Non-contact infrared thermometers (NCITs) are handheld devices that determine temperature by sensing the heat naturally emitted by the body, allowing for fast and hygienic use without physical contact. Concerns about safety, especially when used on children, are common, but standard medical NCITs are overwhelmingly safe for general household and clinical use. The primary safety risk associated with these devices relates to inaccurate readings from misuse, not the technology itself.
What Infrared Thermometers Measure
Infrared thermometers function as passive sensors, receiving energy rather than emitting it toward the person being measured. Every object above absolute zero constantly emits thermal radiation within the infrared spectrum. The thermometer’s lens gathers this invisible infrared energy from a target, such as the forehead, and focuses it onto a detector called a thermopile.
The thermopile absorbs the collected infrared energy, converting it into a small electrical signal or voltage. This voltage is directly proportional to the radiation detected, allowing the device’s internal circuitry to calculate the surface temperature. The measurement relies on heat coming from the person, not a beam being shot into the person. This mechanism differs fundamentally from technologies like X-rays or microwaves, which actively project energy.
Addressing Specific Safety Concerns
A common misunderstanding is that infrared thermometers project a harmful beam or pulse into the body. Medical-grade NCITs do not emit radiation that could damage human tissue, skin, or eyes. The technology relies solely on sensing the body’s natural infrared light, which is non-ionizing and harmless. Therefore, repeated use on infants, children, or adults poses no risk of radiation exposure or physical harm.
Some industrial models may include a laser pointer to help the user aim the device from a distance. For medical NCITs, a laser is often absent, but if present, it is a low-power, Class 1 or Class 2 indicator laser. This laser is used only for visual guidance and is not part of the temperature measurement process itself. While users should avoid pointing any laser directly into the eyes, the brief, low-power exposure from a clinical device is not considered hazardous to eyesight.
Ensuring Reliable Readings
While the physical device is safe, the primary operational risk lies in obtaining an unreliable temperature reading that could lead to incorrect health decisions. Accuracy depends significantly on correct usage, including maintaining the proper distance from the person being measured. Most manufacturers recommend holding the thermometer between 1 and 2 inches (3 to 5 centimeters) from the target measurement site, typically the center of the forehead.
Environmental conditions can also distort the measurement. Taking a reading immediately after a person has entered from a cold or hot outdoors environment can skew the surface temperature. It is recommended to allow the person and the device time to acclimate to a stable room temperature before taking a measurement. Furthermore, drafts from air conditioning, excessive sweat, or a dirty lens can interfere with the sensor’s ability to accurately capture the emitted infrared energy.