Seoul Metro has once issued a "map" of subway trains to help passengers avoid being too cold or too hot, as it turns up the air conditioning in the summer heat.

There has been a 60 percent increase in complaints regarding uncomfortable heating and cooling conditions on trains compared to the same month last year, Seoul Metro said, issuing guidance on subway usage on Thursday.

From January to May of this year, complaints about "being hot" increased by approximately 60 percent. Similarly, complaints about "being cold" increased by about 65 percent.

Seoul Metro stated that different individuals perceive temperatures differently, and there are often cases where complaints about "being hot" and "being cold" arise simultaneously within the same train. In response, the transportation authority has advised passengers to move to the ends of the train if they feel hot, as the temperature tends to be lower there, while passengers who feel cold should move towards the center of the train, where cars have reduced air conditioning, or the designated partially air-conditioned train cars.

Seoul Metro explained that the partially air-conditioned cabins on lines 1, 3, and 4 are located in the 4th and 7th cars, on lines 5 to 7 they are in the 4th and 5th cars, and on line 8 they are in the 3rd and 4th cars.

However, it should be noted that line 2 does not have partially air-conditioned cabins due to its high level of congestion. Additionally, Seoul Metro encouraged passengers to utilize the "Ttajja Subway" or "T Map" mobile applications to check the predicted congestion levels of trains.