UVA rays represent the longest portion of the ultraviolet spectrum emitted by the sun, with a wavelength ranging from 315 to 400 nanometers.
They account for about 95% of the UV radiation that reaches the Earth’s surface and penetrate deeper into the skin than UVB rays, reaching all the way to the dermis.
Unlike UVB rays, which cause visible sunburn, UVA rays act insidiously: their effects are not immediately noticeable but accumulate over the years.
They play a major role in skin photoaging and certain sun-induced allergies, and they also contribute to the long-term risk of skin cancer.
The distinction between UVA and UVB rays is based on their wavelength and their effect on the skin.
UVA rays (315–400 nm) have a longer wavelength, penetrate deeply into the dermis, and are primarily responsible for photoaging and certain sun allergies.
UVB rays (280–315 nm) have a shorter wavelength, stop at the epidermis, and are primarily responsible for red, painful sunburns.
UVA levels remain roughly the same throughout the year and throughout the day, while UVB levels vary significantly depending on the time of day, season, and latitude.
Protection against UVA rays relies on several cumulative measures:
Reapply every 2 hours and after swimming, sweating, or drying off with a towel.
Yes, UVA rays pass through standard glass, unlike UVB rays, which are largely filtered out.
Whether in a car, in an office near a window, or in a sunny room, exposure to UVA rays is still possible and silently contributes to skin photoaging.
Studies have shown asymmetry in skin aging among drivers (more pronounced on the left side in France, which is exposed to the driver’s side window).
For more comprehensive protection, UV-blocking films or treated glass can be installed on windows; daily sunscreen on the face and hands is still recommended year-round.
Repeated exposure to UVA rays has several cumulative effects:
Regular dermatological screenings are recommended for people with fair skin, a personal or family history of skin cancer, or significant sun exposure.
UVA rays are the primary cause of skin photoaging.
Because they penetrate deeply, they damage the collagen and elastin fibers in the dermis, which visually results in a loss of firmness and the appearance of premature wrinkles.
They also contribute to the development of pigment spots (solar lentigines) on the most exposed areas: the face, the backs of the hands, the décolleté, and the ears.
Prevention through daily broad-spectrum sun protection is now considered one of the most effective anti-aging measures.
Several criteria indicate effective protection against UVA rays:
Yes, UVA rays contribute to the risk of skin cancer, even though their role is more indirect than that of UVB rays.
They cause cellular damage (oxidative stress, DNA damage) that accumulates over the years.
The types of skin cancer involved include melanoma, basal cell carcinoma, and squamous cell carcinoma.
Any unprotected exposure, even without visible sunburn, contributes to this cumulative risk. An annual dermatological screening is recommended for those at risk.
The circled UVA logo is a European label established by the European Commission’s 2006 recommendation.
It guarantees that the product’s UVA protection is at least one-third of its UVB protection (SPF). In other words, an SPF 30 provides a minimum UVA protection equivalent to SPF 10.
This is an essential criterion for choosing a sunscreen that truly offers broad-spectrum protection, rather than simply a high SPF.
Always choose products that display this circled UVA logo on the packaging in addition to the listed SPF.
UVA rays are strongly implicated in several forms ofsun allergy:
People prone to these reactions should use SPF 50+ sunscreens with enhanced UVA protection and strictly limit their sun exposure. Consult a dermatologist if you experience recurring rashes.
Tanning beds primarily emit UVA rays, which can be up to 10 to 15 times more intense than the midday sun at the equator, depending on the model.
The International Agency for Research on Cancer (IARC, WHO) classifies UV radiation from tanning beds as **definitely carcinogenic to humans (Group 1)**, on par with tobacco and asbestos.
French health authorities (ANSM, INCa) strongly advise against their use, particularly before the age of 30, due to the documented increase in the risk of melanoma.
For a safe tan, opt for DHA-based self-tanning products that do not involve UV exposure.
UVA rays cause immediate tanning (within a few hours) by oxidizing the melanin already present in the skin.
This tan is superficial, temporary, and provides only extremely limited skin protection (equivalent to an SPF of 2 to 4 at most).
A lasting tan, which develops later (24–72 hours), results primarily from the action of UVB rays, which stimulate the production of new melanin.
In any case, tanning remains a defensive response by the skin to UV exposure: it does not replace the need for sunscreen.
Children’s skin is thinner, more permeable, and their defense system is still immature, making them vulnerable to both UVA and UVB rays.
Repeated exposure during childhood is a major risk factor for skin cancer in adulthood; prevention starting at a very young age is essential.
Infants under 6 months: no direct sun exposure; sunscreens are not always suitable for this age group—consult a pediatrician first.
For older children, combine a pediatric broad-spectrum SPF 50 sunscreen with UV-protective clothing, a hat, sunglasses, and avoiding the sun during peak hours.
Certain medications and cosmetics make the skin particularly sensitive to UVA rays (a phenomenon known as photosensitization).
Indicative list: certain antibiotics (cyclines, fluoroquinolones), antifungals, antidepressants, NSAIDs, diuretics, certain medical retinoids (tretinoin, isotretinoin), Cordarone, and others.
As for cosmetics: retinol, AHAs (glycolic acid), BHAs (salicylic acid), vitamin C, and citrus essential oils (bergamot, lemon) can also cause photosensitivity.
Always check the package insert for your medications and the ingredients in your cosmetics, and ask your pharmacist or doctor for advice if you have any doubts before sun exposure.
Incorporating UVA protection into your daily routine is one of the most effective anti-aging practices documented.
Apply a broad-spectrum sunscreen every morning as the final step in your routine, after cleansing, applying serum, and moisturizing.
Reapply every 2 hours when exposed to the sun, and always after swimming, sweating, or toweling off.
Your face, hands, and décolletage deserve protection year-round, even on cloudy days or in winter, because UVA rays are present almost all the time, regardless of the season.
