Table 1 Illustrative radiation exposures from natural background, medical, routine nuclear operations and Chernobyl with hypothetical lifetime risks.
Exposure scenario | Exposure | Mortality risk+ | Notes |
|---|---|---|---|
Examples of radiation exposures not due to Chernobyl | |||
General population (background exposures) | |||
UK average (natural + medical) | 200 mSv | 1 % | Lifetime (~75 yr) exposure to 2.7 mSv yr-1 UK average annual dose. |
Exposure at UK limit for radon exposures in the home [49] | 750 mSv | 3.7 % | Lifetime (~75 yr) exposure to UK limit 200 Bq m-3 radon gas ≈ 10 mSv yr-1 dose. Above this limit, action must be taken to reduce radon in houses in the UK. Dose depends on time spent at home and doses at this high rate are rare. |
Working population (above background)* | |||
UK average for classified radiation workers [50] | 18 mSv | 0.07% | Average current dose (above background) of classified workers in the nuclear industry of 0.6 mSv yr-1 accumulated over a 30 year working period. |
Long haul air crew [51] | 135 mSv | 0.54% | Typical exposures in the range 3–6 mSv yr-1: assume 4.5 mSv yr-1 over 30 yrs |
Exposures after Chernobyl (above background)* | |||
General population | |||
Residents of "strict control zones" (areas > 555 kBq m-2 137Cs). | 50 mSv | 0.25% | Accumulated dose for approximately 10 year period after the accident [37, 52] |
Annual dose limit to populations of the Chernobyl affected areas, 1990's | 75 mSv | 0.37% | If external + internal dose exceeded this limit, measures had to be taken to reduce dose. Accumulated dose at 1 mSv yr-1 over 75 yr lifetime [53] |
Consumer of sheep meat from the most contaminated areas in the UK | 4.1 mSv | 0.02% | Consumption (at a high rate) of lamb from farms most affected by Chernobyl for 75 year period (assumed mean 137Cs = 500 Bq kg-1 in 1986, declining with effective half life 25 yr). Over-estimate of likely real exposures. |
Working population | |||
Unofficial residents of the 30-km exclusion zone. In late 1990's range of doses in a number of villages [2], Ukrainian sector 30 km zone was 1–6 mSv y-1 | 255 mSv | 1.0% | Illustrative of higher exposures: person of working age (25) who received 100 mSv during period to 1995, then returned to Zone in 1996 and received 6 mSv yr-1 in 1996 declining (with effective half life 25 years) to age 75 in 2036. N.B. some (uninhabited) areas of the Zone would give much higher doses. |
Chernobyl emergency workers [37]: Average High dose group | 100 mSv 250 mSv | 0.4% 1.0% | Accumulated risk from exposures during 1986–87. Does not include very high exposures to those who suffered from ARS. Working population. |