80%
of UV passes through
cloud cover
100%
UV reflected by
water at some angles
2 hrs
maximum window
before reapplying
98%
of UVB blocked
by SPF50
UV 101

UVA, UVB, UVC —
what's the difference?

The sun emits three types of ultraviolet radiation, but only two reach your skin. UVB is the burn ray — it hits the skin's outer layer, causes sunburn, and is the primary driver of DNA damage that leads to skin cancer. UVA penetrates much deeper into the dermis — it's the ageing ray, responsible for collagen breakdown, wrinkles, and long-term cellular damage. UVA is present at near-constant levels all day, year-round, regardless of season or cloud cover. UVC never reaches us — the ozone layer absorbs it entirely. You need protection from both UVA and UVB. That's why broad-spectrum coverage matters.

UV Ray Penetration Depth
UVB
Epidermis
Penetrates the outer skin layer — causes sunburn & DNA damage
UVA
Epidermis → Dermis
Penetrates deep into dermis — causes ageing, collagen loss, cancer
UVC
Absorbed by the ozone layer — never reaches your skin
🌏 Ozone layer
Acts as a natural shield blocking all UVC. The thinner it gets, the more UVA + UVB intensity increases at ground level.
SPF Decoded

the SPF number
isn't what you think.

SPF measures protection against UVB rays only — not UVA. SPF30 blocks 97% of UVB. SPF50 blocks 98%. SPF100 blocks 99%. The jump from 30 to 50 is marginal — but the jump from "properly applied" to "under-applied" is massive. Most people apply 20–50% of the lab test dose of 2mg/cm², meaning their real-world SPF50 is performing closer to SPF10–15. The number on the bottle matters less than how much you apply, and how often you reapply.

UVB Rays Blocked by SPF
SPF 15
93%
7% in
SPF 30
97%
3% in
SPF 50
98%
2% in
SPF 100
99%
1% in
⚠️ Real-world SPF is significantly lower due to under-application. SPF50 applied at half the dose performs closer to SPF8.
How To Apply

most people apply
way too little.

The lab standard for SPF testing is 2mg per cm² of skin — but in real life, people apply 0.5–1mg/cm² on average. That halves your protection. For your face, that's about a full teaspoon. For your big body parts, fill a shot glass. Apply 15–30 minutes before heading out if using chemical sunscreen — mineral sunscreens like BUUB are effective immediately. And always, always reapply.

🥄
1 tsp
face & neck
🥃
1 shot
big body parts
Apply
before going out
2 hrs
max before reapply
After
swim or sweat
Cloudy Days

clouds don't
block UV. at all.

This is the most common mistake people make. Up to 80% of UV radiation passes straight through cloud cover. You can get a full sunburn on a completely overcast day — and UVA, the deeper ageing ray, penetrates cloud even more efficiently than UVB. Bright visible light and UV radiation are two different things. The sky can look grey and still be blasting you. If it's daytime, UV is present. Full stop.

☁
Nature Inc.™
Cloud Cover
Premium UV Protection System — All-Day Overcast Formula
★★★★★
UV Protection Rating — 1 out of 5
20%
blocked
20%
UV blocked by cloud
80%
UV passes straight through
SPF equivalent 1.25
UVA filtered ~20%
UVB filtered ~20%
Suitable as UV protection No
⚠️
Not recommended as UV protection. Wear SPF regardless of cloud cover.
Reflection & Amplification

water, snow & sand
hit you twice.

Reflective surfaces don't just let UV reach you — they bounce it back at you from below, dramatically increasing your total exposure. Snow reflects up to 80% of UV back upward. Water can reflect 100% at low sun angles. Even sand reflects a quarter of all UV. Surfers, skiiers, and beach-goers are at significantly higher risk per hour than anyone in a park or on a street. Apply more generously and reapply more frequently in these environments.

UV Reflection Meter
⛄️
Snow
80%
🌊️
Water
up to 100%
🏝️
Sand
25%
🌿️
Grass
<3%
⚠️ UV reflection is in addition to direct overhead exposure — not instead of it. At the beach on a sunny day, you may be receiving nearly double the UV dose.
Peak UV Hours

the danger zone
is 10am – 4pm.

UV intensity doesn't track exactly with temperature or light — it peaks around solar noon and remains high for hours on either side. Between 10am and 4pm, UV radiation is at its most intense. Use the shadow rule: if your shadow is shorter than your height, the sun is high enough to cause serious damage. Check the UV Index before heading out — it's available on any weather app. At UVI 8+, even short exposures can cause damage to unprotected skin within 15 minutes.

