How accurate are infrared thermometers? FOX13 puts them to the test

Watch: How accurate are infrared thermometers? FOX13 puts them to the test

MEMPHIS, Tenn. — Temperature checks are part of our new normal as we navigate the COVID-19 pandemic.

Many restaurants, hospitals, and small businesses are using no-contact infrared thermometers to check your temperatures before you walk inside.

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The FDA says these infrared thermometers are a pretty effective way to check someone’s skin temperature while maintaining social distancing. But the government agency warns these thermometers have some limitations.

From the nail salon to your favorite restaurant to the county government building, many of us have had our temperatures checked by infrared thermometers before we can enter many businesses.

The FDA says these devices measure skin surface temperatures, which is lower than taking your temperature orally.

But how accurate are these devices?

FOX13 Investigates decided to put them to the test. We bought three different infrared thermometers at various price points from $25 to $65.

With help from Dr. Sharon Little, an assistant professor at the UT Health Science Center College of Nursing, we tested each one.

We started the session by checking Kirstin Garriss' temperature with an oral thermometer. Dr. Little said this is the most accurate of the thermometers we had.

“It’s going to wait until it gets to a certain level for a certain period of time before it reads it, because if it’s going up and down or going up ever so slightly, then it’s going to continue to try to obtain the temperature,” said Dr. Little.

Little said normal temperatures for adults range from 97 to 99 with the generally accepted norm of 98.6.

Since Kirstin exercised a few hours before the interview, Dr. Little said her temperature of 99.5 was considered normal.

“It definitely goes up with more activity. The temperature warms up, and we are more active, it can go up,” said Dr. Little.

FOX13 tested each infrared thermometer. We got similar readings from the I-Health thermometer and Dr. Talbot’s non-contact infrared thermometer.

Both were fewer than two degrees from Kirstin’s internal temperature. But the first thermometer was the least expensive and had the lowest reading. It was almost three degrees lower than the internal temperature.

Dr. Little said there are various reasons why your skin surface temperature may vary, including the weather.

“If it’s very warm outside or sometimes even just getting into cars. Cars can be kind of warm, and if you haven’t had a chance to kind of cool down for that it can also affect your temperature and make your reading be inaccurate in terms of it being falsely elevated,” said Dr. Little.

She suggests taking a moment to let your body rest before going into a business or store if you’re getting out of a hot car.

Dr. Little said wearing your mask shouldn’t affect your temperature.

“Just because you feel warmer doesn’t mean your temperature has gone up,” said Little.

She said these thermometers are a good way to screen for temperatures quickly, but they are not a silver bullet.

“Of course, that’s not going to get everyone because a third of people are going to be asymptomatic, which means they won’t have a fever or their temperature won’t be elevated and may not have some of the other symptoms,” said Little.

The FDA said these devices are not effective when taking the temperature of multiple people at the same time.

The agency said these infrared thermometers shouldn’t be used for what they call “mass fever screening.”

The FDA also said make sure you’re aiming the device properly, so it picks up the most accurate reading.

Memphis Restaurant Association president Ernie Mellor said the organization isn’t recommending certain types of thermometers to check employees and guests under the COVID-19 restrictions.

Mellor said he hopes all members are being compliant on all levels especially checking for fever.