Ultraviolet rays from sunlight, although invisible to our eyes, pose a significant threat to our skin.

Issues such as sunburn, tanning, and various skin diseases, including concerns about skin aging, are closely linked to exposure to these ultraviolet rays.

On Earth, UV radiation is present throughout the year, making sunscreen a necessary item no matter the season. To protect the skin, sunscreen is applied to prevent sunburn and decelerate the progression of skin harm and aging.

The primary purpose of sunscreen is to shield us from ultraviolet rays, specifically UVA and UVB rays. UVC rays are mostly absorbed by the ozone layer, preventing them from reaching the Earth's surface.

UVA rays encompass wavelengths of 320-400nm, constituting long-wave ultraviolet light, while UVB rays fall within the 290-320nm range, characterized as medium-wave ultraviolet.

Sunscreen contains active agents that play a vital role in providing protection. These agents can be categorized into three main types: physical, chemical, and biological. However, the most significant roles are played by physical and chemical sunscreen agents.

In assessing sunscreen effectiveness, two key indicators come into play: SPF (Sun Protection Factor) and PA (Protection Grade of UVA).

SPF primarily reflects a product's ability to prevent sunburn by blocking UVB rays.

PA, on the other hand, gauges a product's capacity to shield against UVA rays.

Presently, available SPF values include SPF15, SPF32, SPF45, and SPF50. In some regions, SPF50+ indicates a higher level of sun protection than SPF50. PA values are denoted as PA+, PA++, PA+++, and the highest level, PA++++.

For instance, SPF15 signifies that the sunscreen extends skin protection to approximately 5 hours (20 minutes multiplied by 15). PA+, representing moderate protection, offers coverage for about 2-4 hours.

Choosing the appropriate sunscreen involves considering three main factors: sunscreen effectiveness, skin type, and usage context. Occasionally, seasonal conditions, personal health, and other factors should also be taken into account.

Sunscreen efficacy primarily hinges on its SPF and PA values, where higher values denote superior protection. Water and sweat resistance is crucial, particularly during activities like hiking or beach vacations.

Additionally, ensure the sunscreen is endorsed by the appropriate regulatory bodies. Verify its approval through official channels to avoid counterfeit products.

Different skin types necessitate tailored sunscreen selection. Neutral skin types can opt for a variety of options, while those with oily skin should prioritize oil control with non-greasy, oil-free formulas.

Dry skin requires moisturizing and nourishing sunscreens, while individuals with sensitive or acne-prone skin should choose purely physical sunscreens devoid of potentially irritating ingredients.

For children and pregnant women, it's advisable to opt for purely physical sunscreens to minimize any potential risks. Infants under two years old are recommended to avoid sunscreen and instead rely on sun protection measures such as umbrellas.

The choice of sunscreen should also factor in the specific context of use. Activities like beach vacations or outdoor excursions with prolonged sun exposure require high SPF (e.g., SPF50) and PA (e.g., PA++++) protection.

For less intense sun exposure, such as daily commuting or indoor work, SPF15 and PA+ are sufficient.

By considering sunscreen expertise, individual skin characteristics, and usage scenarios, you can make an informed choice that effectively safeguards your skin from the harmful effects of ultraviolet rays.