We all recognize the importance of daily sunscreen use, but how much do we really understand about how it works? To shed light on this essential skincare product, we turned to Medical Grade Skincare Expert, Lindsey, for expert insights into the most common sunscreen queries.
How Sunscreen Shields Your Skin
SPF (sun protection factor) can be classified into two types: mineral (or physical) and chemical. Mineral sunscreens, containing zinc oxide and titanium dioxide, act as a physical barrier, deflecting the sun’s rays. Chemical sunscreens, with ingredients like avobenzone and octinoxate, absorb UV rays before they can harm your skin. Both types are effective in safeguarding your skin.
Decoding Sun Protection Factor (SPF)
SPF indicates a sunscreen's ability to block UVB rays, the primary cause of sunburn. Lindsey explains that SPF 15 blocks about 93% of UVB rays, SPF 30 about 97%, and SPF 50 around 98%. SPF testing is rigorously conducted in line with the Health Canada's and the FDA's (USA) guidelines.
SPF doesn’t measure protection against UVA rays, linked to premature skin aging. Lindsey recommends opting for broad-spectrum sunscreens that shield from both UVA and UVB rays for comprehensive protection.
Does Sunscreen Prevent Tanning?
Even with sunscreen, tanning is possible, as no sunscreen blocks 100% of UV rays. However, any skin darkening indicates not just UV damage and increasing the risk of skin cancer, but the formation of tan (even a light one) is simply DNA damage. Thus, the safest tan is a fake one.
Why SPF 50+ Is the Limit
While SPF 15 and 30 differ significantly in protection, the gap narrows beyond SPF 30. Sunscreens over SPF 50 offer minimal additional coverage. “High SPF values can give a false sense of security,” Lindsey cautions, emphasizing the importance of regular reapplication.
How Often to Reapply Sunscreen
A general guideline is to reapply sunscreen every two hours. Health Canada regulations also recommend reapplication every 40 to 80 minutes during swimming or sweating.
Sunscreen Expiry and Storage
Using sunscreen before its expiration date for optimal protection. Proper storage is crucial, as heat and direct sunlight can degrade sunscreen ingredients.
Lotion vs. Spray Sunscreen
Both lotion and spray sunscreens are effective if applied correctly. Lindsey prefers lotions for more reliable protection, noting that sprays can be less effective, especially in windy conditions.