Many hospitals are equipped with negative and positive pressure rooms just for the purposes described. Negative pressure rooms are used to help keep airborne pathogens (eg. aerosolized COVID-19 and active TB) from escaping into surrounding areas, thereby preventing the spread of airborne pathogens to outside the room. Positive pressure rooms are used for immunocompromised persons (eg. Neutropenic) whereby controlled quality air is sent into the room to prevent random (and potentially polluted) air from entering the room.