Touchless thermometers, also known as non-contact infrared thermometers, quickly measure a person’s temperature without requiring physical contact. These devices function by detecting the infrared energy naturally emitted by the skin, typically focused on the forehead or temporal artery area. The device uses a lens to focus this radiation onto a sensor called a thermopile, which converts the thermal energy into an electrical signal displayed as a temperature reading. This method offers a fast and hygienic way to screen for elevated temperatures, making it a popular choice in public settings and homes.
Preparing for Accurate Measurement
Achieving a reliable reading begins with properly preparing both the device and the environment. The thermometer must acclimate to the surrounding air temperature, often requiring 10 to 30 minutes if stored in a significantly hotter or colder location. Internal components need this time to stabilize, as temperature variations introduce measurement errors.
Before use, visually inspect the sensor lens for any obstructions like dirt, fingerprints, or condensation, as a clean lens is necessary for accurate detection of infrared radiation. Ensure the thermometer is set to the “body” or clinical mode rather than the “surface” mode. The “surface” mode measures the external temperature of objects and will not provide an adjusted human body temperature reading.
Patient preparation is necessary to prevent skewed results from external factors. Ask the person to remove any head coverings, such as hats or heavy hair, and to wipe away any visible sweat or cosmetic products from the forehead. The subject should be tested in an area free from strong air drafts, direct sunlight, or radiant heat sources, as these conditions impact skin temperature.
Step-by-Step Usage Technique
The core technique involves understanding the manufacturer’s specific guidelines for distance and aiming. Start by powering on the device and confirming it is set to the correct unit of measurement, either Celsius (°C) or Fahrenheit (°F). The target area is usually the center of the forehead or the temple area, where the temporal artery is closer to the skin surface.
Hold the thermometer perpendicular to the target area, ensuring it is at the exact distance specified in the user manual, commonly between 1 to 2 inches (3 to 5 centimeters). Holding the device too far or too close causes the sensor to measure an area larger than intended, potentially including surrounding cooler air or other surfaces. Once the device is correctly aimed and held steady, activate the measurement by pressing the scan button.
Wait for the thermometer to process the reading, which usually takes only a second or two and is often signaled by a beep. To check for consistency, take a subsequent reading after waiting at least 15 seconds to allow the skin and the device to stabilize. If the readings are inconsistent, take a third measurement and use the highest of the consistent results.
Troubleshooting Common Accuracy Issues
Inconsistent or unreliable readings are often linked to external variables. A common source of error is measuring a person who has recently entered the testing environment from a significantly different temperature, such as coming inside from cold weather. The body needs a few minutes to adjust to the room temperature before a forehead reading can be reliable.
A low battery can affect the device’s performance, leading to erratic or inaccurate results; replacing the batteries is a simple first troubleshooting step. Sensor contamination is another frequent problem, where a dirty lens or moisture blocks or refracts the infrared energy, causing an artificially low reading. Cleaning the lens with a soft, dry cloth or a cotton swab ensures a clear path for the infrared light.
If the thermometer displays an error code or the readings are persistently outside the normal range, consult the device’s manual for instructions on resetting or recalibrating the unit. While many consumer models are pre-calibrated, mechanical shock or prolonged exposure to extreme temperatures can cause the internal components to drift.
Interpreting the Temperature Reading
The final number displayed must be interpreted in the context of the measurement site. Forehead temperature readings measure surface skin temperature, which is generally lower than core body temperature. A reading from the temporal artery is about 0.5 to 1.0 degrees Fahrenheit lower than a standard oral temperature.
The average normal temperature range taken from the forehead is between 97.6°F and 98.1°F. A reading suggesting a fever, defined as 100.4°F (38°C) or higher, indicates the need for further monitoring or medical consultation. Because forehead readings are easily influenced, a slightly elevated reading should prompt a confirmatory check with a more accurate method, such as an oral or rectal thermometer, especially for infants.
The interpretation of a temperature reading is influenced by factors like the person’s age, time of day, and overall health status. A high reading in an infant, or a very high temperature in any person, should prompt seeking professional medical advice. Understanding which unit (Celsius or Fahrenheit) is displayed is necessary for correct interpretation.