When the sun shines, many people head outdoors. However, neglecting sun protection can lead to excessive exposure of the skin to ultraviolet rays. It’s therefore essential to remember sunscreen with a sun protection factor (SPF) to protect against UV radiation. But what exactly does SPF mean? Which SPF is the right one? And how does sunscreen even work? Here are the answers to these and other questions about sun protection factors.
What Does SPF Mean?
The sun protection factor (SPF) is a measure of the effectiveness of sunscreens and other sun protection products. It is determined worldwide according to the “International Method for Determining the Sun Protection Factor.” The SPF indicates how much longer we can theoretically stay in the sun without getting sunburned, thanks to the sunscreen.
SPF Levels and Protection Categories
The SPF categories, which are listed on many products, provide an initial indication of the protective effect of the various sun protection factors. They roughly classify the protection into four categories:
- Low protection level: SPF 6-10
- Medium protection level: SPF 15-25
- High level of protection: SPF 30-50
- Very high level of protection: SPF 50+
What Sun Protection Factor Should My Sunscreen Have?
Choosing the right sun protection factor depends on several factors. These include skin type, the amount of time spent in the sun, and the intensity of the sun’s rays.
Skin Types and Their Natural Sun Protection Time
To choose the right SPF, it’s essential to first know your skin type. This determines how long your skin can protect itself from the sun with its natural sun protection. Below you will find an overview of the skin types and their respective natural protection times:
- Skin type 1: People with this skin type have very fair skin and very often freckles. Their hair color is reddish to reddish-blond. After prolonged sun exposure, their skin always reacts with a painful sunburn. It does not tan. The skin’s natural protection time is less than 15 minutes.
- Skin type 2: The skin of people with skin type 2 is fair and often shows freckles. Hair color is blond to brown. Prolonged sun exposure almost always results in a painful sunburn. At most, a moderate tan develops after sun exposure. The natural sun protection time is 15 to 25 minutes.
- Skin type 3: This skin type applies to people with light to medium-light skin and dark blonde to brown hair. They rarely get sunburned, and when they do, it is moderate. These individuals tan gradually after repeated sun exposure. Their natural sun protection time is between 25 and 40 minutes.
- Skin type 4: With skin type 4, the skin is light brown or olive-colored, and the hair is dark brown. Sunburn rarely occurs after prolonged sun exposure. The skin tans quickly. It can protect itself for longer than 40 minutes.
- Skin type 5: Skin type 5 is characterized by dark brown skin; the hair of people with this type is dark brown to black. Sunburn is very rare, and no tanning effect occurs after sun exposure. The skin’s natural protection time is longer than 60 minutes.
- Skin type 6: People of this type have dark brown to black skin and black hair. Sunburn is extremely rare for them, and their skin does not tan after sun exposure. Their natural sun protection lasts for more than an hour.
How to Calculate Sun Exposure Time Based on SPF
Sunscreen can extend the skin’s natural protection time, depending on the SPF. The formula (skin’s natural protection time multiplied by the sun protection factor) gives you the number of minutes a person can safely spend in the sun. Therefore, when choosing the SPF, it’s also important to consider how long you plan to be in the sun.
For example, skin type 1 has a natural protection time of 10 minutes. If a sunscreen has an SPF of 30, this means that the skin can be exposed to the sun 30 times longer than unprotected skin before sunburn occurs. The protection is extended to 300 minutes according to the formula mentioned above.
It’s important to know that sunscreens do not provide complete protection from the sun. The Federal Office for Radiation Protection therefore recommends using sunscreens for a maximum of 60 percent of the protection time calculated based on skin type and sun protection factor.
Also Read: Sunburns And Rashes: 5 Remedies To Treat Them
Why Sun Protection Is Important: Skin Cancer and Skin Aging
The sun’s UV radiation is dangerous in many ways; for example, it attacks the genetic material (DNA) of skin cells. If the cells are unable to repair this damage, they can become malignant. The result: tumors and thus skin cancer develop. Ultraviolet radiation also accelerates skin aging and can weaken the immune system, thus hindering the immune response to pathogens. These effects can lead to, among other things, cold sores (caused by the herpes simplex virus).
How Does Sunscreen Work?
To achieve sufficient protection, sunscreen manufacturers often combine several UV filters in their products. Traditionally, organic (chemical) and mineral (physical) filters are used. Here’s how they work:
- Organic UV Filters: Organic filters absorb the sun’s short-wave, high-energy UV radiation and convert it into long-wave, low-energy radiation. To explain: The shorter the wavelength, the greater the risk of the light radiation causing damage.
- Mineral UV Filters: Mineral filters utilize the effect of mineral pigments, which weaken UV radiation by scattering it and reflecting it away from the skin.
- UVA and UVB Protection: The filters mentioned protect against UV-A rays and UV-B rays, or, in the form of broadband filters, against both types of radiation. The latter is important because both types of UV radiation are equally harmful. A UVA label indicates that a sunscreen also offers protection against UV-A rays.
How Much Sunscreen Should You Apply and How Often?
Many people misjudge how much sunscreen is needed to achieve the stated sun protection factor (SPF). An optimal amount is considered to be 2 milligrams per square centimeter of skin. This means that approximately three tablespoons of sunscreen should be applied to an adult’s body. Using only half that amount can reduce the sun protection factor by two-thirds. Ideally, sunscreen should be applied 20 to 30 minutes before sun exposure.
But that’s not all: Sunscreen should be reapplied approximately every two hours. This reapplication is especially important after contact with water and heavy sweating. Even sunscreens labeled as water-resistant are not 100% waterproof. However, reapplying only maintains the effectiveness; it doesn’t extend the duration of protection. Also important: Don’t forget areas like your back, ears, and feet when applying and reapplying sunscreen!
How Long Can You Use Sunscreen?
Sunscreens typically contain preservatives to prevent them from spoiling quickly. To find out more about their shelf life, check the back of the sunscreen: like many other skincare products, sunscreens often have the symbol of an open cream jar. This indicates how many months the product will remain usable after opening.
The shelf life is usually twelve months, provided the sunscreen is stored in a cool, dark place. However, the Federal Office for Radiation Protection recommends not using opened bottles or tubes from the previous year.
Also Read: Sunscreen: Choosing The Right Protection For Outdoor Sports
