MANILA, Philippines – It’s that time of the year when most, if not all, people complain about the scorching heat. Variations of “Ang init!” (It’s so hot!) are all too common.

During the dry season, temperatures soar, as expected. But temperatures aren’t the only thing contributing to the feeling of worsening heat – there’s also humidity, which refers to the atmosphere’s moisture content.

When the actual air temperature and the relative humidity at a given time are combined, the result is what’s called the heat index.

Simply put, the heat index is what people “perceive or feel as the temperature affecting their body,” according to the state weather bureau.

For instance, in Dagupan City in Pangasinan, the actual air temperature reached 36.7°C on April 9, 2019. But combined with 62% relative humidity, the heat index surged to an intense 51.7°C. People in Dagupan “felt like” it was 51.7°C there.

As the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) explained, “High air temperatures and high relative humidity will give high apparent temperatures or indices.”

It’s worse with “full exposure to sunshine,” as this “can increase the heat index by 8°C,” warned PAGASA.

What are the effects?

Here are the potential effects when the heat index reaches the following temperatures, according to PAGASA:

• 27°C to 32°C – Caution
• Fatigue is possible with prolonged exposure and activity.
• Continuing activity could result in heat cramps.
• 32°C to 41°C – Extreme Caution
• Heat cramps and heat exhaustion are possible.
• Continuing activity could result in heat stroke.
• 41°C to 54°C – Danger
• Heat cramps and heat exhaustion are likely.
• Heat stroke is probable with continued activity.
• Over 54°C – Extreme Danger
• Heat stroke is imminent.

How can people protect themselves?

PAGASA gave the following tips:

• Stay indoors as much as possible. If air-conditioning is not available, stay on the lowest floor, out of the sunshine.
• Wear lightweight and light-colored clothing.
• Drink plenty of water regularly.
• Water is the safest liquid to drink during heat emergencies. Avoid drinking liquor because it dehydrates the body.
• Eat small meals, but eat more often. Avoid eating food high in protein which can increase metabolic heat.

– Rappler.com