Four seas net: sunscreen, it is to point to add the sunscreen that can block or absorb ultraviolet rays to prevent skin from being suntanned and sunburned. Many people are wondering whether sunscreen is useful or not? Is it harmful to the skin? Let's have a look.
The effective time of sunscreen is several hours
The effective time of sunscreen varies according to the SPF value.
The value of sun protection index is applicable to everyone. The calculation method is: assuming that the intensity of ultraviolet light will not change with time, if a person who does not have any sun protection measures stays in the sun for 20 minutes, his skin will turn red. When he uses SPF15 sunscreen, it means that he can extend the time by 15 times, that is to say, the skin will be red after 300 minutes. SPF is a test index to measure the sunscreen's defense against UVB in the sun.
Sunscreen products can effectively resist the damage of UVA and UVB to the skin. If you want to find out how long the sunscreen can protect you, you should first know how long you need to stay in the sun without using sunscreen at all, and then the skin will turn a little reddish; then multiply the required time and SPF value to get the protection time of the sunscreen, and the SPF value marked on the sunscreen is the protection index it provides.
The harm of Sunscreen Spray to skin
Some chemicals in sunscreen spray can increase the risk of skin cancer. According to the latest report of the United States, some sunscreen products may cause endocrine disorders and even skin cancer due to some chemical ingredients. Another study also pointed out that once ultraviolet rays penetrate into the skin and come into contact with these chemicals, it may cause some skin problems. However, the personal care products association of the United States questioned these studies and pointed out that most sunscreen products are tested for long-term safety before they go on the market, which can provide effective protection for consumers.
In this regard, experts said that if the skin care products contain phenol, it will indeed stimulate the skin, accelerate skin aging, and even cause cancer. But in China, most sunscreen products have been strictly tested by the state and will not contain phenol; palmitic acid content is certainly below the national standard. According to the United States recently discovered, Sunscreen Spray ingredients Zinc Oxide, in the sunlight will release harmful particles free radicals, increase the risk of human skin cancer.
A recent study in the United States has observed what changes occur in Sunscreen Spray under sunlight. Experts found that Zinc Oxide, a component of Sunscreen Spray, releases a harmful particle called free radical under strong light. Too much 'free radicals' can damage DNA chains in human cells and cells, leading to an increased risk of skin cancer. Although some unqualified sunscreen spray can increase the risk of skin cancer, it is still very ideal for sunscreen spray to prevent sunburn, but it can prevent ultraviolet rays from violating for the first time. But when choosing a sunscreen spray, a female friend must have a large brand of qualified products and make reasonable use of it.