Final answer:
Radiation detectors monitor ambient exposure, comparing it to natural and man-made sources, with occupational limits of 20 to 50 mSv/y, requiring frequent checks in high-exposure industries.
Step-by-step explanation:
When to survey ambient radiation exposure level is often determined by the need to ensure that the levels are within safe limits as indicated by authorities like the Environmental Protection Agency. Individuals can assess their average annual radiation dose by utilizing radiation detectors like Geiger counters, scintillators, and dosimeters. This can be compared to natural background radiation, which includes cosmic rays that vary with altitude and latitude, and exposure from man-made sources like medical x-rays or radon in homes.
Occupational exposure limits vary by country but are typically around 20 to 50 mSv/y, with occasional higher allowances for specific body parts like the hands. Public exposure limits are generally set at a fraction of these levels, and significant events such as the Chernobyl can lead to evacuation to prevent dangerous levels of exposure.
Monitoring ambient radiation is particularly important for those working in industries with potentially higher exposure levels, such as airline personnel who, on average, receive about 2 mSv/y due to elevated cosmic radiation exposure at high altitudes. Understanding and measuring one's radiation exposure can help individuals and regulatory bodies manage risk appropriately.