In managing spills of hazardous substances like mercury, pesticides, and battery acid, containing all residues in a sealed container is a critical strategy. This approach prevents the spread of hazardous materials, reduces the risk of exposure to building occupants, and facilitates safe and appropriate disposal. It aligns with the WELL Building Standard's emphasis on health and safety, ensuring that the building's waste management plan includes procedures for promptly and effectively dealing with hazardous spills to minimize health risks.