Not Using SPF in Autumn and Winter? Why Sun Protection Is Not Seasonal

Ultraviolet radiation is divided into two main categories that are relevant to the skin: UVA and UVB.

UVB radiation is primarily responsible for sunburn (skin redness after prolonged sun exposure) and plays an important role in skin carcinogenesis. Its intensity varies significantly by season, being higher in summer and lower in winter.

UVA radiation penetrates deeper into the skin and contributes to the breakdown of collagen and elastin fibres, photoaging, the development of wrinkles, and pigmentation disorders. Unlike UVB, UVA intensity varies less throughout the year.

Moreover, UVA radiation can pass through standard window glass, which means exposure may continue even when we spend a great deal of time near a window.

Therefore, although the risk of sunburn is lower in winter, exposure to ultraviolet radiation does not disappear completely.

A useful indicator for deciding when we need sun protection is the UV Index (UVI). It estimates the intensity of ultraviolet radiation and its potential to cause harmful effects on the skin.

The World Health Organization’s recommendations are as follows:

UVI 0–2: the risk from exposure is low, and under ordinary conditions, no additional sun protection measures are necessary for most people.

UVI 3–7: sun protection is recommended, particularly around midday.

UVI 8 or higher: additional protection is necessary, including avoiding exposure during periods of intense radiation.

In Romania, the UV Index decreases considerably during the winter months, so applying SPF every day is not essential in every situation.

However, there are several important exceptions:

1. People who spend a great deal of time outdoors. 2. People who participate in winter sports or go to the mountains, where altitude and the reflection of radiation from snow increase exposure. 3. People with melasma, hyperpigmentation, or other conditions aggravated by light. 4. Patients undergoing dermatological treatments that require photoprotection, depending on the substance used and the medical indication.

It is important to check the local UV Index rather than relying exclusively on the outdoor temperature or the appearance of the sky.

When photoprotection is necessary, the recommendation is to choose a product with:

• SPF 30–50+: provides protection against UVB radiation. • UVA protection: check for the UVA symbol inside a circle on the packaging, which indicates compliance with the European standard for UVA protection. • Broad-spectrum protection: the product should protect against both UVA and UVB radiation.

To obtain the level of protection stated on the packaging, it is important to apply a sufficient amount of product—approximately 2 mg/cm² of skin. Or, more simply, use the “two-finger rule”: apply a line of SPF along the entire length of both the index and middle fingers. This is the recommended amount for use on the face.

During prolonged outdoor exposure, sunscreen should be reapplied approximately every two hours and after heavy sweating, swimming, or wiping the skin.

In addition, photoprotection is not limited to applying sunscreen. Hats, sunglasses, suitable clothing, and avoiding exposure during periods when the UV Index is high provide additional skin protection.

One important point: if you spend most of the day indoors, have no meaningful outdoor exposure, and the UV Index is low, applying SPF should not be regarded as a universal requirement.