When triple-digit temperatures combine with high humidity levels, heat exhaustion and heat stroke become of significant concern, experts say.
An air quality alert has been issued for the ongoing intense heat wave, which happens when the air quality is predicted to become unhealthy for sensitive groups. Heat indices, which measure the combined impact of heat and humidity on the human body, are expected to exceed 100 degrees.
Dr. Stuart Harris, an emergency physician at Massachusetts General Hospital, explained a few signs and symptoms to watch out for as people try to stay safe.
The first sign to look out for are high body temperatures, which will require cooling the body down. The heart rate often increases, so keep an eye on your pulse. Early signs of heatstroke include dizziness. headaches, nausea and extreme exhaustion.
People are also likely to start feeling confused when overheated, according to Harris, which is why it's important to take note of unusual behavior.
"It typically involves an alteration in mental status - so somebody gets so hot that they're not thinking correctly, they're not interacting in a way that they normally would," Harris said. "That's an indication of a medical emergency and that somebody needs to be chilled very quickly."
Mowing the lawn, delivering the mail, or working in construction, Tuesday’s oppressive heat and humidity made being outside for any extended period of time unbearable.
"It's crazy like I just can’t believe, it's like a wave of heat just blasting at you when you get out of the front door of your house," said Brandon Capers of Worcester.
Runners, walkers and bicyclists were searching for shade for a little bit of a break from the hot sun.
"It's always like 10-20 degrees cooler in the park," said Mark Robie, who was riding his bicycle.
Pet owners were willing to try anything they could to give their four-legged friends relief. Luz Morales, who was walking her dogs Aggie and Molly Morales said, "I'm getting ready to throw them all in the pool."
When extreme heat hits, many animal rights organizations urge people not to leave pets in cars -- even for a short time. Cars quickly heat up to dangerous and even deadly temperatures.
When the outdoor temperature is 95 degrees, it takes only 10 minutes for the inside of a car to reach 114 degrees. Within twenty minutes, the temperature reaches approximately 124 degrees, and in 40 minutes a dangerous 133 degrees. Within one hour of sitting in the sun, vehicles can reach around 140 degrees.
About 700 people die each year due to heat related illnesses, according to the U.S. Centers for Disease Control and prevention.
Boston Mayor Kim Janey's office has reminded residents to stay hydrated, use sunscreen, and limit outdoor activity due to the dangerous heat.
Cooling centers are open at Boston Centers for Youth & Families community centers through Wednesday from 10:30 a.m. to 6 p.m. A full list of centers that will be available can be found at Boston.gov/Heat. The Frog Pond and tot sprays are open at parks and playgrounds throughout Boston, as well as indoor pools. Mirabella pool, which is in the North End, opens Wednesday.