Areas for quarantine, hazardous substance studies, and nonhuman primate rooms should be kept at ______________ pressure.

The correct choice is negative pressure for areas designated for quarantine, hazardous substance studies, and nonhuman primate rooms. Maintaining negative pressure in these types of areas is crucial for containing potential pathogens or hazardous substances. This ensures that any airborne contaminants are drawn into the room and not allowed to escape into adjacent areas, thereby protecting personnel and other animals from potential exposure.

In quarantine settings, negative pressure helps prevent the spread of infectious agents since animals being housed in these environments might be sick or carriers of disease. Similarly, during hazardous substance studies, there may be chemicals or toxins that need to be contained strictly within the study area. For nonhuman primates, controlling the environment and ensuring safety, both for the animals and the staff, is critical, as these animals may also carry zoonotic diseases.

Positive pressure is typically used in clean rooms where the goal is to prevent contaminants from entering, which is not suitable for quarantine or hazardous study areas. Neutral pressure does not actively contain or prevent the emission of contaminants, and atmospheric pressure does not provide any differential pressure to manage airborne pathogens effectively. Thus, negative pressure is the best practice for these sensitive environments.