Final answer:
A simple water shower system is the most effective and efficient method for mass decontamination, although other methods have their specific applications in handling different types of contaminants.
Step-by-step explanation:
Mass decontamination (decon) can most readily and effectively be accomplished with a simple water shower system. This method is capable of rinsing away a wide variety of contaminants from a large number of people in a rapid and efficient manner. It is important to note that other methods such as dry methods, neutralization, and absorption and adsorption also have their merits in specific situations. For instance, neutralization is used to reduce the environmental impact of effluents by adding strong acids to neutralize harmful substances before they are released into the environment. Additionally, materials for absorption and adsorption can be utilized to clean up chemical spills by soaking up or binding the contaminants. Nonetheless, for immediate and large-scale decontamination scenarios, such as in chemical spills or hazardous material incidents, employing a water shower system proves to be a practical default approach.