As the sun beats down and temperatures soar, plenty of tourists were still out and about in the city.
"My sons live here so we're out sight seeing, walking the streets of Philadelphia," said Debbie Aldridge from Des Moines, Iowa.
But most were taking precautions, finding refuge in the shade and drinking lots of water.
Doctor David Targan of Main Line Health says taking precautions is vital and everyone is susceptible to heat-related problems.
Signs of heat exhaustion include:
- Profuse sweating
If that happens, Dr. Targan suggests to hydrate.
"Fluids, fluids, fluids! Get out of the sun immediately and try to cool your body using fans and getting into air conditioning as well," he said.
If the symptoms escalate to heat stroke, sweating will stop, skin will feel hot and dry and confusion sets in. You should immediately call 911.
Dr. Targan says the very young and very old are most at risk. That's especially true for seniors who take certain medications such as a diuretic or some blood pressure pills.
As for exercise, use caution.
"Exercise in this weather is extremely bad. You don't want to be out when the heat is bad and humid," he said.
Instead go very early or alte in the day, or hit the gym.
And for everyone, limit your time outside.
Also, make sure you check on elderly family or neighbors and make sure pets are inside and hydrated as well.
Tips for staying cool and safe during excessive heat
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