Summer sun protection knowledge

Every summer, sun protection is a common topic, but despite this, there are still many people who do not understand basic sun protection knowledge.

Sun protection, mainly to prevent ultraviolet rays that are invisible in the sun. Ultraviolet rays are part of the electromagnetic spectrum of solar radiation and are divided into UVA (400-315nm), UVB (315-290nm) and UVC (290-200nm) according to the wavelength. UVA is further divided into UVA1 (400-340nm) and UVA2 (340-315nm). 95% of the ultraviolet rays that reach the earth are UVA, because all UVC and most UVB are absorbed by oxygen and ozone in the atmosphere, and ultraviolet rays with a wavelength of less than 290nm cannot be detected on the earth’s surface.

Generally speaking, white people tend to tan after sunburn. For people with darker and darker skin, especially Asians, there is generally no erythema reaction before tanning, and they basically darken silently.

Four types of people need to pay more attention to sun protection

Patients with photosensitivity diseases: systemic lupus erythematosus, dermatomyositis, solar skin diseases (multitype solar eruption, chronic actinic dermatitis, solar urticaria, acne-like vesicular disease, xeroderma pigmentosum, etc.).

Elderly people: Avoid direct sunlight, especially at noon, so as not to induce skin tumors.

Ordinary young people: avoid tanning and sunburn and prevent photoaging.

Patients after laser and chemical skin resurfacing: avoid anti-black after laser surgery.

Do I still need to put on sunscreen after using an umbrella, wearing a hat, etc.?

Of course, it is necessary to choose a sunscreen with a relatively small sun protection index, because although an umbrella or hat can block the sun, the ground, grass, water, and snow can all reflect ultraviolet rays to varying degrees. Generally, the ultraviolet light reflected by grass is 1%, the ultraviolet light reflected by the water surface is 20%, and the ultraviolet light reflected by the snow is 80%.

Choose physical sunscreen or chemical sunscreen?

Physical sunscreen: reflect ultraviolet light through a layer of inert metal particle film, usually zinc oxide or titanium dioxide plays a role to reflect ultraviolet light, so that ultraviolet light does not touch the skin. Generally, this kind of sunscreen is less irritating and will not be absorbed by the skin. It is the first choice for sensitive skin, but it will whiten after application and affect the appearance.

Chemical sunscreen: Absorbed sunscreen products absorb UVB and UVA or two kinds of ultraviolet through special chemical substances, and then emit them in the form of heat. The sunscreen effect is mainly determined by the chemical structure. Generally, the skin can be selected and applied. After application, there is no whitening phenomenon, which is more natural.

How to distinguish between physical sunscreen and chemical sunscreen?

How to distinguish between physical sunscreen and chemical sunscreen mainly depends on the composition of its sunscreen ingredients. Generally, sunscreens containing titanium dioxide and zinc oxide are physical sunscreens, and other ingredients are chemical sunscreens. In addition, physical sunscreens have poor air permeability and whitening, which is difficult for general consumers to accept.

How to choose sunscreen index?

Solar protection index (SPF): generally 10 to 50, mainly protects against UVB, the higher the value, the stronger the protection ability

UVA protection index (PA): generally + to ++++, mainly protects UVA, the more the plus sign, the higher the protection ability.

How to apply sunscreen?

Application time: 20-30 minutes before going out.

Replenishment time: general physical sunscreen is refilled every 3-4 hours, chemical sunscreen is refilled every 2-3 hours

Facial smearing area: the entire face is about the size of a one-yuan coin or a unit between fingers (from a 5mm inner diameter medicine tube, squeeze a section of ointment, just to reach the length of the distance from the end of the index finger to the horizontal line of the distal interphalangeal joint Dosage) Apply two palm areas.

Do you know what to do after sunburn?

Mild ones (only erythema, no blisters or erosions): Use a towel to wrap the ice and apply ice, and do not directly touch the ice to avoid frostbite. Or use calamine lotion three times a day.

Severe cases (erythema, edema, blisters, erosions, etc.): oral antihistamines or even small doses of hormones, in addition to the above methods, external glucocorticoids, indomethacin solution and other anti-inflammatory.