UV radiation in the car: what the science says and how to protect your skin

19.10.2026

This article brings together what health bodies and published studies say about ultraviolet radiation, the skin and the car. Every claim carries its source, numbered at the end.

In short

The World Health Organization's International Agency for Research on Cancer (IARC) classifies ultraviolet radiation as carcinogenic to humans — Group 1, the same group as tobacco and asbestos.¹
According to the IARC, 83% of new melanoma cases worldwide in 2022 were attributable to UV radiation.²
Car windows, especially the side ones, let part of the UVA rays through, and UVA reaches the deep layers of the skin.^4,5,6
A certified automotive film cuts the UV coming through the glass by more than 99%.^9,P

What UV radiation is

The sun gives off three kinds of ultraviolet radiation.¹

UVC (100–280 nm) — stopped by the atmosphere; it does not reach the ground.
UVB (280–315 nm) — causes sunburn; glass stops most of it.⁴
UVA (315–400 nm) — does not burn, but goes deeper, down to the dermis.⁷ It is also the kind that passes through glass.^4,5

UVA is there all year, from morning to evening, in sun or cloud. You cannot feel it: it neither warms nor stings. That is why almost nobody counts it.

What the science has established

UV radiation causes cancer. In 2009 IARC experts classified all ultraviolet radiation — UVA, UVB and UVC — as carcinogenic to humans, the top category of the scale. Solar radiation had been there since 1992.¹

Melanoma is the most serious case. In 2025 the IARC published its latest estimate: of about 332,000 new melanomas worldwide in 2022, about 267,000 — 83% — were due to UV radiation.² According to the WHO, excessive UV exposure also causes more than a million cases a year of other skin cancers.³

UVA contributes directly. UVA reaches the dermis and is associated with skin ageing.⁷ Studies indicate it accounts for much of the immunosuppression caused by the sun — the weakening of the skin's defences against damaged cells.⁸

The eyes suffer too. The WHO estimates that about 10% of cataract blindness worldwide may be due to UV radiation.³

And in Portugal?

Portugal records about 1,280 new melanoma cases and 299 deaths a year.¹¹ In summer the IPMA often rates the UV risk in Lisbon as high to very high.¹² Today's index is on ipma.pt.

Why the car matters

Ordinary glass stops most UVB but lets part of the UVA through.^4,5 Side windows are usually tempered glass, which transmits more UVA than other kinds of glass.^5,6

Anyone who drives every day spends hours with an arm and one side of the face turned to the window. In 2012 the New England Journal of Medicine published the photo of a delivery driver who had driven for 28 years. The side of his face turned to the window had visibly older skin.¹³ It is one case, not a statistic — but it shows what years of UVA through glass can do.

How the film reduces exposure

A quality film has UV filters built into the material. Cancer Council Australia, the country's leading cancer organisation, states that clear or tinted films can cut the UV coming through tempered glass by more than 99%.⁹

UV protection does not depend on colour. A clear film can block as much UV as a dark one.⁹
It only works with the window closed.⁹
Some people need it more. The British Association of Dermatologists notes that people sensitive to UVA may need photoprotective film on their car windows.¹⁰
There is a market benchmark. The Skin Cancer Foundation only recommends films that block at least 99% of UVA and UVB.¹⁴

We fit LLumar AU 85 UV SR HPR, from Eastman's UV Shield series: clear, it lets 87% of the light through and blocks more than 99% of UV radiation (wavelength 300–380 nm), according to the maker's data sheet.^P The film is on the IMT's official list of films with recognised homologation (approval D 5683), in the part for films that may also go on the windows in front of the B-pillar.^IMT

On the rear windows we also fit dark LLumar IRX films, which are on the IMT list too (D 5715, D 5716).^IMT They give privacy, but the UV protection does not come from the colour: it comes from the film's filters.⁹ See the films and their homologation.

What the film does not do

It is not a medical treatment and does not replace sunscreen or sunglasses. It works alongside them.
It does not stop visible light. Patches such as melasma are also worsened by visible light; for that, dermatologists recommend tinted sunscreen.¹⁵
It does not protect with the window open.

The law in Portugal

Every film must be homologated and registered with the IMT, and the front side windows have rules of their own. We explain it all in window tinting and the law in Portugal.

Other ways to protect yourself

Sunscreen with UVA protection. In the EU, look for the UVA symbol in a circle.
Sunglasses with a UV filter (UV400).
See a dermatologist if you have new moles or ones that change.

Sources

Checked in October 2026.

1. IARC Monographs, Vol. 100D — Radiation (2012); El Ghissassi F. et al., Lancet Oncology 2009;10:751–2. PMID 19655431.
2. IARC, press release n.º 367 (27.05.2025); Langselius O. et al., International Journal of Cancer 2025;157:1110–9. PMID 40421619.
3. WHO, «Ultraviolet radiation», fact sheet (2022).
4. Tuchinda C. et al., «Photoprotection by window glass, automobile glass, and sunglasses», J Am Acad Dermatol 2006;54:845–54. PMID 16635665.
5. Almutawa F. et al., «Current status of photoprotection by window glass, automobile glass, window films, and sunglasses», Photodermatol Photoimmunol Photomed 2013;29:65–72. PMID 23458389.
6. Hampton P.J. et al., «Implication for photosensitive patients of ultraviolet A exposure in vehicles», Br J Dermatol 2004;151:873–6. PMID 15491429.
7. U.S. Food and Drug Administration, «Ultraviolet (UV) Radiation»; Cancer Research UK, «How does the sun and UV cause cancer?».
8. Halliday G.M. et al., «Ultraviolet A radiation: its role in immunosuppression and carcinogenesis», Semin Cutan Med Surg 2011;30:214–21. PMID 22123419.
9. Cancer Council Australia, «Tinted windows» (2017).
10. British Association of Dermatologists, «Chronic actinic dermatitis», patient leaflet (2021).
11. IARC Global Cancer Observatory, Portugal — GLOBOCAN 2024.
12. IPMA, previsão do índice UV.
13. Gordon J.R., Brieva J.C., «Unilateral dermatoheliosis», N Engl J Med 2012;366:e25. PMID 22512500.
14. Skin Cancer Foundation, Seal of Recommendation.
15. Castanedo-Cazares J.P. et al., Photodermatol Photoimmunol Photomed 2014;30:35–42. PMID 24313385.
P. Eastman Performance Films, «LLumar — Película automóvel, informação técnica: AU 85 UV SR HPR (Clear)», 26-01-2023 (NFRC data, 6 mm single clear glass).
IMT. IMT — Instituto da Mobilidade e dos Transportes, «Listagem de películas com homologação reconhecida», Lista 61 (31-10-2024). imt-ip.pt

For information only. Not a substitute for medical advice.