We have characterized the chronic effects of near infrared radiation on human epidermis in vivo and want to compare this with the alterations reported to occur after UV irradiation.
We studied 8 normal healthy volunteers (4 men, 4 women, age range 28-39 years; skin phototypes I through III) with no history of skin disorders and minimal solar damage.
An infrared lamp (Hydrosun 500; Hydrosun Medizintechnik GmBh, Germany) with single-output band (620-1370 nm) and an irradiance of 440 mW · cm−2 was used. Irradiance between 250 nm and 400 nm is 0.0034 mW · cm−2, but from 250 nm to 340 nm is only 0.00045 mW · cm−2, 106 less than the main infrared band; 9.5 minutes' irradiation at 30 cm is equivalent to a 1-hour exposure to a typical solar spectrum (ASTM).1
Edwards C, Gaskell SA, Hill SA, Heggie R, Pearse AD, Marks R. Effects on Human Epidermis of Chronic Suberythemal Exposure to Pure Infrared Radiation. Arch Dermatol. 1999;135(5):608-609. doi:10-1001/pubs.Arch Dermatol.-ISSN-0003-987x-135-5-dlt0599