November 2016, this is a Leonidas Aviation 430 1 day clock with a Leonidas 45C movement. It needs a cleaning service after being installed for 64 years in an Saab Safir 91B. A new glas and new luminous compound will be done as well.
It is save to work on this clock, no radioactive luminus compound used.
Normal Values of Exposure to Radiation, Limit Values
For individuals with professional exposure to radioactive sources in the EU,
there are two legal upper limits:
Dose rate limit is 6 mSv p.a. = 3 μSv/h (assuming 2,000 working hours per year), Cat B
Dose rate limit is 20 mSv p.a. = 10 μSv/h (assuming 2,000 working hours per year), Cat A
(An exclusion zone exists starting at 3 mSv/h)
The natural environment in Heidelberg, Germany
has a radiation level of about 0.1 - 0.2 μSv/h