What is the natural radiation level in Hong Kong ? Is it safe ? How does it compare with other places in the world ?

The unit for measuring radiation dose is milli-Sievert (abbreviated "mSv"). The annual dose received by people in the world arising from natural background radiation ranges from 1 mSv to 10 mSv. On average, the annual dose received by a member of the public in Hong Kong is about 2 mSv, which is comparable to the worlds average.