How much UPF is enough? How to choose and care for it? A comprehensive review of sun protection clothing

Tuchong Creative

What we usually call sun protection refers to protection against sunlight ultraviolet radiation. The wavelength of sunlight ultraviolet rays that can usually reach the ground is 280-400 nanometers. Ultraviolet rays with a wavelength between 280-315 nanometers are called sunlight ultraviolet UVB. Ultraviolet rays with a wavelength between 315-400 nanometers are called sunlight ultraviolet UVA. UVA has strong penetrability and can easily damage our dermis, causing tanning. UVB can cause sunburn. When sunlight passes through the atmosphere, most of the UVB will be absorbed, and most of what reaches the ground is UVA. Therefore, in the national standard GB/T18830-2009, the individual evaluation standards for anti-ultraviolet products clearly stipulate that the main things that need to be assessed are the ultraviolet protection factor UPF and UVA values. UPF mainly refers to the ratio of the average benefits of ultraviolet radiation in the absence of protection and with protection. The national standard stipulates that products with a UPF greater than 40 and a UVA less than 5% can be called anti-ultraviolet products.

No matter how expensive the sun protection clothing is, the implementation standard is GB/T 18830--2009 "Evaluation of UV protection performance of textiles". As long as it meets the standard, there is no need to worry about the sun protection ability. So how does the sun protection clothing on the market implement the national standard?

We selected ten brands of sun protection clothing based on the hot-selling lists of sun protection clothing on major online shopping platforms. Their prices ranged from 100 to 300 yuan. In addition, we also purchased a sun protection clothing that only cost a few dozen yuan but sold more than 200,000 units.

In order to ensure the fairness of the test, the sun protection clothing we purchased were all gray. We took eleven samples to the Zhejiang Institute of Quality Science and Technology and conducted UV performance tests in a professional laboratory. According to the national standard, we need to test the two data of UVA and UPF.

Let's first look at the UVA test results. The unbranded but very popular sun protection clothing purchased for 25 yuan on the 11th has a UVA value of 12.10%, far exceeding the national standard of less than 5%. The UVA values ​​of the other ten sun protection clothing all meet the national standard, among which No. 1, No. 4, No. 9, and No. 10 are all less than 1%, which is excellent in filtering long-wave ultraviolet UVA.

How is the UPF test result? Except for No. 11, whose UPF value is only 24, far below the national standard of 40, the other ten sunscreen clothing are all above 40, and the data of No. 2 and No. 4 are far above 40, reaching more than 900. No. 11's UVA and UPF do not meet the national standard requirements and cannot be considered a sunscreen product.

Theoretically, the larger the UPF value and the smaller the UVA value, the better the sun protection effect. In daily life, a UPF greater than 50+ is sufficient. UPF40+ can block more than 97.5% of ultraviolet rays, and UPF50+ can block more than 98% of ultraviolet rays. Such sun protection effect is sufficient. Therefore, a UPF value that is too high is meaningless.

After testing, the ten sun-protective clothing on the best-selling list all meet the national standards, so you don’t have to worry about their sun-protection effect. However, they must also be breathable and comfortable while providing sun protection, so many sun-protective clothing have some mesh designs, especially for areas such as the armpits and back that are prone to sweating. Will the mesh design affect their sun-protection effect? ​​We also conducted UV performance tests on the mesh of these six sun-protective clothing with mesh designs, namely 1/3/5/7/8/10.

Among them, the UPF and UVA of the mesh of No. 5 sun protection clothing do not meet the national standards, and there is almost no sun protection effect. Although the data of the other five models are not as good as those of ordinary sun protection fabrics, the mesh of them all meet the national standards.

The mesh is designed for better ventilation. We can see under the light that the mesh is more transparent than ordinary sunscreen fabrics. In theory, the better the breathability, the worse the sunscreen performance, but through experiments, most of the mesh with better breathability also meet the national standards, so don't worry.

In addition to sun protection and breathability, many sun protection clothes now use cooling technology.

What we usually call cool fabrics are fabrics that can quickly take away the heat from the skin the moment it comes into contact with the skin. The advantages of cool fabrics are mainly reflected in two aspects. One is that they have good thermal conductivity and can quickly take away body temperature. The other is that they have good moisture conductivity and can quickly conduct sweat away from the surface of the clothes. In the national standard, there are also special standards for "coolness" to be considered.

According to the national standard, a fabric can only be called a cool fabric if its instantaneous coolness is greater than or equal to 0.15 joules per square centimeter second. The larger the data, the more obvious the coolness and the better the cooling effect. Through testing, the coolness data of the ten sunscreen jackets were all greater than 0.15 joules per square centimeter second, with No. 5 being the lowest, and No. 10 having the best data and a more obvious cooling effect.

Will the sun protection effect of sun protection clothing decrease due to washing and years of use? How should it be cared for on a daily basis?

Sun protection clothing must take into account the sun protection function, and some additives will be used, and there will be some changes in the process. Long-term washing or multiple washing will destroy the additives or process of the sun protection clothing, reducing the sun protection effect. In order to avoid the above situation, when washing sun protection clothing, first avoid rubbing vigorously. Secondly, do not use overheated water to wash. Finally, do not use bleach.

What should you pay attention to when buying sun protection clothing?

First, look at the tag, that is, choose the one with all three labels. Second, look at its sun protection index to see whether its implementation standard meets the national GB/T 18830-2009 standard. Third, when you can touch the sample, choose the fabric that feels soft and has a noticeable cool feeling when it touches the skin. Fourth, look at the fabric of the product. Choose a fabric with a tight texture, a slight thickness, and a slightly darker color.

This article is a work supported by the Science Popularization China Creation Cultivation Program. Author: Curious Lab

Reviewer: Zhang Na, Associate Researcher, Doctoral Supervisor, Peking University School of Public Health

Produced by: China Association for Science and Technology Department of Science Popularization

Producer: China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.