With record-high temperatures becoming the norm, humans are more regularly hitting the threshold of our ability to cope with heat.
Why it matters: Nearly 190 million were under some form of heat advisory or warning as of Monday afternoon, Axios' Alex Fitzpatrick reports.
The extreme weather broke temperature records across the West and Alaska before shifting east, bringing an especially dangerous combination of heat and humidity.
Zoom in: Maricopa County experienced 602 heat-related deaths last year, according to its Department of Public Health.
Reality check: Some groups face a disproportionate burden of extreme weather due to factors such as income, education, health care access and housing, according to the EPA.
Heat is especially dangerous for vulnerable populations like older people and the unhoused.
Threat level: A 2022 study from Penn State researchers found that 87°F at 100% humidity was the maximum for young healthy individuals to adequately regulate. Another recent study suggests a range between 104°F and 122°F — depending on humidity — is the threshold, NBC News reported.
A person can start developing heat illness at even lower temperatures, depending on age, health, the ability to regularly find relief and the medications they take.
