How stupid. Those things won't do a thing for you if we're attacked by biological weapons. Most of the stuff nowadays is absorbed through the skin and/or goes right through charcoal filters...
While these devices may be about as effective against biological and chemical "weapons of mass destruction" as plastic film and duct tape, :>) this kind of filter mask can be quite useful (health preserving) if you have to deal with concentrated insect spray or paint in close quarters. Of course it is still advisable to cover up with overalls, cap, gloves, etcetera and provide as much area ventilation as possible in addition to wearing a filter mask. This applies at home or at work. What is really stupid is handling toxic materials without proper protection.