return the syringe to the doctor so she can tell us about spf creams, what spf creams are needed, lina dmitrievnahis is ultraviolet. which penetrates deep into the skin and destroys alosin collagen. let's show how this happens. so, we have two types of rays: type b rays and type a rays. type b rays can burn the skin and stimulate the production of melanin, which gives our skin a tan, this is a brown pigment, but they do not penetrate deeply, these are safe rays. you see, the skin is tanned under the influence of type b rays, type b rays. but they penetrate deeply, they cut collagen and alosni, so our task is to prevent them from penetrating, which is what we do, so in the summer you need to apply spf +50 cream to protect your skin from ultraviolet radiation and protect your collagen and elastin, this is a must, and we will now show how the rays are reflected from the spf cream, they simply do not penetrate the skin, so this must be done, in general. always, the cream should always be, except spf 50+, that is, above 50, starting from 50, the inscription ppd. what does this mean, elina dmitrievna?