Studies on the effectiveness of collective protection in the M1 tank indicate a significant increase in the life expectancy of the vehicle. This increase is due to the increased effectiveness of the crew which can operate in a lower level of MOPP. In addition, hybrid collective protection and overpressure can prevent vapor contamination of the vehicle interior, thereby increasing the amount of time a crew can remain unmasked.
--FM 3-100, NBC Operations, 1985
Collective protection programs are the bastard stepchildren of the CB defense community, which may seem a strange statement to make, since the concept of collective protection is to allow groups of individuals to avoid dressing up in protective suits and masks. Operating inside a shelter that provides clean air in an otherwise deadly environment seems like a preferred option. The down side is that collective protection shelters take time to set up and take down, demand dedicated power sources, rely on huge filters that are expensive and difficult to replace, and are not well integrated into conventional shelter and vehicle design. CB detectors, protective ensembles, and decontamination systems are all unique, stand-alone systems that do not require integration with someone else's programs. 1 When one pushes the requirement of collective protection onto another military defense program, what one must recognize is that one is asking another R&D program manager to make room in their tank/airplane/GP medium tent/shelter system/van/armored personnel carrier/ship for something that is large, power-draining, and hardly ever used in the grand scope of its life cycle. This is a prime reason why there are so few fielded collective protection systems and why, when troops go to war, the stores of large filters are so low (no one's ordering them).
The Army and Marine Corps use collective protection for two distinct functions. The older function is as shelters that exist to provide safe agent-free havens for personnel that may have to operate in contaminated environments for extended period of time and that require freedom from protective suits and masks to function fully. These include communications, command and control (C3) units and hospital units. Various configurations exist for both fixed sites (buildings) and