Good skin care is important for prevention of premature aging. Protection from the ultraviolet radiation of the sun is fundamental to maintaining healthy appearing skin. In addition to causing skin cancer, cummulative ultraviolet radiation contributes to the appearance of aged skin, wrinkles, and uneven pigmentation.
UV radiation is made up of 96.5% UVA radiation and 3.5% UVB on an average summer day. UVA is believed to be a cause of melanoma cancer and can penetrate deep within the skin to cause wrinkles. UVB is linked to squamous cell carcinoma. Most sunscreens protect against UVB but you should check to see if they also protect against UVA. Suncreens are rated according to SPF (sun protection factor) for UVB radiation only. This is a multiple of the amount of sun exposure time one can experience to recieve the same degree of UVB absorption without sunscreen. For example, someone wearing SPF 30 can be in the sun 30 times longer to receive the same UVB absorption without the sunscreen.
Sunscreens come in two types: physical blockers and chemical blockers. Physical blockers known as barrier sunscreens, are not absorbed by the skin and reflect the UV radiation. Titanium dioxide, zinc oxide and magnesium oxide are some common ones. They rarely cause allergic reactions. Chemical blockers are absorbed and therefore have a risk of allergic reaction. They are usually combined with barrier suncreens for periods of increased sun exposure. Helioplex which is a stable form of avobenzone, or Mexoryl are currently considered among the the best.
An SPF of 30 or higher is recommended and should be reapplied every couple hours or as needed based on activity. Avoiding direct sun during the peak hours of 10am -2pm is also advised.