The dangers of UVA radiation

UVA rarely gives you the obvious warning of a sunburn, which is exactly what makes it easy to underestimate. Its harm is mostly cumulative and delayed — built up quietly over years of everyday exposure, including time spent indoors near windows or in the car.

1. Photoaging

This is UVA's signature effect. By reaching the dermis, UVA degrades collagen and elastin — the proteins that keep skin firm and springy — and disrupts their repair. Over time that shows up as wrinkles, sagging, a leathery texture, broken capillaries and uneven pigmentation (sun spots). Researchers estimate the large majority of visible skin aging is caused by sun exposure rather than the passage of years, and UVA is the principal culprit.

2. Indirect DNA damage

Where UVB tends to damage DNA directly, UVA acts mostly indirectly: it's absorbed by other molecules in the skin and generates reactive oxygen species (ROS) — unstable, reactive molecules that go on to damage DNA, proteins and cell membranes through oxidative stress. This roundabout route still produces mutations, and it's a key mechanism behind UVA's role in skin cancer.

3. Skin cancer, including melanoma

Ultraviolet radiation as a whole is classified as a known human carcinogen. UVB has long been tied to common non-melanoma skin cancers, but evidence increasingly implicates UVA in melanoma, the most dangerous form, as well as in overall photocarcinogenesis. Because both bands contribute, sun protection has to cover both — the reason dermatologists stress broad-spectrum products, not just a high SPF (which mainly reflects UVB protection).

4. Immune suppression

UVA (and UV more broadly) can locally suppress the skin's immune response. That's thought to reduce the body's ability to detect and clear newly mutated or pre-cancerous cells — another pathway by which chronic exposure raises long-term risk.

5. Eyes

The eyes are vulnerable too. Cumulative UVA exposure is associated with cataracts and may contribute to other eye conditions. UV-blocking sunglasses — ones rated to block UVA and UVB, ideally wrap-around — meaningfully reduce the dose reaching the eye.

6. Photosensitivity and medication reactions

UVA drives many photosensitivity reactions: rashes or exaggerated "sunburn-like" responses triggered by certain medications (some antibiotics, diuretics and others), cosmetics, or conditions like polymorphous light eruption. Because UVA passes through glass, sensitive individuals can react even indoors.

How to reduce UVA exposure

• Use broad-spectrum sunscreen. Look for "broad spectrum" and UVA indicators — the circled UVA logo or a high PA+++/PA++++ rating — not just a high SPF number.
• Don't trust glass. Windows block UVB but not most UVA; UV-protective film helps for cars and homes if you spend long periods by a window.
• Cover up. Tightly woven clothing, wide-brimmed hats and UV-rated fabrics (UPF) are reliable because they don't wear off.
• Protect your eyes. Sunglasses rated for UVA and UVB.
• Remember it's there on cloudy days and outside summer — UVA is comparatively steady year-round.
• Skip tanning beds. Many emit high, concentrated UVA.