A. The use of an infrared scanner can be very tricky and requires fundamental knowhow of how IR non-contact thermometers work. Without proper guidance, a non-contact thermometer may produce a false reading. There are six basic rules to remember while trying to use a non-contact IR thermometer: 1. An IR thermometer scans radiation from the exposed area of the skin which can be the forehead, teardrop, fist, or wrist, etc. 2. Fever is defined as a rise in core body temperature above 100.4F. Skin temperature rises with increasing core body temperature only if the skin is not exposed to extreme hot or cold environment. The best ambient to scan is always between 20C and 30C (70-90F) or indoor ambient. Also, different areas of the skin differs from the core body by a constant amount. For example, the forehead will be 1-2F less than the core body while for the fist, the difference is slightly larger ~ 1-4F. But if a person is exposed to windchill and forehead/fists are not covered, then this difference between skin and forehead can exceed more than 10F. 3. Skin below which there are arteries (better blood circulation) are the closest to core body temperature and therefore are more preferred areas for scanning since blood carries the heat from the body to the skin. 4. However, since fever screening devices are used mostly to screen the people who are walking from the parking lot to a nearby reception area, the best area of the skin to scan is the middle of the forearm since that is normally covered during winter. 5. Reading will be consistent and good if the sensor is within 4-6 inches. Beyond this range, reading will be unreliable due to bad signal to noise ratio. 6. It is advisable to calibrate the non-contact thermometer with a NIST traceable standard blackbody radiator for better reading.