How does air conditioning work, and how does it affect your body?

EXPLAINERWhile AC keeps us cool, it can also cause dry skin and irritation. Here are some tips to keep comfortable this summer.Summer is here and temperatures are rising across the Northern Hemisphere, where nearly 90 percent of the world’s people live. The heat is pushing people to rely on air conditioners to stay comfortable.While air conditioners provide relief from extreme heat, they also remove moisture from the air, which can cause skin dryness and irritation.In this visual explainer, Al Jazeera breaks down how air conditioners work, what they can do to your health and practical tips to protect yourself while you stay cool.How does an air conditioner work?Air conditioners work by removing heat and moisture from indoor air and releasing it outside.The process starts when the indoor unit pulls in warm air and sends it over cold evaporator coils. Inside the coils, liquid refrigerant absorbs the heat, evaporates into a gas and cools the air. A fan then blows the cooled air back into the room.The now-warm refrigerant gas travels to an outdoor unit, which releases the heat through a condenser coil that turns it back into a liquid.The liquid refrigerant returns indoors to repeat the cycle.(Al Jazeera)When was AC invented?The invention of modern air conditioning is generally credited to the American engineer Willis Carrier, who in 1902 designed a humidity-control system for a New York printing plant using chilled coils.Window-mounted units followed in 1931, and after World War II, mass production brought AC into homes and offices.An air conditioner is mounted in the window of an office, circa 1955 [File: Lambert/Getty Images]By the 1990s, growing environmental concerns led to the phaseout of ozone-depleting chlorofluorocarbons, or CFCs, in favour of hydrofluorocarbons (HFCs).