More than 100 million people across the U.S. are under heat alerts this week alone, according to the National Weather Service (NWS). The NWS recommends staying inside during extreme heat and avoiding outdoor activities when it's too hot out for prolonged periods of time.

But if you must be outside during these conditions — whether it's for work or play — here's what you need to know about how extreme heat could affect your health:

We all know that the heat is the enemy of human being. It is a fact that outdoor workers are more likely to be exposed to extreme heat than indoor employees.

Take a example, Food delivery rider, Construction workers and Sanitation worker whom almost whole day working outside even the extremely heat. We don't know what danger they face to, we enjoy the convenience from their job.

In some countries, such as Japan, they have special clothing for outdoor workers in summer time which helps them to stay cool and comfortable. But this kind of wearable cooling equipment is not popular in other counties yet. However, there are still some ways we can help them:

1-Rest often in shady areas so that your body has a chance to recover.

2-Prepare some handy cooling equipment for stay cool, like the cooling vest and cooling towel.

3-Drink more water.

Watch for signs of heat exhaustion or stroke and seek medical attention immediately if needed

Heat is a silent killer that can cause serious health problems if you aren’t careful. As temperatures rise, so do the risks of heat stroke, dehydration and exhaustion — all of which can be fatal if not treated quickly.