SPF 50 blocks 98% of UVB rays, but UVB is only half the story. UVA rays penetrate deeper, pass through glass, and drive about 80% of visible skin aging. For athletes training outdoors for hours, cumulative UVA exposure is the silent damage that compounds over every session.

Here's how broad-spectrum and PA++++ ratings protect you from the aging rays, why K-beauty sunscreens lead on UVA coverage, and what the HAESKN sunscreen stick delivers in a clear, dermatologist-tested formula.

UVA vs UVB: What Each Does to Your Skin

The sun emits two types of ultraviolet radiation that reach your skin: UVA and UVB. They work differently, and both are dangerous.

UVB rays have a shorter wavelength (280–320 nm). They hit the outer layer of skin and cause sunburn, redness, and direct DNA damage in surface cells. UVB is the primary driver of sunburn and contributes to skin cancer development. SPF measures UVB protection only.

UVA rays have a longer wavelength (320–400 nm). They penetrate deeper into the dermis, where collagen and elastin live. UVA causes wrinkles, sagging, dark spots, and accelerates premature aging. UVA also damages cells in the basal layer of the epidermis, where most skin cancers originate. Research confirms that UVA contributes to and may initiate skin cancer development.

The problem: UVA is present year-round, passes through clouds, and penetrates glass. You're exposed to UVA even on overcast days and indoors near windows. For outdoor athletes, UVA exposure accumulates across the full duration of any outdoor activity regardless of season or visible sunlight intensity. The dose builds even when there's no visible skin response.

Outdoor athletes are exposed to significantly higher cumulative UV radiation than the general population, placing them at increased risk for both melanoma and non-melanoma skin cancers. A 90-minute match at UV Index 8 delivers roughly the same UV dose as three hours at the beach.

What "Broad Spectrum" Means on a US Label

In the US, sunscreens are regulated by the FDA as over-the-counter drugs. Only products that pass the FDA's broad-spectrum requirements can be labeled "broad spectrum". This label means the sunscreen protects against both UVA and UVB rays.

The American Academy of Dermatology recommends only using broad-spectrum sunscreen, as it protects skin more thoroughly from both UVA (which ages skin) and UVB (the rays responsible for burning) rays.

How the FDA Broad-Spectrum Test Works

The FDA uses an in vitro (lab-based) test called the critical wavelength test. The test measures how far a sunscreen's UV protection extends into the UVA range.

Here's the process:

  1. The sunscreen is applied to a PMMA plate (a lab surface that mimics skin).
  2. The plate is irradiated to simulate sun exposure.
  3. The sunscreen's absorbance is measured across the full UV spectrum from 290 to 400 nm.
  4. The critical wavelength is the point at which the cumulative absorbance reaches 90% of the total UV spectrum.

The FDA requires a critical wavelength of 370 nm or greater for a broad-spectrum claim. A higher number means protection extends further into the UVA range.

The catch: Broad spectrum is a pass/fail threshold. A product that scrapes by at 371 nm and one that hits 381 nm both get the same "broad spectrum" label. The US label doesn't tell you how strong the UVA protection is, only that it passed the minimum.

Sunscreens that are not broad spectrum or are broad spectrum but lack an SPF of at least 15 must carry a warning: "Skin Cancer/Skin Aging Alert: Spending time in the sun increases your risk of skin cancer and early skin aging. This product has been shown only to help prevent sunburn, not skin cancer or early skin aging."

The Asian PA Rating System: Measuring UVA-PF

While the US uses a pass/fail broad-spectrum label, Japan and Korea use the PA rating system to quantify UVA protection. PA stands for Protection Grade of UVA. It's a rating scale that tells you how strong the UVA protection is, not just whether it exists.

UVA-PF, PPD, and PA are three ways of rating how well sunscreens block UVA rays, the rays that cause premature aging and long-term skin damage. UVA-PF and PPD give you a number, used mostly in Europe and Asia. PA uses plus signs from PA+ to PA++++, used in Asia.

How PA Ratings Work

The PA system is based on the Persistent Pigment Darkening (PPD) test. This test uses UVA radiation to cause persistent darkening (tanning) of the skin. PPD measures how much UVA exposure is required to create persistent pigmentation lasting 2–4 hours compared to unprotected skin.

