Yes
Yes it would.
EDIT: foil would actually stop all radio waves from reaching your head if you wrapped it entirely around your head. However, leaving a space for your neck would mean that there may be some penetration into your brain caused by diffraction, which would (of course) depend on the size of your neck and the wavelength of the radio waves in question.
Safest to wear a total foil suit or live in a Faraday cage if you are truly worried about such things.
( ,
Sat 2 May 2009, 23:06,
archived)
EDIT: foil would actually stop all radio waves from reaching your head if you wrapped it entirely around your head. However, leaving a space for your neck would mean that there may be some penetration into your brain caused by diffraction, which would (of course) depend on the size of your neck and the wavelength of the radio waves in question.
Safest to wear a total foil suit or live in a Faraday cage if you are truly worried about such things.