Sunscreen in Winter?
Q: I donʼt get sun in winter, so why do I need to wear sunscreen?
A: Many people mistakingly think sunscreen is not needed during winter months. This
myth is out-dated just like the belief that tanning with baby oil was good for our health.
Although it is true that the intensity of UVB decreases in winter, UVA ﬂuctuates
minimally and is a major component of the sunʼs longer winter wavelengths. Therefore,
the vast majority of UV exposure throughout the calendar year (and throughout your
entire life) is UVA, which contributes to skin cancer and premature aging. You are
exposed to UVA every time you walk outside to your mailbox, drive your car, or sit next
to a window, even on a cloudy day. UVA penetrates through clouds and also window
glass (think how the word glass has an A in the middle of it).
Q: What kind of sunscreen do I need in winter?
A: One that is “broad spectrum” and protects against UVA. Years ago we believed that
UVB was the only culprit behind aging and cancer; therefore the early generation of
sunscreens protected against UVB only. Now scientiﬁc evidence has proven that UVA
is dangerous and causes cancer as well. This lead to the development of different
chemicals that also block UVA. But you do not have to start memorizing the alphabet
soup of odd chemical names to make sure you are getting appropriate protection. The
Food & Drug Administration (FDA) recently passed new regulations on sunscreen
labeling. Products labelled “broad spectrum” are required to contain chemical or
physical agents that protect you from both UVA and UVB. I usually recommend use of
a daily facial moisturizer with an SPF of 30 or higher to be applied every morning before
you ever leave your house. Physical blocking agents such as zinc and titanium are
better than the chemical blockers (ones that have an SPF number) because they block
every wavelength. However, many people do not like the white pale appearance that the
particles leave on their skin. Luckily, new products now exist that minimize this
undesired complexion change by creating smaller zinc particle sizes, such as EltaMD
sunscreen products. EltaMD products are available for purchase in our ofﬁce.
Q: I heard that vitamin D levels are usually lower in winter. Will wearing sunscreen
affect my vitamin D levels?
A: Luckily, we live in Houston, which is located at 29.7 degrees latitude. Individuals
living South of 35 degrees North latitude (which is everybody in Texas South of
Amarillo), do not ever stop producing vitamin D, even during the winter. We actually still
get a signiﬁcant amount of UVB, the wavelength responsible for vitamin D production,
throughout the year. To address the speciﬁc issue of vitamin D and sunscreen, the
American Academy of Dermatology released a position statement in 2008-2009. (Link:
http://www.aad.org/forms/policies/uploads/ps/ps-vitamin%20d.pdf). To summarize, the
standpoint of dermatologists is that UV exposure is a risk factor for the development of
skin cancer. There is no scientiﬁcally-proven safe threshold level of UV exposure that
allows for maximal vitamin D synthesis without increasing skin cancer risk. Therefore
sunscreen and sun protection (hats, long-sleeve shirts, pants) are recommended for
everyone. If vitamin D deﬁciency is a concern, vitamin D supplements are
recommended. The current US Department of Agriculture (USDA) guidelines suggest a
daily total dose of 1000 IU (International Units) of vitamin D for adults and 400 IU daily
for children. If you are concerned that your vitamin D level is low, a simple blood test
can be done.