Comparing the temporal artery location figure we show earlier, the principle and characteristics of temperature measurement and some techniques introduced earlier, it’s not hard to know why the IR gun is inaccurate. First, the temporal aorta is located 2 mm beneath the skin surface on both sides of the forehead, while behind the center of the forehead is small branches of the temporal artery, and they are deeper  beneath the skin surfaces the picture shows.

Secondly, measuring the temperature by aiming at the center of the forehead stand still does not necessarily “hit” the temporal artery, the heat source we want to measure, .

Thirdly, there is a 4cm distance between the sensor and the forehead, and the ambient temperature will have a great impact on the thermal energy emitted by the forehead. These are the main reasons why the IR guns are  not accurate. Mothers who have already bought IR guns should replace them with more accurate thermometers for the health and safety of their children. The existing IR gun may be used to measure the temperature of the baby’s bath water, give it something that they can do.