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Relevance: GS Paper III — Science & Technology; Public Health Source: The Hindu, 2026

The Science of SPF and India’s New Sunscreen Standards

1 · What happened

Dermatology experts have flagged a common myth: that a higher Sun Protection Factor (SPF) number means much better protection. In reality, a properly applied SPF 30 can protect the skin better than a poorly applied SPF 100.

For Indian skin and Indian outdoor conditions, doctors recommend a sunscreen with at least SPF 30 plus a PA+++ rating — so the user is protected against both sunburn and skin ageing.

2 · What is the UV Spectrum?

Sunlight is made up of many kinds of rays. The harmful invisible part is called ultraviolet (UV) radiation. UV rays have a shorter wavelength than visible light, which means they carry more energy and can damage the skin. Scientists divide UV rays into three groups based on their wavelength — UVA, UVB and UVC. Each behaves differently when it hits the skin.

Ageing Rays
UVA — Deep Penetration
Longer wavelength. Goes deep into the skin. Causes wrinkles, dark spots and loss of skin elasticity. The PA rating on sunscreen tells you how well it blocks UVA.
Burning Rays
UVB — Surface Damage
Shorter wavelength. Hits the outer layer of the skin. Causes sunburn (redness) and is the main trigger for skin cancer. SPF measures protection against UVB only.
Most Dangerous
UVC — Blocked by Ozone
Shortest wavelength. The most harmful type of UV ray — but the stratospheric ozone layer absorbs almost all of it, so it does not reach the ground.
India’s Answer
BIS IS 17494:2025 + ITA
SPF claims must now be tested through In-Vivo testing (on real human volunteers). The Individual Typology Angle (ITA) is a new scientific scale that classifies darker, melanin-rich Indian skin tones.

3 · What does the SPF number really mean?

  • The basic idea: If a sunscreen says SPF 30, skin wearing it needs 30 times more UV exposure to start burning than bare skin. This test is done under perfect lab conditions.
  • Higher number is not double the protection: SPF 30 blocks roughly 95–97% of UVB rays, SPF 50 blocks 97–98%, and SPF 80 reaches close to 99%. Beyond SPF 30, every extra digit gives you only a tiny extra benefit.
  • The application gap: In daily use, people apply a much thinner layer than the lab uses. So the actual protection on your skin is much less than the number printed on the bottle.
  • Regulator: The Central Drugs Standard Control Organisation (CDSCO) licenses sunscreens as cosmetics. If a sunscreen claims to treat a skin condition (such as severe pigmentation), it is reclassified as a drug and faces stricter clearance.
  • Climate link: India’s heatwaves are getting longer and stronger. Outdoor workers — farmers, construction labour, street vendors — face long UV exposure, making sun protection a serious occupational health issue, not just a cosmetic one.

UPSC Value Box
PA Rating System A Japanese-origin system using + signs (PA+ to PA++++) to show how strongly a sunscreen blocks UVA rays. PA+++ means high UVA protection.
Erythema The medical term for skin redness caused by UVB-induced sunburn. It is the visible reaction used as the endpoint in SPF lab testing.
Photoageing Premature ageing of the skin — fine lines, wrinkles, sagging — caused by long-term exposure to deep-penetrating UVA rays.
In-Vitro Testing Testing done on artificial surfaces in a lab, not on human skin. Cheaper but less accurate — being phased out under the new BIS rules.
Fitzpatrick Scale A Western six-type classification (Type I to VI) of skin based on how easily it burns or tans. Criticised for not capturing the range of Indian skin tones.
Drugs and Cosmetics Act, 1940 The parent law under which CDSCO regulates the import, manufacture, and sale of drugs and cosmetics, including sunscreens, in India.
Bureau of Indian Standards (BIS) India’s national standards body under the Ministry of Consumer Affairs. Sets product standards (like the new IS 17494:2025 for sunscreens) and aligns them with global ISO protocols.
Broad-Spectrum Sunscreen A single product that protects against both UVA and UVB rays — what dermatologists recommend.
UV Index A global 0–11+ scale that reports daily ground-level UV strength. In India, the India Meteorological Department (IMD) issues these forecasts.

MCQ Practice Question
Q. With reference to sunscreen, ultraviolet radiation, and the regulatory framework in India, consider the following statements:

  1. The Sun Protection Factor (SPF) printed on a sunscreen label measures the product’s protection only against UVB radiation.
  2. The PA+++ rating on a sunscreen indicates the level of protection it offers against UVB radiation.
  3. UVC rays are the most harmful part of the ultraviolet spectrum but are absorbed almost entirely by the stratospheric ozone layer before they reach the Earth’s surface.

Which of the statements given above is/are correct?
(a) 1 and 2 only    (b) 2 and 3 only    (c) 1 and 3 only    (d) 1, 2 and 3

Answer: (c) 1 and 3 only

  • Statement 1 — Correct: The SPF number measures only UVB protection — the rays that cause sunburn. Protection against UVA is shown separately.
  • Statement 2 — Incorrect: Swapped. The PA rating measures protection against UVA (the ageing rays), not UVB. Remember: SPF is for burning (UVB), PA is for ageing (UVA). This UVA / UVB swap is a classic Prelims trap.
  • Statement 3 — Correct: UVC has the shortest wavelength and is biologically the most damaging, but the ozone layer blocks almost all of it from reaching the ground.

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