SPF UVA and UVB Protection: Why it's Important Year-Round

Sun protection is essential every day of the year, not just during the sunny months. UVB rays are strongest during the summer months, but UVA rays are present all-year round, and can penetrate both clouds and windows, exposing your skin even when you're indoors, or the weather is overcast. Wearing broad-spectrum sunscreen with at least SPF 30 daily helps prevent premature signs of aging, including wrinkles, fine lines, and hyperpigmentation, as well as reducing your risk of skin cancer. Understanding the effects of everyday UV exposure is important so you can build a skincare routine that supports your skin health long-term.

What Are UVA and UVB Rays?

The sun gives off two types of ultraviolet (UV) rays that affect your skin: UVA and UVB. Both UVA and UVB rays can cause skin damage and cancer, so protecting yourself from both will keep your skin healthy.

UVA Rays

UVA rays make up about 95% of the UV radiation that reaches the Earth’s surface. They have a longer wavelength, which allows them to penetrate the skin’s outer layer and reach deeper into the dermis.

These UVA rays can cause:

Premature aging (e.g., fine lines, wrinkles, sun spots, sagging skin)
Gradual decline in skin elasticity
Long-term skin damage

UVB Rays

UVB rays have a shorter wavelength, and are the main cause of sunburns because they can directly damage the DNA in your skin cells. When your skin is constantly getting damaged faster than your body can fix it, you’ll get a sunburn, which raises your risk of skin cancer.

UVB strength varies depending on the season, time of day, and your location. However, reduced intensity doesn't mean there isn’t any risk of exposure. Even in winter, UVB rays can still reach your skin, especially at higher elevations or near reflective surfaces like snow.

What Does SPF Measure?

SPF stands for Sun Protection Factor, and it measures how well a sunscreen product will help prevent damage from UV rays, primarily UVB rays. Below are different types of SPF sunscreen.

SPF 30 blocks about 97% of UVB rays. Shop our recommended SPFs 30s:

SPF 40 blocks about 97.5% of UVB rays. Shop our recommended SPFs 40s:

SPF 50 blocks about 98% of UVB rays. Shop our recommended SPFs 50s:

To protect your skin against UVA rays as well, you should wear a broad-spectrum sunscreen to protect against both UVA and UVB rays. Shop all recommended sunscreens.

What Are the Effects of Not Using Sunscreen?

Skipping sunscreen doesn’t usually show skin damage right away. Sun damage builds gradually over time and can affect your skin in several different ways.

Premature Aging

Up to 90% of visible skin aging comes from sun exposure. UVA rays break down collagen and elastin, which causes wrinkles, fine lines, and dull, sagging skin. One of the best ways to help prevent premature aging is wearing SPF every day.

Skin Cancer

Too much UV exposure is a leading factor in skin cancer, including melanoma, the most dangerous form of skin cancer. Both UVA and UVB rays contribute to skin cancer, which is why daily sun protection is so important for long-term skin health.

Hyperpigmentation

Sun exposure increases melanin production in the skin, which is why this often causes dark spots, uneven skin tone, and melasma. Treatments can help improve hyperpigmentation, however, without daily SPF use, it often comes back.

When to Apply Sunscreen in Your Skincare Routine

Sunscreen should be the final step in your morning skincare routine; apply it after your moisturizer and before your makeup. This helps create an even, protective layer on the skin’s surface without being diluted or disrupted by other products. Make sunscreen a part of your morning skincare routine to help protect your skin from daily UV exposure and support long-term skin health. Don’t forget to apply sunscreen to your ears, neck, hands, hairline, and lips. Reapply every two hours when you're outdoors, sweating, or swimming.

FAQs

What type of SPF should I use?

You should wear broad-spectrum SPF 30 or higher everyday. SPF 30 is great for daily use, if you’re indoors, and short periods of time outdoors. SPF 50 is better if you’re outside for extended periods of time, have sensitive skin, or are exposed to higher UV rays.

Is it bad to leave sunscreen on overnight?

Leaving sunscreen on overnight isn’t harmful, but you should wash it off so your skin can properly cleanse, breathe, and repair itself.

How often should you apply sunscreen?

Apply sunscreen every morning as the last step in your skincare routine, and reapply every 2 hours when you’re outdoors or exposed to direct sun. Reapply more often if you’re swimming or sweating.