Sure, when you use hundreds of watts over several minutes. The decay over distance should be roughly exponential: every x millimeters, you're left with only ha

Sure, when you use hundreds of watts over several minutes. The decay over distance should be roughly exponential: every x millimeters, you're left with only half of the radiation. Given the radiation caused by a cellphone in your pocket, how many microns of water do you need to attenuate the intensity to a non-mutagenic level?