The day, which became the hottest of 2011 so far, was forecast to have an unhealthier air quality at Code Orange, which applies to sensitive groups such as children, the elderly and asthmatics.
"It affects all of us, depending on how much we're out in it," said Alan Giles, a senior air quality specialist with Mecklenburg County.
Giles was working at one of the county's seven air monitoring sites. Located at Garinger High School, it can monitor everything from wind speed to the size and concentration of pollutants in the sky. But Giles said the most critical information is how much ozone there is.
Most people think of ozone as a layer high in the Earth's upper atmosphere protecting humans from dangerous ultraviolet rays from the sun. Giles said the ozone layer is good, but when it's closer to the ground in the air that humans breathe, it can damage respiratory systems. He said that's why it's watched on a daily basis in Mecklenburg County.
"We've got a monitor right here, and it's showing 80.1 parts per billion, and when I got here 15 minutes ago, it was 69 parts per billion," he said.
Giles said if the number averages 75 or higher during any eight-hour period, the air quality warning jumps to the Code Orange level.
Dr. Charles Bregier Jr. at Presbyterian Urgent Care said that's why Tuesday was a double whammy: The potential existed for not just high ozone, but also the highest temperatures for the Charlotte area in months.
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"Our bodies are not acclimatized to it yet," he said. "So if you're not used to the heat, you really don't know what to do from a cardiovascular perspective."
Bregier explained that after a couple weeks of consistent heat, the body physically adapts so it's optimized to cool off. It's why he said anyone outside should pay attention to warning signs like thirst and dizziness, especially in the early part of the summer season.
Construction worker Matt Underwood took that message to heart.
"I just take plenty of breaks and especially drink a lot of water (to) stay hydrated," he said. "It can be a challenge at times."
Wednesday: Sunny and very hot. A Code Orange ozone aleat has been issued. Highs in the middle 90s. Thunderstorms will start firing up by the late evening hours. Wednesday evening: A few storms possible through the evening. Otherwise partly cloudy with lows near 70. Thursday: Still hot with highs in the mid 90s and just a small chance for a pop up storm in the afternoon. Friday: Computer models hint at a chance at a few storms for some but it will be hot for all with highs around 90. Saturday: More grilling from Mother Nature with highs in the mid-90s. Sunday: The heat wave rolls on with little threat of rain to cool you off. Highs in the mid-90s.