12am
6am
12pm
6pm
hover
—
UV Index

not all sunscreen
is created equal.

The sunscreen industry uses the words "organic", "natural", and "mineral" loosely. Most products marketed as natural contain the same synthetic chemical UV filters regulators are now questioning. Here's what the science actually says.

Gold Standard
Organic
Mineral
Zinc oxide, certified organic base
✓Physical UV barrier — reflects & scatters UV off the skin surface
✓Full broad-spectrum UVA1, UVA2 & UVB from a single ingredient
✓Photostable — does not degrade or lose effectiveness in sunlight
✓Zero systemic absorption — stays on the skin, not in the bloodstream
✓FDA-certified GRASE — the highest safety classification
✓Certified organic base — no synthetic preservatives or fillers
The only sunscreen type with a clean bill of health from regulators & science.
Mostly Fine
"Natural"
Mineral
Zinc oxide or titanium dioxide, non-organic base
✓Physical barrier — UV filter itself is non-toxic and stays on skin
✓Broad-spectrum coverage — especially zinc oxide
~Base may contain synthetic emulsifiers, parabens, or preservatives
~Titanium dioxide has weaker UVA1 coverage than zinc oxide
~Some nano-particle formulations raise particle penetration questions
✓FDA-rated GRASE — safer than chemical filters
The filter is fine. The base formula varies wildly — always read the full ingredient list.
Cause for Concern
Chemical
Filters
Oxybenzone, octinoxate, avobenzone & others
✗Chemical reaction — absorbs UV and converts it to heat inside the skin
✗Systemically absorbed — detected in blood, urine, and breastmilk within hours
✗Oxybenzone & homosalate linked to hormone disruption
✗Avobenzone degrades in UV light — loses up to 90% effectiveness in 1 hour
✗12 of 14 chemical filters lack sufficient safety data — FDA 2019
✗Oxybenzone banned in Hawaii, US Virgin Islands & Key West — reef toxicity
Widely used, poorly studied. The FDA has requested more safety data. Manufacturers haven't provided it.
FDA 2019 Ruling

It's a big deal,
here's why.

In 2019, the FDA proposed a sweeping update to the regulatory framework for over-the-counter sunscreen. After reviewing the available safety data for every UV filter on the market, the agency made a stark finding: only two ingredients had sufficient evidence to be classified as GRASE — Generally Recognized as Safe and Effective. The remaining 12 were moved to Category III: not enough data to determine safety. The FDA formally requested manufacturers submit the evidence. As of 2024, not a single one has complied. These ingredients remain in products on shelves today, used by millions of people daily.

😉
PS! BUUB is 100% Certified Organic.

That means every ingredient is independently verified — grown without pesticides, synthetic fertilisers, or harmful chemicals. While other brands are still trying to prove their ingredients are safe, ours are certified clean.

2
GRASE — Safe & Effective
The only two UV filters the FDA confirmed safe after a full data review. These are the gold standard.
Zinc Oxide Titanium Dioxide
12
Category III — No Sufficient Safety Data
The FDA asked manufacturers to submit safety data to resolve this. As of 2024, none have.
Oxybenzone Octinoxate Avobenzone Homosalate Octisalate Octocrylene + 6 others
Source: FDA Proposed Rule — Sunscreen Drug Products for Over-the-Counter Human Use (2019). Docket No. FDA-1978-N-0018. fda.gov

the chemical roster
& the red flags.

These are the six most common chemical UV filters. You'll find at least two in almost every non-mineral sunscreen on shelf.