In Japan, PPD results are grouped and simplified into PA measurements:

  • PA+: Some UVA protection. PPD factor of 2–4.
  • PA++: Moderate UVA protection. PPD factor of 4–8.
  • PA+++: High UVA protection. PPD factor of 8–16.
  • PA++++: Very high UVA protection. PPD factor of 16 or above.

PA++++ is the highest rating in the Japanese and Korean sunscreen rating system. It indicates a UVA-PF of 16 or higher. Some sunscreens may have a UVA-PF well above 16, but the label still shows PA++++ since there's no PA+++++ category.

PA++++ vs US Broad Spectrum

The US "broad spectrum" label is a minimum threshold, not a rating scale. A broad-spectrum SPF 50 sunscreen could have UVA protection equivalent to PA++ or PA++++. The US label doesn't tell you which.

PA++++ guarantees a high level of UVA protection that broad spectrum doesn't specify. Most Korean sunscreens target SPF 50+ and PA++++ as their standard because Korean regulatory testing is rigorous and consumers expect both high UVB and high UVA protection.

The combination of SPF 50+ and PA++++ means a sunscreen has been tested to offer high protection across both UVB and UVA, which is what you need for genuine broad-spectrum coverage.

Why K-Beauty Sunscreens Lead on UVA Protection

Korean sunscreens are known for lightweight textures, no white cast, and high UVA protection. There are three reasons why K-beauty formulations lead on UVA coverage:

1. Advanced UV Filters

Korea and Japan approve modern filters like Uvinul A Plus, Tinosorb M, Uvinul T 150, and Mexoryl SX. These filters have higher extinction coefficients, meaning they absorb more UV per gram. They require lower concentrations for the same SPF and have lighter molecular structures.

The FDA restricts to older filters like avobenzone, oxybenzone, octinoxate, zinc oxide, and titanium dioxide, which require higher concentrations and heavier formulations.

2. Regulatory Standards

Korea's MFDS and Japan's MHLW require PA testing for UVA protection claims. All sunscreens in South Korea require regulatory approval before they can enter the market, and PA ratings are derived from standardized PPD methods.

Korean and Japanese sunscreens explicitly state PA rating because UVA protection is a regulated requirement. The US does not mandate UVA testing beyond the pass/fail broad-spectrum threshold.

3. Cosmetic Elegance Prioritization

Korean sunscreens market as skincare/makeup hybrid. Consumer expectation is lightweight feel and no white cast. Korean formulations use silicones, film-formers, and volatile carriers that evaporate post-application, leaving a thin protective layer.

Korean skincare culture has long incorporated daily SPF as a routine step rather than a seasonal one. That expectation shaped how Korean brands approached formulation: if people are going to apply it every single morning, it has to be comfortable to use.

Why UVA Protection Matters for Athletes

For outdoor athletes, UVA exposure accumulates across the full duration of any outdoor activity regardless of season, cloud cover, or visible sunlight intensity. The dose builds even when there's no visible skin response. Over a full training season, this cumulative load is significant.

Exposure patterns vary, from intermittent sunburn-inducing training at peak hours to large cumulative exposures, contributing to risk of melanoma and keratinocyte carcinoma. Athletes who train outdoors accumulate significantly more UV exposure than the average person. UVA rays cause long-term skin aging and damage. UVB rays cause burning. Both contribute to skin cancer risk over time.

The cumulative UVA load across a full training season represents meaningful long-term skin damage risk that compounds over a competitive career. For extended outdoor activity, SPF 50 or higher is the consistent recommendation.

Strong UVA protection is arguably more important for long-term skin health than high SPF. UVA rays cause about 80% of visible skin aging (wrinkles, sagging, dark spots). They penetrate deeper than UVB and pass through clouds and glass. You're exposed to UVA year-round, even on cloudy days and even indoors near windows.

How HAESKN Delivers Broad-Spectrum UVA Coverage

The HAESKN sunscreen stick is a clear, FDA-approved chemical sunscreen formulated with K-beauty heritage. It delivers broad-spectrum SPF 50 protection in a stick format designed for one-hand reapplication during high-sweat sports.

