The native terrestrial radioactive background radiation is recorded on a regular basis on a web server. This automatically takes over the data from the last 30 days. A graph is then edited as below ...
Gamma dose rate for the last 30 days
Understanding the "Last 30 Days" graph
- On the ordinate: the scale gives the dose values for the last 30 days (µSv / hr)
- On the x-axis: the scale indicates the space-time by 30 minutes of the last 30 days
- "Average" indicates the average of the doses received during the last 30 days
- "Min" is the minimum dose over the last 30 days
- "Max" is the maximum dose over the last 30 days
Dose rates
The radioactive dose rate is the radioactive dose per unit of time. It is measured in Gy / s (grays per second) in the international system of units, but the commonly used units are Gy / h and formerly rad / h (rad per hour). The equivalent dose is measured in sieverts and in submultiples for the usual doses.
Dose rate measurement:
The equivalent dose rate is measured in sieverts per hour (Sv / h) or per second (Sv / s).
--> mSv / h (milliSievert) -> Divided by 1000: µSv / h (microSievert) -> Divided by 1000: nSv / h (nanoSievert)
Doses
A dose delivered slowly (low dose rate) has less impact than the same dose delivered more quickly (high dose rate).
A dose rate of 2 µSv / h is considered tolerable: it is the dose rate received by populations living in regions with high natural radioactivity. It corresponds to an annual dose of 17.5 mSv per individual.
The integral of the dose rate received by an operator (the total effective dose) is measured by a dosimeter. This overall measurement does not take into account the dose rate, which can lead to very different health effects. (Wikipedia)
Measures
