Use of infrared thermometers and thermal imagers for COVID-19
Non-contact infrared thermometry systems (infrared thermometers and thermal imagers) are being increasingly used to measure skin temperature as a proxy for core body temperature as a means to detect people with fever associated with COVID-19 (as they were with the SARS epidemic in 2003).
The Measurement Standards Laboratory of New Zealand (MSL) has expertise in the field of infrared thermometry and can comment on technical aspects related to the measurement process, but not on the clinical implications.
To ensure the reliability of measurement results, all measurement systems must be calibrated against a reference standard that is traceable to the International System of Units. In New Zealand, MSL and a handful of second-tier calibration laboratories are accredited by International Accreditation New Zealand (IANZ) to perform the calibration of infrared thermometry systems. These laboratories can be found on the IANZ website (https://www.ianz.govt.nz/(external link)). Instrumentation imported from overseas should either be calibrated by an IANZ-accredited laboratory or should have a calibration certificate provided by a similarly accredited laboratory in an overseas country.
Calibration is only the first part in assuring reliable measurements with infrared thermometry systems. Readings can be affected by environmental conditions, measurement distance, and physiological properties of skin related to blood flow and presence of surface moisture (sweat). These issues can cause the readings to be both falsely high and falsely low. Thus, while infrared thermometry systems may provide a useful screening tool, it is unlikely that these measurements alone can reliably detect people with fever. Any suspected case should always be verified by a qualified person using a clinical thermometer.
For more information, a study made by the Spanish national metrology institute can be found here(external link).
We encourage you to contact us if you want to know more about the reliable and accurate use of these thermometers.
Dr Peter Saunders is internationally recognised as a leading authority in radiation thermometry and is NZ’s foremost expert. He has worked in this field for more than 25 years and has provided advice to many industries to find solutions to difficult temperature measurement problems.