Relationship between ultraviolet index and intensity

The unit ultraviolet index is 25mW/㎡ ultraviolet intensity.

Measure the intensity of solar ultraviolet rays with different wavelengths up to 400nm, and multiply the intensity of solar ultraviolet rays with different wavelengths by the corresponding weighted values in the erythema spectrum curve to reflect the response of human skin to ultraviolet rays. Add up the results of the above multiplication to obtain the total ultraviolet intensity weighted by erythema spectrum, and the unit is milliwatts per square meter (MW/m2). Then multiply the total ultraviolet intensity weighted by erythema spectrum by 0.04 to get the ultraviolet index.

Extended data

The ultraviolet index consists of two parts, one is the measured ultraviolet intensity of different wavelengths of the sun, and the other is the ultraviolet dose required for different types of skin to appear erythema after ultraviolet irradiation in medical experiments. The ultraviolet index released to the public is formed by combining these two parts mathematically and then converting them into numbers according to the prescribed standards.

Therefore, the ultraviolet index can be understood as the intensity of the sun's ultraviolet rays reaching the ground and the degree of influence on the naked skin of the human body. The greater the value of the ultraviolet index, the greater the damage to the skin. Medical experiments have proved that the damage of ultraviolet rays to the skin is not only related to the intensity of ultraviolet rays, but also related to the type of skin and the time of sun exposure. ?

Baidu Encyclopedia-Ultraviolet Index Grade

Baidu Encyclopedia-Ultraviolet Index