To be accurate, infrared thermometers must be kept free of dirt, dust, moisture, fog, smoke, and debris. Always take the time to clean your infrared thermometer after exposure to dirty, dusty, smokey, or humid conditions. You should also plan a regular cleaning every six months or so. Particular care should be taken to keep the infrared lens and tunnel clean and free of debris.
To clean your infrared thermometer:
Dip a soft cloth or cotton swab in medical alcohol (never use soap or chemicals).
Carefully wipe the lens first and then the body of the thermometer.
Allow the lens to dry fully before using the thermometer.
Never submerge any part of the thermometer in water.