SCHAUMBURG, Ill., May 1 /PRNewswire/ -- In the car, at work or walking
to and from a store, you can't escape the sun's ultraviolet (UV) rays.
However, new research about the transmission of UV light through window and
automobile glass and through sunglasses, has led to developments that can
help protect people from the sun.
"People should realize that even during everyday activities they are
receiving incidental sun exposure which harms the skin as it accumulates
and can result in premature aging, wrinkles and even skin cancer," said
dermatologist Henry W. Lim, M.D., chairman of the department of
dermatology, Henry Ford Hospital in Detroit, Mich., and co-author of the
Journal of the American Academy of Dermatology article entitled,
"Photoprotection by window glass, automobile glass and sunglasses."
"Dermatologists and manufacturers of glass products and sunglasses are
continually working to find better ways to decrease the amount of UV
radiation being filtered through these items to the skin and eyes. These
advances are helping to reduce the amount of UV exposure that a person
receives on a daily basis."
UV radiation from the sun comes in two forms: ultraviolet A (UVA) and
ultraviolet B (UVB). UVB has long been associated with sunburn while UVA
has been recognized as a deeper penetrating radiation that contributes to
premature aging and wrinkle formation. Both of these types of rays have
been linked to the development of skin cancer. More than 1 million new
cases of skin cancer are diagnosed each year.
Window Glass and Photoprotection
Window glass filters out UVB rays, but UVA rays are still transmitted
to the skin through the panes. The type of glass and the type of coating on
the glass can affect the percentage of UV radiation that is transmitted to
the body. Most residential buildings have one of three types of glass:
clear, tinted or reflective. Of these three, reflective glass, the kind
that eliminates the ability to see the interior of a building from the
outside during the day, minimizes unwanted solar heat gain and reduces UV
transmission to less than 25 percent. This means nearly one-quarter of the
UV exposure, exclusively the longer wavelength UVA, is reaching the inside
though, remarked Dr. Lim.
"Most Americans spend 80 percent of their day indoors at work or
school," stated Dr. Lim. "With the new trend in architecture toward more
and larger windows in buildings, protection from UV exposure when indoors
has become an important issue for not only the cost-effectiveness of
cooling a building, but also for the health and safety of the employees who
work within it."
Recent developments in window glass include low-emissivity (low-E)
glass which has a special surface coating between layers of antireflective
glass. This type of glass reflects up to 70 percent of solar heat and
reduces UV transmission through the panes to 20 percent.
To protect the skin from the damaging rays of the sun when working
indoors, it is important to: arrange workspace so that the body is not in
direct sunlight; and use blinds or shades on the windows during peak sun
Automobile Glass and Photoprotection
In studies of UV exposure in cars, it was shown that the parts of the
driver's and passenger's bodies closest to the window received the greatest
UV exposure. Side and rear windows are usually made from non-laminated
glass, allowing a significant amount of UVA to pass through to the
passengers in the car. Most windshields are made from laminated glass, the
type of glass designed to prevent fragments from shattering onto the
occupants during an accident and which can filter both UVB and a large
portion of the UVA rays.
Tinting automobile glass is an option that allows 3.8 times less UVA
light to be transmitted to the interior of the car as compared to untinted
window glass. In a 2004 study of UV transmission and color tint, grey
tinted laminated glass provided the highest UV protection with only 0.9
percent of UVA light transmitted versus 62.8 percent transmitted through
non-laminated clear glass. People who are considering tinting their windows
should take their car to a professional auto detailing shop, in order to
ensure that the tinting meets the federally mandated 70 percent of minimum
visible light transmittance through the windshield.
"Obviously UVA exposure in a car is influenced by non-glass-related
factors such as position of the individual in the vehicle, direction of
travel with respect to the sun, and time of day," stated Dr. Lim. "However,
the more time a person spends in a car, especially at the same time of day
such as during a regular commute, can greatly affect the amount of UV
exposure their skin receives."
To reduce sun exposure while driving, wear protective clothing, such as
a long-sleeved shirt and pants, especially when the body is in the sun;
apply sunscreen generously to any exposed skin before driving, especially
the hands, forearms and face; and wear protective sunglasses to reduce
glare and protect the eyes from UV exposure.
Sunglasses and Photoprotection
UV radiation is potentially hazardous to the structure of the eyes,
particularly the cornea, lens and retina, which is why the U.S. developed a
"sunglass standard," with the latest version published in 2001. Sunglasses
are classified into three categories: cosmetic sunglasses providing minimal
UV protection; general purpose sunglasses designed to reduce glare in
bright light or when driving; and special purpose sunglasses for activities
such as skiing or going to the beach.
"The ideal sunglasses should substantially reduce UV exposure to the
cornea and the lens, including any UV coming from lateral directions, and
should wrap around the eyes, thereby maximizing eye and eyelid protection,"
said Dr. Lim. "For even better protection, wear a broad-brimmed hat which
can help reduce the level of UV radiation reaching the eyes and the
In addition, Dr. Lim recommended the following tips when purchasing
sunglasses to maximize UV protection:
-- Look for neutral gray and amber brown lenses that give true color
rendition, particularly to red and green stoplights.
-- Seek glasses with a large frame and lenses that cover the entire eye
and wrap around the side of the eye.
-- Look for the "100% UV Protection" sticker to ensure that the
sunglasses meet standards for safe levels of UV protection.
Expensive sunglasses do not necessarily provide better UV protection,
according to Dr. Lim. Darkly tinted sunglasses can make pupils dilate and
increase lid opening, thereby resulting in increased UV exposure to the
lens of the eye.
In addition to wearing sun protective clothing, including sunglasses,
you should follow these sun protection tips and Be Sun Smart(SM):
-- Generously apply sunscreen to all exposed skin using a Sun Protection
Factor (SPF) of at least 15 that provides broad-spectrum protection
from both ultraviolet A (UVA) and ultraviolet B (UVB) rays. Re-apply
every two hours, even on cloudy days, and after swimming or sweating.
-- Seek shade when appropriate, remembering that the sun's rays are
strongest between 10 a.m. and 4 p.m.
-- Use extra caution near water, snow and sand as they reflect the
damaging rays of the sun which can increase your chance of sunburn.
-- Protect children from sun exposure by applying sunscreen.
-- Get vitamin D safely through a healthy diet that includes vitamin
supplements. Don't seek the sun.
-- Avoid tanning beds. Ultraviolet radiation from the sun and tanning
beds causes skin cancer and wrinkling. If you want to look like
you've been in the sun, consider using a sunless self-tanning product,
but continue to use sunscreen with it.
-- Check your birthday suit on your birthday. If you notice anything
changing, growing, or bleeding on your skin, see a dermatologist.
Skin cancer is very treatable when caught early.
May 1 is Melanoma Monday and the launch of Melanoma/Skin Cancer
Detection and Prevention Month(R). For more information about skin cancer,
please visit http://www.skincarephysicians.com and click on
The American Academy of Dermatology (Academy), founded in 1938, is the
largest, most influential, and most representative of all dermatologic
associations. With a membership of more than 15,000 physicians worldwide,
the Academy is committed to: advancing the diagnosis and medical, surgical
and cosmetic treatment of the skin, hair and nails; advocating high
standards in clinical practice, education, and research in dermatology; and
supporting and enhancing patient care for a lifetime of healthier skin,
hair and nails. For more information, contact the Academy at 1-888-462-DERM
(3376) or http://www.aad.org .
SOURCE American Academy of Dermatology