negative pressure

Negative pressure occurs when the pressure inside a space or object is lower than the surrounding environment. This creates a difference in pressure that causes air or fluids to flow into that space. For example, in hospitals, negative pressure rooms are designed to prevent contaminated air from escaping, by keeping the air inside at a lower pressure than adjacent areas. This principle helps contain airborne pathogens. In everyday life, negative pressure can be felt when you suck on a straw—the air pressure inside the straw is lower than outside, drawing liquid upward.