A heat wave has hit the U.S., and a deadly one at that. The National Weather Service Prediction Center in College Park, Md., said 107.5 million people are affected by a combination of heat advisories, excessive heat warnings and excessive heat watches across the country.

According to PBS, the heat wave set record temperatures in the West, Southwest and Denver over the past weekend and moved east to the Gulf Coast and the Carolinas. In Milwaukee, two people died as southeast Wisconsin saw its warmest temperatures in a decade. One 39-year-old woman perished in her home Tuesday night. The temperature in the house was 88 degrees and her core temperature was 101 degrees, said the Milwaukee County Medical Examiner’s office. The second individual was an 89-year-old man who was found collapsed in the backyard. The Milwaukee Health Department urges people to know the signs and symptoms of heat exhaustion and heat stroke, such as dizziness, nausea, extremely high body temperature and rapid pulse.

In Kansas, thousands of cattle have perished in recent days due to excessive temperatures and humidity,  says the New York Post.  The deaths add more pain to the U.S. cattle industry as herds have suffered from drought and also lack of feed due to Russia’s invasion of Ukraine which has reduced global grain supplies.

Experts say people should be extremely careful during this heat wave. According to the Centers for Disease Control and Prevention (CDC), more than 600 people in the U.S. are killed by extreme heat every year. Their helpful web page offers tip on how to prevent heat related illness in the most vulnerable groups such as the elderly, infants, and children, and those with chronic medical conditions.

“When the heat safety index is too high and exposure to heat is too lengthy, heat-related illness often occurs,” says Anthony Abbott, an internationally recognized expert in exercise physiology and the founder, president, and chief instructor for Fitness Institute International.

“The young, the elderly and those with certain medical conditions and comorbidities are more vulnerable from physical harm to the heat,” he says. “Many people are unaware that children are less efficient in their heat dissipation response in comparison to adults, and therefore require greater supervision when exercising or playing outdoors during the summer months.”

Everyone, regardless of age or health, should follow the CDC’s recommendations for preventing heat-related illness:

• Wear appropriate clothing. Choose lightweight, light-colored, loose-fitting clothing.

• Stay cool indoors. Stay in an air-conditioned place if possible. If your home does not have air conditioning, go to a mall or public library. Even a few hours spent in a cool environment can help your body stay cooler when you return to the heat. See if your local health department has set up any heat-relief shelters near you. Electric fans will not prevent heat-related illness when the temperature soars in the high 90’s. You are better off taking a cool shower or bath.

• Schedule outdoor activities carefully. Limit your outdoor activity to when it is coolest, like early morning or evening. Rest often in shady areas so your body has a chance to recover. Instead of running or hiking, try swimming or biking because the water and wind can keep you cool.

• Pace yourself. Cut down on exercise during the heat wave. If you are not used to working out or exercising in a hot environment, start slowly and stop if you feel lightheaded or short of breath.

• Wear sunscreen. Always protect your skin with sunscreen before going outdoors and wear a wide-brimmed hat and sunglasses as well. Look for sunscreen that says it is broad-spectrum or offers “UVA/UBV protection” on the label.

• Stay hydrated. “Water is usually the drink of choice, however, with extended activity coupled with profuse sweating, sports drinks may be preferable due to the availability of their electrolytes,” says Abbott. Don’t wait until you are thirsty to drink. If you take a diuretic, check with your doctor about how much you should drink.

• NEVER leave infants, children, or pets in a parked car. Vehicles can quickly heat up to dangerous temperatures even with windows open. Always check your car thoroughly when you exit to ensure no sleeping child or pet has been left behind.