Millions in eleven states told to stay inside

Newsweek - Heat-related warnings from the National Weather Service (NWS) were in effect for parts of 11 states on Friday morning, with officials advising residents in affected areas to keep out of the sun as hot temperatures and high humidity could trigger heat illnesses.

According to the Centers for Disease Control and Prevention (CDC), extreme heat can lead to heat-related illnesses, especially in older adults, young children and those with chronic medical conditions.

Symptoms may include heavy sweating, muscle cramps, dizziness and nausea. The CDC says more than 700 people die each year in the U.S. because of extreme heat.

Additionally, rising temperatures can worsen ground-level ozone pollution, which presents additional health risks. Map of warned states