High Concern
Oxybenzone
Benzophenone-3 (BP-3)
What it claims: UVA + UVB filter. One of the most common ingredients in commercial sunscreens worldwide.
The Problem
Absorbed through the skin and detected in blood at levels up to 209 ng/mL — 418 times above the FDA's 0.5 ng/mL safety threshold. Also found in urine and breastmilk. Studies link it to estrogenic activity and hormone disruption. At concentrations as low as 62 parts per trillion, it causes DNA damage in coral larvae.
[1] Matta et al. (2019). JAMA. Blood levels reached 209 ng/mL — far exceeding the FDA's 0.5 ng/mL threshold for additional toxicology studies.
[2] Downs et al. (2016). Archives of Environmental Contamination and Toxicology. Concentrations as low as 62 ppt cause bleaching, DNA damage, and death in coral larvae.
High Concern
Octinoxate
Ethylhexyl Methoxycinnamate (OMC)
What it claims: UVB filter. Widely used for its ability to absorb UV-B radiation and its low cost.
The Problem
Penetrates skin readily and has demonstrated estrogenic activity in animal models — binding to estrogen receptors and altering hormone signalling. Also detected in blood plasma. Banned alongside oxybenzone in Hawaii (2018) for coral reef toxicity. FDA classified it as Category III: insufficient evidence of safety.
[3] Krause et al. (2012). International Journal of Andrology. OMC demonstrated estrogenic activity in mammalian assays, mimicking estrogen binding.
[1] Matta et al. (2019). JAMA. Detected in blood plasma exceeding the FDA's 0.5 ng/mL threshold.
Photodegrades
Avobenzone
Butyl Methoxydibenzoylmethane
What it claims: UVA filter. Often marketed as key for broad-spectrum protection.
The Problem
Inherently photounstable — degrades rapidly when exposed to UV. Studies show it loses up to 50–90% of its UV-absorbing capacity within 1 hour of sun exposure without a stabiliser. To counter this, manufacturers add octocrylene or homosalate — adding more problematic ingredients to fix a core instability.
[4] Hiller et al. (2000). Photochemistry and Photobiology. Avobenzone degraded by 50% within 60 minutes of UV exposure when used alone.
[1] Matta et al. (2019). JAMA. Detected in blood plasma above the FDA's safety threshold.
Hormone Disruption
Homosalate
Homomenthyl Salicylate
What it claims: UVB filter. Commonly used as a stabiliser for avobenzone and primary filter in many SPF products.
The Problem
Detected in blood at high concentrations following application. The EU's Scientific Committee (SCCS) concluded in 2021 that homosalate is not safe at concentrations up to 15% — the current EU maximum. Has demonstrated anti-androgenic activity, interfering with testosterone signalling. Also found in human breastmilk.
[5] SCCS Opinion on Homosalate (2021). Found that the current 15% maximum is not safe based on endocrine-disrupting activity and systemic absorption.
[6] Matta et al. (2020). JAMA. Plasma concentrations exceeded the FDA's 0.5 ng/mL threshold.
Moderate Concern
Octisalate
Ethylhexyl Salicylate
What it claims: UVB filter. Also used to enhance water resistance and stabilise avobenzone.
The Problem
Penetrates skin and is systemically absorbed, detected in plasma following normal use. FDA classified it as Category III. It offers only UVB protection — products relying on it need additional UVA filters, usually the more problematic avobenzone or oxybenzone. May also have weak estrogenic activity.
[6] Matta et al. (2020). JAMA. Among six chemical UV filters detected in blood above the FDA's threshold for required safety investigation.
Free Radical Risk
Octocrylene
2-Ethylhexyl 2-Cyano-3,3-Diphenyl Acrylate
What it claims: UVB filter and photostabiliser for avobenzone.
The Problem
Generates free radicals when exposed to UV — the very thing sunscreen is supposed to prevent. Degrades into benzophenone (a known carcinogen flagged by the FDA) on exposure to light and heat. Detected in human breastmilk. High environmental persistence — found in dolphin and fish tissue.
[7] Manová et al. (2013). Photochemical & Photobiological Sciences. Generates reactive oxygen species (free radicals) upon UV exposure.
[8] Downs et al. (2021). Archives of Environmental Contamination and Toxicology. Detected in human breastmilk samples across multiple populations.
Study References
Matta, M.K. et al. (2019). Effect of Sunscreen Application Under Maximal Use Conditions on Plasma Concentration of Sunscreen Active Ingredients. JAMA, 321(21), 2082–2091.
Downs, C.A. et al. (2016). Toxicopathological Effects of the Sunscreen UV Filter, Oxybenzone on Coral Planulae. Archives of Environmental Contamination and Toxicology, 70(2), 265–288.
Krause, M. et al. (2012). Sunscreens: are they beneficial for health? An overview of endocrine disrupting properties of UV-filters. International Journal of Andrology, 35(3), 424–436.
Hiller, J. et al. (2000). Photostability of UV absorbers. Photochemistry and Photobiology. Avobenzone shown to degrade by up to 50% within 60 minutes of UV exposure without stabilising agents.
SCCS (Scientific Committee on Consumer Safety). (2021). Opinion on homosalate. European Commission. Concluded homosalate is not safe at concentrations up to 15%.
Matta, M.K. et al. (2020). Effect of Sunscreen Application on Plasma Concentration of Sunscreen Active Ingredients. JAMA, 323(3), 256–267.
Manová, E. et al. (2013). Organic UV filters in personal care products in Switzerland. International Journal of Hygiene and Environmental Health.
Downs, C.A. et al. (2021). Octocrylene detected in human breastmilk. Archives of Environmental Contamination and Toxicology.