Dr. Matthew Fink says in the New York Times that changes in air pressure can cause physical discomfort. Headaches and joint pain are common in low pressure systems, and uncomfortable ear popping can occur as the body tries to equalize the pressure inside its cavities with the changing atmospheric pressure.
ACS Distance Education explains that air pressure is the force exerted by the weight of air molecules. Atmospheric pressure is determined by the amount of air directly above a person or object. At sea level, the atmospheric pressure is 14.7 pounds per square inch, or PSI. At higher altitudes, the PSI decreases due to lower air pressure and density. Skin adjusts easily to changes in pressure, but the cavities within the body, such as the lungs, ears and sinuses, do not adjust automatically. This is why many people experience a popping in their ears while taking off in an airplane or driving through mountains.
Dr. Fink explains other effects that may be felt by the body under these circumstances or during a low pressure weather system. The difference in pressure between the body's cavities and the atmosphere can result in headaches or distension in the sinuses, which are filled with air. People who suffer from arthritis or bursitis may experience joint pain as their muscles and joints swell in response to the decreased pressure on their bodies.