Infrared (IR) radiation is a type of electromagnetic radiation that lies between the visible light spectrum and microwaves in terms of energy and wavelength. The term "infrared" means "below red," since infrared light has a longer wavelength (and therefore lower frequency) than red light, which is at the end of the visible light spectrum.

Infrared radiation is invisible to the human eye, but we can often feel it as heat. For example, the warmth you feel from the Sun or a fire is largely due to infrared radiation. Anything that emits heat, including living bodies, gives off infrared radiation. That's why infrared sensors can be used for thermal imaging.

Infrared radiation is classified into several sub-types based on wavelength:

    Near-Infrared (NIR): This is the closest to visible light and has wavelengths ranging from about 700 nanometers (nm) to about 1,400 nm. It's used in a variety of applications, including fiber-optic telecommunications and night vision equipment.

    Short-Wavelength Infrared (SWIR): This ranges from about 1,400 nm to 3,000 nm and is used in applications like remote sensing and line-of-sight telecommunications.

    Mid-Wavelength Infrared (MWIR): Ranging from about 3,000 nm to 8,000 nm, this is often used in guided missile technology and thermal imaging.

    Long-Wavelength Infrared (LWIR): This ranges from about 8,000 nm to 15,000 nm and is the main region used by thermal imaging cameras.

    Far Infrared (FIR): This is the farthest from visible light, ranging from about 15,000 nm to 1 mm. It's primarily absorbed by water and can be used in some therapeutic and heating devices.

Infrared technologies are used in a wide range of applications, from remote controls, to thermal imaging, to medical treatments. It's generally safe, but as with any type of radiation, excessive exposure can potentially cause harm, such as thermal burns.

Is infrared harmful to health?

Infrared (IR) light can have both positive and negative effects on health, depending on the dosage, duration, and the wavelength of the light.

Potential positive effects of infrared light include relief from muscle and joint pain, improved circulation, and promotion of general relaxation. In physical therapy and rehabilitation, infrared light therapy is sometimes used to provide these health benefits.

However, excessive exposure to infrared light, especially near-infrared light (NIR), can potentially be harmful. This is because infrared light can heat the skin and especially the eyes. Prolonged or intense exposure can lead to thermal burns or eye damage. Therefore, it is important to take precautions such as wearing sunglasses or staying in shaded areas when spending extended periods in the sun.

In applications like infrared saunas, exposure to infrared light in controlled, low doses is generally considered safe. However, it's always important to consult with a healthcare professional and undergo a medical evaluation before starting any kind of therapy or treatment.