In the summer months the urge to spend time outdoors is
irresistible. We use sunscreen to avoid getting burned,
but the way it works is a mystery. Clinically speaking, a
sunburn is a skin inflammation, but it is the skin’s
absorption of the sun’s ultraviolet rays that changes our
DNA structure and can eventually cause damage, including
skin cancer and premature aging.

Sunscreens work either by absorbing ultraviolet light
before it reaches the skin or by reflecting light away from
it. SPF, the familiar measurement of most sunscreens,
refers to the level of protection against UVB rays.
Sunscreens with SPF 15 or 30 block 93% and 96.7% of
UVB light, respectively. Dermatologists recommend
blocks with a high SPF and ingredients such as
Parsol 1789, titanium dioxide or zinc oxide, which offer
protection against a broader spectrum of light, including
dangerous UVA and UVB rays.

Sunscreen should be applied 30 minutes before sun
exposure and reapplied every two hours. Factor in
perspiration, temperature, humidity and time spent in the
water and even more frequent reapplication is necessary–
even if the product is “waterproof.” The Journal of
American Academy of Dermatology reported recently that
most people don’t apply enough sunscreen to reach the
level of SPF listed on the label: the best bet is to opt for
SPF 30 to ensure that you are getting effective coverage.
To further maximize your protection, avoid direct sunlight
during 10am and 4pm and wear a hat with a wide brim or
clothes of woven fabrics scientifically designed to
minimize UV absorption.

But sunscreen does not eliminate the risk of skin cancer,
caused by cumulative sun exposure.