Hugh,
I spent 15 years in the nuclear industry working at a nuke plant and was the site Radiochemist most of that time. I have never seen any sort of functional anti-C that will “stop” or even attenuate gamma radiation.
In fact, nothing will “stop” gamma rays. Shielding (lead, concrete, water) can attenuate gamma rays, but it will not “stop” it. Some measurable energy still gets through all shielding. So I am not sure what the author is referring to, but any anti-C that isn’t meant to be disposed of has to be deconned after each use. Of course when you are deconning something, you’re going to want to be wearing anti-Cs, so I guess you would need at least 2 pair? But who wants to try to wear a lead suit around anyway?
Beta and alpha radiation can be attenuated by something as thin as a piece of paper. So most any anti-c you buy will be effective against them. Tyvek suits are used throughout the commercial nuclear industry.
The keys to reducing your radiation exposure are Time-Distance-Sheilding. Reduce the time you spend in areas of high dose rates. Put distance between yourself and sources of radiation. Put shielding between you and any source of radiation.
I think that the safest thing to do if the SHTF event is a nuclear one, would be to shelter in place for at least two weeks following the conclusion of the event. A month would be better. This gives the air time to clear and the short-lived radioactive isotopes time to decay away. If the SHTF event is the meltdown of a nearby nuclear plant and you are down wind and within the plume, then you need to get out of dodge. Anti-Cs are only necessary if you are in a known area of contamination. Anti-Cs will not protect you from receiving gamma radiation dose.
If you are planning for a nuclear event, disposable anti-Cs (and gloves and a respirator) are the only way to go. Of course, you need to learn the proper technique in donning and doffing anti-Cs or they will be useless to you, as you will likely just contaminate yourself and your shelter.
Regards, – J.P.