimäärin 0,38 mSv:n efektiivinen In Finland, people receive an average effective dose of 0.38 mSv per year from cosmic radiation on the ground. Passenger planes fly at an altitude of approximately ten kilometres, where the dose rate is a few tens of times higher than on the ground. In most cases, the radiation exposure remains relatively low, as air passengers are exposed to cosmic radiation occasionally and only for short periods at a time. However, the exposure times of aircrew can be up to hundreds of hours per year. Therefore, their exposure to radiation must be monitored. 

Air operators must submit a notification of engagement in aviation and a report on radiation exposure 

Air operators must submit a notification of engagement in aviation to the Radiation and Nuclear Safety Authority (STUK) before carrying out the operations.

The notification can be submitted to [email protected].

An air operator holding a licence issued for this purpose by the Finnish Transport Safety Agency (currently the Finnish Transport and Communications Agency Traficom) is obligated to investigate the radiation exposure arising from its practice, if the principal flight altitude is more than 8,000 metres. 

Safety licence in aviation operations  

In addition to the licence issued by the Finnish Transport and Communications Agency Traficom, aviation operations require a safety licence granted by STUK if the radiation dose caused to aircrew by the operations is higher than the reference value, i.e. 1 mSv per year.  

Aircrew as radiation workers  

Under the current radiation legislation, the flight personnel are classified as radiation workers. However, not all provisions for radiation workers are applicable to aircrews.  

Unlike other radiation workers, aircrews do not need to be classified as category A or B radiation workers, nor do they need the health monitoring of a radiation worker. The radiation exposure of aircrews is determined using calculation programs, which is not possible in other types of radiation work. 

Monitoring of radiation exposure  

If the abovementioned report shows that the aviation operation requires a safety licence, i.e. the effective dose to the workers may exceed 1 mSv per year, the operator must monitor their radiation exposure. In addition, the operator must plan the work shifts of the aircrew in such a way as to limit the exposure of the most exposed workers. Shifts and flight routes must be planned so that the effective dose of the worker does not exceed 6 mSv per year. 

The aviation work of a pregnant woman must be so arranged that the equivalent dose to the fetus is less than 1 mSv and as low as reasonably achievable. 

Cosmic radiation doses are generally not measured, but they are determined using a computationally appropriate and proven calculation program. The results of radiation exposure monitoring are reported annually to STUK's Dose Register. 
When flying at an altitude of more than 15 kilometres, it is necessary to prepare for a sudden solar flare. This preparedness is ensured by using on-board measuring equipment that can be used to determine the workers' dose. 

More detailed instructions on how to ensure the monitoring of radiation exposure in aviation operations are provided in the Radiation and Nuclear Safety Authority regulation on the investigation, assessment and monitoring of occupational exposure and the Regulation on practices that cause exposure to natural radiation. 

Employees have the right to be informed of their own exposure 

The operator must ensure that employees receive adequate information on cosmic radiation and its health hazards. Employees must also be informed of their own radiation exposure and of the exposure typically caused by similar work. 

Women must be provided with information about radiation protection during pregnancy. In addition, they should be advised to report their pregnancy to the employer immediately after the pregnancy is confirmed, so that the exposure of the fetus can also be properly monitored.