My Father Is In A Country Thats Experiencing A Heat

My father is in a country thats experiencing a heat wave. he is 70 yrs old. He said his symptoms were dizzinness, trouble breathing, heavy chest and some sharp pains in the chest. Am not there with them but i asked him to go into a hospital, he said as soon as he gets some energy. How urgent is it for him to seek medical attention? I also told him that he needs to get an EKG test done.
Thank you