With the price of gas soaring, swimming pools across France are turning down the heat. One suburban Paris outdoor pool has turned off the heating altogether and made wetsuits compulsory for swimmers. Before Russia’s war on Ukraine sent gas prices soaring, the Olympic-size open-air pool in Nogent-sur-Marne was warmed to a comfortable 26°C. Now, the temperature hovers around a chilly 19°C. Many bathers had already taken to using wetsuits. But from October, the pool made them compulsory, to prevent medical emergencies among people not used to swimming in cold water. Why are swimming pools in Fran…