Sun protection is for everyone, but if you’re struggling to control certain skin conditions it’s particularly important to get the right kind of protection. The primary stressor for inflammation-based conditions like photoaging, rosacea and hyperpigmentation is, you guessed it, sun exposure.
Here are some common sun traps and tips to help you avoid them.
Photoaging and UV exposure
UVB—burning rays which penetrate to the epidermis cause redness and itching, damage DNA and are linked to squamous and basal cell carcinomas. At their peak between 10am to 4pm, UVB rays reflect off shiny surfaces, making snow, sand and water excellent sunburn accelerators.
UVA—aging rays penetrate to the dermis and cause wrinkles by cross-linking collagen and elastin, and hyperpigmentation because they turn melanin darker. Present from sunup to sundown, they penetrate clouds and glass.
Avobenzone protects against longer wavelength UVA rays, up to 400 nm, but it degrades quickly in the presence of UV. It is usually stabilized with octocrylene, however octocrylene is a new, emerging photoallergen that can create photoallergic contact dermatitis in adults. Allergic adults are advised to stay away from sunscreen products containing octocrylene, benzophenone-3 and fragrances. Octinoxate is sometimes added to the mix because it provides good protection in the UVB range, but it also degrades avobenzone and limits stabilization of avobenzone by octocrylene (a good explanation of why can be found here). You’ll want to avoid octocrylene anyway because an allergy may develop. The safest—and easiest—path is to simply avoid sunscreen with the following chemicals: avobenzone, octocrylene, octinoxate, benzophenone-3 and fragrances.
Use instead zinc oxide—it protects up to and past the 400 nm range, and is very stable.
Let’s revisit the reapplication rule. The standard reapplication rule is every two hours. A little-known but true factoid is that the rule exists not because you sweat or wash it off after a certain amount of time, but because chemical sunscreens have a nasty habit of degrading in sunlight (because they work by absorbing UV energy) rather quickly. They then start to generate their own free radicals. If you are using a chemical sunscreen be sure to follow the two-hour rule vigilantly, since you are reapplying throughout the day to protect yourself from the sun and from degraded sunscreen chemicals.
Reapply zinc oxide sunscreen SPF 30 after a swim or if you sweated it off, but a morning application will continue to protect all day under normal, everyday conditions. If you are skiing, at altitude, at the beach, etc., reapply zinc oxide every two to three hours.
Rosacea and UV Exposure
Rosacea involves a complex interaction of different factors and pathways leading to a chronic inflammatory and vascular response. A major instigating factor is UVB/ UVA exposure.
UVB rays penetrate to the epidermis and increase secretion of two factors, vascular endothelial growth factor (VEGF) and fibroblast growth factor 2 (FGF2). These increase vascularization of the skin and cause swelling.
UVB triggers activation of vitamin D3, which directly induces the expression of cathelicidin. Cathelicidin is an antimicrobial peptide that, when processed by rosacea-type skins results in vasoactive and pro-inflammatory peptides and peptide fragments.
UVA and UVB—UV irradiation also produces reactive oxygen species (ROS), which cause vascular and dermal matrix damage by stimulating enzymes, which break down collagen in the dermal matrix. A damaged dermal matrix may permit leakage and accumulation of inflammatory mediators and prolonged retention of inflammatory cells.
Many people with rosacea simply do not tolerate sun very well at all and are advised to limit their sun exposure. However because we all like at least some sun, the suggestions below will help boost your tolerance.
Hyperpigmentation and UV Exposure
UVB stimulates melanin biosynthesis.
UVA turns melanin darker.
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