There is also a medium-wave ultraviolet, which is UVB, with a wavelength of 290-320nm, and it is very toxic in sunny weather, so it is easy to cause sunburn. Another is called long-wave ultraviolet, called UVA, wavelength 320-400nm, it wavelength is longer, penetration is stronger, it can cause skin damage, but the toxicity is relatively weak. In the ultraviolet rays we receive, there is more UVA and less UVB, but UVB is more toxic to the human body.
So where is the main toxic effect of light on the skin?
The toxic effects of light on the skin include phototoxic reactions and photomorphic reactions.
Photototoxic reaction: is a non-immune reaction, the role may be photoreceptors occurring energy transfer or under the action of light energy and DNA binding caused. It can be further divided into acute phototoxic reaction and chronic phototoxic reaction.
Acute phototoxic reaction is when a person after sun exposure such as summer activities at the beach, the exposed parts of the bright red spots, edema, and in some cases blistering flaking. It is mainly caused by UVB, often starting minutes to 2-6 hours after exposure to the sun, and reaching its peak after hours to days. Unexposed skin does not cause a reaction.
Chronic phototoxic reaction: is due to long-term repeated exposure to sunlight in the UVB after, resulting in skin wrinkles, flaccidity, surface dryness, roughness or atrophy, hyperpigmentation or hypopigmentation, etc., and even skin cancer.
Photomorphic reaction: light can cause antigenic changes in the body, which in turn leads to skin damage through metamorphosis, sensitizing light is often UVA, and sometimes even visible light. This kind of light damage when the first exposure will not be in a very short period of time, but there is a sensitization period, generally need 1-2 days or longer to react, if the light again, then its reaction time is shortened. The skin manifestations of photomorphic reaction are redness and swelling, the appearance of windburns or pimples, blisters, etc., and rarely hyperpigmentation.
In addition, some people taking some food or drugs containing photosensitive substances after exposure to light can also appear photodamage. Foods that cause phototoxic reactions include mud snails, bamboo lice, gray cabbage, cabbage, radish leaves, spinach, lettuce, fungus, etc.; drugs that cause phototoxic reactions include sulfonamides, tetracycline, chloroquine, etc.
Therefore, intense sun exposure after taking these substances should be avoided.
How should a sunburn be treated promptly?
If it is slightly red, you can use some ice water to apply it directly at home by yourself so that it cools down a bit. If you go to the hospital, you will use some glycerine lotion, menthol and other cool medicine to coat it.