What Is PA & SFA? Sunscreen Products Guide

PA is a standard for measuring a sunscreen’s ability to protect against UVA rays. It was established by the Japan Cosmetic Industry Association and is widely used across Asia. UVA has a longer wavelength and can penetrate clouds and glass, reaching the deeper dermis layer of the skin. Long-term exposure can lead to:

• Photoaging (wrinkles, sagging, loss of elasticity)

• Pigmentation (sunspots, age spots)

• Increased risk of skin cancer

PA ratings are indicated by plus signs, with PA++++ currently being the highest level, representing extremely strong UVA protection.

SPF is the indicator for UVB protection. UVB has a shorter wavelength but stronger energy, mainly affecting the outer layer of the skin (epidermis). It can cause:

• Sunburn, redness, and peeling

• Short-term skin darkening

• Long-term risk of skin cancer

The SPF number indicates how many times longer your skin is protected from sunburn. For example, if your skin usually starts to burn after 10 minutes in the sun, applying SPF 30 theoretically allows you to stay in the sun for 300 minutes (10 × 30) before burning. However, in reality, the effectiveness can be reduced by sweating, rubbing, or UV intensity. So even with high-SPF products, reapplication is still necessary.

An ideal sunscreen should provide both high SPF and PA ratings to effectively protect against both UVA and UVB rays. Western products often label this as “Broad Spectrum,” meaning they offer protection from both types of UV rays. However, unlike Asian sunscreens, they typically do not clearly indicate a PA rating, so it's important to check the ingredient list when choosing a product.

Sunscreens on the market are mainly divided into two categories: physical (mineral) and chemical. Each type has its pros and cons.

How it works: Uses chemical ingredients (such as Avobenzone, Octinoxate) to absorb UV rays and convert them into heat, which is then released from the skin.

Modern sunscreen products often combine zinc oxide, purified water, hyaluronic acid, and shea butter to create a comprehensive protective system. Each ingredient plays an essential role in sun protection.

Zinc Oxide:

Zinc oxide is the foundation of physical sunscreens, offering benefits on three key levels:

1. Acts like tiny mirrors, reflecting and scattering the full spectrum of UV rays

2. Extremely stable and does not degrade under sunlight

3. Stays on the skin surface without penetrating, making it ideal for sensitive skin

Titanium Dioxide: 

Another mineral that primarily protects against UVB rays and some UVA rays. It works similarly to zinc oxide by forming a physical barrier.

Coconut oil

Contains antioxidants like vitamin E that may provide minor skin-soothing benefits. It can hydrate and soothe skin after sun exposure, potentially aiding in repairing minor damage when combined with other ingredients like aloe vera,

Purified Water: 

Purified water plays a fundamental yet crucial role in sunscreen formulations. It acts as a solvent that helps evenly disperse active ingredients while improving the product’s texture and feel. The right amount of water can reduce the greasy feeling often associated with sunscreens, offering a more comfortable application. As the water evaporates on the skin, it also provides an instant cooling effect, relieving the heat caused by sun exposure.

Hyaluronic Acid: 

Hyaluronic acid offers multiple functional benefits in sunscreen formulas. Known for its exceptional moisture-retention ability, it forms a breathable hydration film on the skin’s surface. This layer not only replenishes moisture lost due to sun exposure but also helps enhance the effectiveness of physical sunscreens by filling the gaps in the skin’s outer layer.

Shea Butter: 

The inclusion of shea butter brings a touch of natural wisdom to this scientific formula. This precious fat derived from Africa is rich in:

• Natural Vitamin E: a powerful antioxidant

• Phytosterols: to help repair damaged skin barriers

• Essential Fatty Acids: for deep skin nourishment

These ingredients work together to create a multi-layered protective system. Zinc oxide shields against UV damage, purified water ensures stability and comfort, hyaluronic acid keeps the skin hydrated, and shea butter offers deep nourishment and repair. This balanced formula combines the precision of modern science with the gentleness of natural ingredients - showcasing the best of contemporary skincare.

Importantly, this formulation is especially suited for Asian skin. It avoids the heaviness of traditional sunscreens and reduces the risk of irritation caused by some chemical filters. Whether used daily in the city or for outdoor activities, it offers comprehensive and comfortable protection.

1. Use Enough: About the size of a HK$1 coin (approx. 2mg/cm²) for the face. Using too little reduces effectiveness.

2. Apply in Advance: Chemical sunscreens need 15–20 minutes to take effect; physical sunscreens work immediately.

3. Reapply Regularly: Reapply every 2 hours, especially after swimming or sweating.

4. Pair with Physical Barriers: Hats, sunglasses, and sun-protective clothing enhance overall protection.