CHICAGO (CBS) — A medical company is screening more than 100 construction workers a day for COVID-19, but Amphibious Medics is using thermometers meant to take the temperature of air vents, not people.

A former Amphibious Medics employee told CBS 2 his fears about these readings.

“We don’t want to see these people going home to their families, and say somebody was screened yesterday, and they were given the go-ahead, and it’s because of this misuse of these thermometers. They can carry it home to their families,” Anthony Guazzo said.

A supervisor at Amphibious Medics said the industrial thermometers can be off by two or three degrees. Several doctors said that can make a significant difference in accurately detecting a fever.

The labels for the products also state they should not be used as precision thermometers.

Since they test at more than 10 construction sites in Chicago, we asked Amphibious Medics if they’re planning to do more accurate readings.

The Chief Executive Officer of Amphibious Medics later told CBS 2 that medical grade contactless thermometers are currently in short supply, but as they become available, the company will phase out its industrial thermometers.

To account for any imprecise measurements until then, Amphibious Medics instructs employees to add two degrees to each reading. Any worker with an irregular reading will partake in a mandatory secondary screening, in which a precision thermometer is used.