Final answer:
Negative pressure respirators are devices that allow air to enter the facepiece when the wearer inhales, creating a negative pressure. These differ from positive pressure respirators, which supply air continuously to maintain a positive pressure, preventing ingress of contaminants. Such respiratory technology has been improved by aerospace innovations, making them safer and more effective.
Step-by-step explanation:
Negative pressure respirators are atmosphere-supplying respirators that admit breathing air to the facepiece only when a negative pressure is created inside the facepiece by inhalation. These types of respirators are distinct from positive pressure respirators, which supply air continuously or on demand to create a positive pressure within the mask, preventing contaminants from entering. The concept of negative pressure is crucial as it implies pressure lower than the atmospheric pressure, which is key to the function of these respirators. They rely on the user's inhalation effort to draw air through a filter or from a clean air source.
For example, scuba divers use a form of negative pressure respirator as they must inhale to initiate the flow of air from their tanks. On the other hand, positive pressure suits or respirators, like those used in BSL-4 laboratories, provide a continuous flow of air to prevent environmental contaminants from entering, even if a leak occurs. These contrasts in design are also evident in medical applications, where positive pressure ventilators may assist patients by pushing air into the lungs, unlike negative pressure respirators that require the patient's inhalation effort.
The development of these respirators has benefited from technologies such as those developed by NASA, including lightweight materials and communication systems, enhancing the safety and effectiveness of respiratory protective equipment for various applications.