What is a safe radiation exposure level?
In 2007, an international group of scientists studied 2000 peer-reviewed and published research papers.
They created the Bio-iniative report, (updated in 2022 updated Report). They recommended an acceptable level of radiation based on having no observable effect on humans, with a factor of 10 added for safety, this became known as the Bioiniative safety level.
The level is not more than 0.6 V/m = 1 microwatt per centimetre squared outdoors, and 0.2 V/m = ~0.1 microwatt per centimetre squared indoors, based on the interaction between low-level microwaves and the cellular processes.
This has since been lowered by a factor of 10,
to 0.01 μW/cm2.
Bioinitiative proposed safety level of radiation:
0.01 microwatt per centimetre squared.
A microwatt is equal to one millionth of a watt (10-6). Its unit is µW
(Conversion: 1 µW = 0.001 mW = 0.000001 W)
By comparison the natural level of radiation:is less than 0.000001 microwatt per metre squared
"A realistic approach to those who want to limit their exposure to elevated (according to the proposed limits) wireless radiation values is to avoid places with values greater than 100 microwatts / m2 during the day and places with values greater than 10 microwatts / m2 in sleeping areas)".— Michael Kagelidis Certified Building Biology practitioner
The New Zealand safety limit (NZ2772.1.1999) for the specific absorption of radiation from transmitters close to the body (ie cell phones) is 2W/KG over any 10 grams of body tissue. This standard is really based on protecting the body from heating effects, ignoring biological effects found in exposures at or under this level. It does not take account of developments in information and communication technologies or vulnerable groups, such as pregnant women, newborn babies and children or hypersensitive people. Check the New Zealand government information site.
There are a great deal of other standards and recommendations, some include specific recommendations for schools and hospitals. This building biologist site has a very good discussion of the other standards Other standards recommendations
There is also a 2023 update on exposure standard recommendations of some of the bigger players, where you can see that the ICNIRP recommendations we follow are hugely different than the Council of Europe's recommendations.