Can the gas mask stop the radioactive?

IIRC from NBC training, the M40A1 can stop the radioactive particles created from the nuclear blast, but even those emit gamma radiation which not many things can stop (i.e. it makes tiny holes in your body). Beta radiation is also a factor, but the sheer power of gamma radiation trumps all. Alpha particles are so big that they are of no concern, if you're properly equipped (i.e. MOPP 4).

Again, this is all from memory of NBC training and physics/engineering courses.

Atleast I won't need to get a haircut anymore...

If they tell us then we'll panic until the nuke hits. If they don't tell us then we'll happily carry on our lives until the nuke hits.

I never did like wearing MOPP Gear...

Either way, we die.