The Seoul Metropolitan Government has raised its heat wave crisis alert to the highest level of "serious" and began operating the heat wave disaster and safety countermeasures headquarters, with the heat wave warning issued for the capital in place for the seventh day.

At an emergency meeting with officials on Tuesday, Seoul Mayor Oh Se-hoon ordered the operation of the headquarters composed of ten divisions, for the first time. 

Under the latest measures, cooling centers in the city will run extended hours through 9 p.m., while more than 220 sprinkler trucks will be deployed five to six times a day.

The city government plans to operate the so-called "cooling road" system of spraying underground water on the roads to cool down the surface temperature.

It will also restrict outdoor work on construction sites between 2 and 5 p.m., and recommend flexible hours for the workers.