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Barometric pressure
Barometric pressure, also called atmospheric pressure or air pressure
Barometric pressure, also called atmospheric pressure or air pressure, is the force or weight of the air surrounding us. Barometric pressure is measured by an instrument called the barometer. One of the commonest types of barometers is a mercury barometer in which the height of a column of mercury that exactly balances the weight of the column of atmosphere over the barometer represents the barometric pressure at that point. At standard sea level, the barometric pressure equals 760 mm (29.92 inch) of mercury. A rise in barometric pressure is generally considered an improvement in the weather, while a fall in barometric pressure may mean worsening weather.
A fall in barometric pressure can affect health in various ways.
- Mountain sickness or altitude sickness: It refers to a group of general symptoms occurring on climbing or walking to a higher altitude or elevation too quickly. At heights above 1,500-3,000 m (5,000-10,000 feet), the pressure is low enough to produce altitude sickness. This happens especially when the person ascends too rapidly not allowing their bodies to adapt or acclimatize to the fall in pressure and oxygen levels with increasing height. The symptoms may include:
If left untreated, the symptoms may progress to severe breathlessness, cough, vomiting, confusion, and unconsciousness. These symptoms occur because the fall in barometric pressure allows the tissues in the lungs and brain to swell (visualize the change in the size of a sponge when you squeeze and release it) in an attempt to get more oxygen. The dilated blood vessels in the brain may cause headaches and swelling of the brain. The swelling puts pressure on the brain, squeezing it against the skull.
Altitude sickness may rarely advance to a more severe form of the illness called high altitude cerebral edema (HACE). HACE occurs when brain swelling becomes severe, manifesting as severe headache, confusion, lethargy, lack of coordination, irritability, vomiting, seizures, coma, and eventually death if untreated. Severe altitude sickness may cause the capillaries (tiny blood vessels) in the lungs to become swollen and leaky. This leads to an accumulation of fluid in the air sacs of the lungs. This condition is known as high altitude pulmonary edema (HAPE). HAPE severely decreases the exchange of oxygen in the lungs, which may cause breathing difficulties and even death.
- Worsening of arthritis: It refers to the inflammation of joints. This may be due to the changes in the joint fluid as the pressure changes. Arthritis manifests as painful, swollen joints that may be associated with joint stiffness. Elderly people often describe the pain associated with a fall in barometric pressure as a storm coming in their knees (storms are associated with a sudden fall in barometric pressure). Some people may be more sensitive to weather changes experiencing more stiffness, pain, and swelling with a barometric pressure decline. Scientists suggest that a fall in air pressure allows the tissues (including muscles and tendons) to swell or expand. This exerts pressure on the joints resulting in increased pain and stiffness. A fall in air pressure may exert a greater effect if it is accompanied by a fall in temperature as well. A lower temperature makes the joint fluids thicker eventually worsening the symptoms.
- Headaches: Some people report worsening of headaches including those caused by sinusitis (sinus inflammation) and migraines when the barometric pressure falls. The skull has several air pockets called sinuses that keep the skull light. When air pressure drops, there is a difference in the pressure of the outside air and the air in your sinuses. This can cause a headache with a small change in pressure. This is the same reason why your ears “pop” when the airplane ascends causing a difference in the air pressure on either side of the eardrums. When the barometric pressure falls beyond a certain limit, there may be associated swelling of blood vessels and tissues in and around the brain causing worsening of headache. The pain is generally felt in one or both temples along with other symptoms such as nausea, vomiting, intolerance to light, and numbness in the face and neck.