| Remarks |
| 1. |
From readings taken at various locations in Hong Kong during the period 1987-2010, the background ambient gamma radiation levels may vary between 0.06 and 0.30 microsievert per hour. (1 microsievert = 0.000001 sievert = 0.001 millisievert) |
| 2. |
Temporal variations are generally caused by changes in meteorological conditions such as rainfall, wind and barometric pressure. |
| 3. |
Spatial variations are generally caused by differences in the radioactive content of local rock and soil. |
| 4. |
Quality control has not been applied to the above data and the values may be affected by noises. |
