COLUMBIA, S.C. (WOLO) -- It's no secret, the heat is on!

While outside on Wednesday, you may have noticed more than just the temperature. Instead, you may have seen a haze over the city.

It's called ground level ozone, but what causes it?

"Vehicle emissions, the exhaust that comes out of the cars that we drive, will literally go up into the sky and cook under the hot temperatures of the sun, and that's what causes ground level ozone," says DHEC Spokesperson Thom Berry.

When there's too much ground level ozone, DHEC will issue an ozone warning.

"Whenever we issue an ozone alert, it is generally targeted at those people who have breathing difficulties who may have a lung condition or a respiratory condition that affects there ability to breathe," says Berry.

So what should you do to avoid danger?

Stay inside, or if you have to be outside limit your outdoor activity to the early morning or late afternoon hours and drink plenty of fluids.

This are things Stephanie Hunter took into consideration at the park on Wednesday with her two children, Joseph and Albert.

"I make him take like 30 minute breaks and if it gets too bad out here, we will cat it a day at the park", says Hunter.