Final answer:
The average annual radiographic exposure for individuals in the US is around 620 mrem, with natural sources like radon and cosmic rays contributing significantly, and artificial sources also playing a role. Radiation protection strategies are used to minimize the associated health risks.
Step-by-step explanation:
The average annual radiographic exposure to individuals living in the United States is about 620 millirem (mrem). This exposure comes from a combination of natural and artificial sources. Naturally occurring radiation contributes about 150 to 600 mrem per year to this average, with radon being the most significant natural source, accounting for over half of the exposure. Other natural sources include cosmic rays, which vary based on altitude and latitude with higher exposure at higher altitudes; for example, airline industry personnel receive about 2 mSv per year, and a 12-hour flight can result in an exposure of 0.02 to 0.03 mSv.
By comparison, the worldwide average radiation exposure from natural sources is approximately 3 mSv, or 300 mrem. Radiation protection measures like shielding, maintaining distance, and limiting time of exposure are employed to help reduce these radiation risks.
Overall, even though we are exposed to radiation from various sources, the risks associated with these levels of exposure are relatively small.