Clear Chemical Filters for UVA Coverage

HAESKN uses FDA-approved chemical filters that absorb UV radiation across the full UVB and UVA spectrum. Chemical filters are transparent, which is why the HAESKN stick has no white cast. Zinc oxide is the only single active ingredient that offers excellent protection from UVA and UVB rays, but it leaves a white cast because mineral particles scatter visible light.

Chemical filters absorb UV photons and convert them to heat. The HAESKN formula combines multiple chemical filters to cover the broad spectrum of UVB and UVA, meeting the FDA's critical wavelength requirement of 370 nm or greater.

K-Beauty Formulation Heritage

HAESKN was co-founded by Sherril HwangBo (Creative Director, ex-LVMH) and Eugene Kim (Product Lead, ex-Estée Lauder). Both brought K-beauty formulation standards to the US market: lightweight texture, no white cast, and high UVA protection.

Julio Pina, HAESKN's advisor and an award-winning chemist and formulator, brings expertise in UVA filter chemistry. Chemical filters like avobenzone and octocrylene absorb UVA radiation across the 320–400 nm range. The key is photostability. Filters must remain effective after UV exposure. The HAESKN formula uses film-forming polymers to lock filters in place, even through sweat and water.

Dermatologist-Tested and Water-Resistant

The HAESKN sunscreen stick is dermatologist-tested and water-resistant for 80 minutes. Water resistance claims tell you how much time you can expect to get the labeled SPF-level of protection while swimming or sweating. The FDA requires water resistance testing to prove SPF retention after water exposure.

For athletes training outdoors for hours, the HAESKN stick format makes mid-session reapplication fast. Stick sunscreens fit in a pocket or belt, and you can swipe on more coverage without stopping your run or match.

FAQ

What's the difference between UVA and UVB rays?

UVB rays (280–320 nm) cause sunburn and surface DNA damage. UVA rays (320–400 nm) penetrate deeper, cause aging, and pass through glass. Both contribute to skin cancer risk. SPF measures UVB protection only. Broad-spectrum or PA ratings measure UVA protection.

Does broad spectrum mean the same thing as PA++++?

No. Broad spectrum is a pass/fail label in the US. It means the sunscreen passed the FDA's critical wavelength test (370 nm or greater). PA++++ is a rating scale used in Korea and Japan. It means the sunscreen has a UVA-PF of 16 or higher. PA++++ guarantees a high level of UVA protection that broad spectrum doesn't specify.

Why do Korean sunscreens have PA ratings and US sunscreens don't?

Korea and Japan require PA testing for UVA protection claims. The US FDA only requires a pass/fail broad-spectrum test. Korean and Japanese sunscreens explicitly state PA rating because UVA protection is a regulated requirement. The US does not mandate UVA testing beyond the broad-spectrum threshold.

Is the HAESKN sunscreen stick mineral or chemical?

The HAESKN sunscreen stick is a chemical sunscreen. It uses FDA-approved chemical filters that absorb UV radiation across the full UVB and UVA spectrum. Chemical filters are transparent, which is why the HAESKN stick has no white cast. Mineral sunscreens (zinc oxide, titanium dioxide) leave a white cast because mineral particles scatter visible light.

How often should I reapply sunscreen during outdoor training?

The American Academy of Dermatology recommends reapplying sunscreen every two hours, or immediately after swimming or sweating. For athletes, reapply every 60–90 minutes during high-intensity training. The HAESKN stick format makes mid-session reapplication fast. Stick it in your pocket or belt and swipe on more coverage without stopping.

Does UVA protection matter if I'm only outside for an hour?

Yes. UVA exposure is cumulative. Even short sessions add up over a training season. UVA rays penetrate deeper than UVB and cause long-term skin aging and damage. For outdoor athletes, the cumulative UVA load across a full training season represents meaningful long-term skin damage risk that compounds over a competitive career.

Ready to protect against UVA aging rays? The HAESKN Sunscreen Stick SPF 50 delivers broad-spectrum UVA coverage in a clear, dermatologist-tested formula. No white cast, water-resistant for 80 minutes, and designed for one-hand reapplication during high-sweat sports. Go get it.