Which method would NOT be used in a mass decontamination scenario?

In a mass decontamination scenario, the objective is to quickly and effectively remove contaminants from a large number of individuals. The correct answer, which is reverse osmosis, is not a suitable method for this type of situation.

Reverse osmosis is a filtration process that removes contaminants from water by forcing it through a semipermeable membrane. While it is effective for purifying water, it is not practical for on-site decontamination of individuals in an urgent scenario due to its complexity, time requirements, and the need for specialized equipment. Mass decontamination often requires rapid and large-scale methods that can handle multiple people at once, which reverse osmosis does not provide.

The other methods mentioned, such as a ladder shower, deckgun, and fogging techniques, are all appropriate for mass decontamination. Ladder showers allow large groups to be decontaminated quickly as water cascades down, while deckguns can spread large volumes of water over a wide area. Fogging techniques can help disperse decontaminants or water droplets effectively, making them suitable for this scenario. Thus, these methods align with the needs of swift and efficient mass decontamination of individuals in emergencies.