It is essential that the thermometer lens is perfectly clean to ensure the most accurate results. When the lens of an infrared thermometer is dirty (dust, fingerprints, hair...), less infrared radiation passes through the lens. The results are then underestimated.
Check the condition of the lens
Example of a clean lens
Examples of a dirty lens
Cleaning the lens
Use a cotton swab soaked in 70% alcohol. Gently rub the lens and metal shaft to remove all traces and dirt.
After cleaning the lens, please wait 30 minutes before measuring again.
*credit to Francis of iHealth Labs EU