That said, like all things, if you ever intend to purchase an Air Purifying Respirator rated for CBRN threats it will only protect you if you carry it with you, as you know.
These chemicals will likely present a hazard primarily when inhaled and these masks can do a very effective job of managing the consequences of these agents allowing you to remove yourself from the environment. While a wide area, high purity, chemical warfare attack by a state actor on our soil is a low likelyhood event, the possibility of accidental or intentional release of toxic industrial chemicals is much higher. Wiggity, it is a very valid question despite some of the responses.
