How much ionising radiation is needed to cause skin burns, hair loss or death?
These effects of radiation exposure are known as ‘early effects’. They only occur if an individual has received a relatively large dose, in a short period of time, which exceeds a certain threshold level. If a dose is received below this threshold then no early effects are observed. The thresholds for these early effects start at around 1 Sv. A dose of 5 Sv is generally considered lethal. Therefore, to put this into context, you would have to receive approximately 400 years worth of natural UK background radiation in a matter of hours to reach these thresholds.
