NBC/CBRN threats Explained

A brief explanation on what NBC/CBRN threats actually are and how a conventional gas mask protects you from them. CBRN is the new term that replaced NBC. CBRN stands for:
Chemical
Biological
Radiological
Nuclear

Most NBC/CBRN filters contain at least two layers, first a P3 particulate filter/HEPA filter which blocks particles such as dust and smoke as well as contaminated fluids entering the mask.
Secondly, a charcoal or carbon filter that adsorbs chemical agents and any liquids that make it past the particulate filter.
For the most part, the charcoal layer blocks the Chemical threats and the particulate filter blocks the biological and nuclear threats.
Industrial filters work the same way, an ABEK-P combination filter being the closest equivalent, some of these are better choices for preppers to stockpile as they also protect from TICs (Toxic industrial chemicals) that can get through standard CBRN filters.
The radiological threat that CBRN gear is meant to protect against seems pointless to me, it either equals to alpha and beta radiation that a standard filter can block as in the N/Nuclear protection or is Gamma radiation that would shoot straight through the filter anyway.