UVA
UVA — a type of ultraviolet radiation with longer wavelengths that penetrates deeper into the skin and is present consistently throughout daylight hours and across seasons. It is strongly associated with skin aging and long-term damage, and it can pass through clouds and window glass.
Key points
- UVA rays have longer wavelengths than UVB and reach into the deeper dermal layers of the skin.
- UVA is a major contributor to photoaging, breaking down collagen and elastin and contributing to wrinkles and pigmentation.
- Unlike UVB, UVA intensity stays relatively constant throughout the day and year and can penetrate clouds and glass.
- Broad-spectrum sunscreens and filters such as zinc oxide and avobenzone are used to help protect against UVA.
Frequently asked
Can UVA rays reach me indoors or in a car?
Yes, UVA can pass through standard window glass, so exposure can occur near windows or while driving even without direct sun.
Is UVA or UVB responsible for aging?
UVA is the primary driver of photoaging because it penetrates deeply and degrades collagen, though both UVA and UVB contribute to overall skin damage.
Related topics
This is a foundational entry in the SYNC Skin Encyclopedia and is expanded over time. Educational information only — not medical advice.
