Radioactive definition examples

The activity of natural uranium is 710 nCi/g. So soil or rock containing natural uranium at a concentration of 0.3 per cent or more is "radioactive" by this definition.

The activity of carbon 14 in air is 0.03 Bq/g of air - about 2 disintegrations per minute per liter - bout 2000 times below the definition of radioactive.