What is the National Council on Radiation Protection's (NCRP) recommended maximum annual equivalent dose to the general public for frequent exposure?

• A. 10 millisievert (mSv).
• B. 50 millisievert (mSv).
• C. 1 millisievert (mSv).
• D. 5 millisievert (mSv).

Answer: (C)

Public exposure limits aim to minimize long-term cancer risk for people who are not workers. The NCRP sets a conservative cap for the general public: an annual effective dose of 1 millisievert for frequent exposures. This single-number limit accounts for the fact that many small, ongoing sources of radiation can add up over a year, so keeping the total around 1 mSv helps limit lifetime risk.

Because this is an effective dose limit for the public, it is lower than occupational limits (which are higher to account for workers’ higher exposure) and lower than the other numbers listed. A value like 10 mSv or 5 mSv would imply substantially higher annual risk, and 50 mSv is in line with occupational standards rather than public exposure.