MANILA, April 11 -- The city government of Manila will formulate a heat index action plan matrix that will serve as a guide for its response efforts to scorching temperatures as the El Nino phenomenon persists.

Mayor Honey Lacuna said Thursday she has directed the city's health office, social welfare services, and disaster risk reduction and management office to draft the plan.

"Manila's adapted heat index system should indicate when residents shall be required to stay indoors when outdoor activities at school and work shall be suspended, when face-to-face classes and onsite work shall be suspended, and when businesses that use a lot of water should reduce water use or limit their operations at night or temporarily stop operations for t...