A merchant drinks water in Yangsan, South Gyeongsang Province, on Sunday, when the city recorded a record high temperature of 42.5 C. (Yonhap) Temperatures have neared or exceeded 40 degrees Celsius across South Korea, prompting local governments to send drones over farmland and refrigerated trucks through city streets to protect residents from the prolonged heat wave.The measures mark a shift from waiting for vulnerable residents to visit cooling shelters to finding them before they fall ill.Asan in South Chungcheong Province has deployed drones equipped with cameras that use artificial intelligence to detect people working in fields, as well as loudspeakers that broadcast heat safety warnings. Vast stretches of farmland and areas inaccessible to vehicles make conventional ground patrols difficult.When a drone spots someone working outdoors, it broadcasts messages urging the person to go indoors, drink water and rest. It can also relay the worker’s location to municipal response teams, which can direct the person to a nearby cooling shelter if necessary.Health Minister Jeong Eun-kyeong visited the area Monday and recorded a safety message that is now played during the patrols. A drone patrols a heat-vulnerable farming area in Sejong as disaster response workers conduct an on-site inspection. (Sejong City) Buk-gu, Gwangju, and Sejong have also deployed drones over farmland and other areas considered vulnerable to extreme heat.In Hwasun, South Jeolla Province, six drones recently patrolled during the hottest hours of the day. They spotted 304 farmers and older residents outdoors and persuaded 116 of them to stop working and return home.“Older residents often do not fully recognize the dangers of extreme heat,” a Hwasun County official was quoted as saying. “Even when we advise them to go home, many insist on continuing to work.”Yangsan in South Gyeongsang Province, where a temperature of 42.5 C was recorded Sunday, has introduced two refrigerated trucks that distribute free chilled bottled water between noon and 3 p.m.The trucks visit about 30 heavily used public locations, including traditional markets, parks, outdoor sports facilities and bus stops, handing out about 1,000 bottles a day. Since Monday, the city has also increased the number of water-spraying trucks from two to 24 to cool road surfaces and installed additional cooling fog systems.Elsewhere, Hwaseong, Yongin and Gwangmyeong in Gyeonggi Province have begun lending parasols free of charge at community centers, libraries and other public facilities.The expanded measures come as the prolonged heat wave takes a growing toll.As of Tuesday, 19 suspected heat-related deaths had been reported since the government began monitoring cases on May 15. The number of patients treated for heat-related illnesses reached 2,025 after 186 cases, including two deaths, were recorded Monday.