contact information
- NYC Dermatologist Center
- 30 East 60th Street
- Suite 805
- New York, NY 10022
- Tel: 212-644-9494
- Map
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This service should not be used in place of a visit, call, consultation with or the advice of your healthcare provider.
Communicate promptly with your provider with any health related questions or concerns.
- Highlights
- Skin Cancer
- Sunscreens
Sun Protection
Sunlight is responsible for many skin problems, including sunburn, age spots, scaly growths (actinic keratoses), wrinkles,
melasma, freckles, and allergic rashes.
Most importantly, it is the major cause of skin cancer, including melanoma. It is important for everyone to be aware of its damaging effects and take measures to avoid overexposure.
Although many people enjoy the appearance of tanned skin and think it looks "healthy," tanned skin is damaged skin. The ultraviolet radiation in sunlight penetrates the deepest layers of the skin where it harms the cells. The body responds by making more pigment (melanin) to try to protect itself, but the damage has already happened and may be permanent. The more exposure you have to the sun, the more likely you are to develop skin problems later in life.
Ultraviolet Radiation
The damaging part of sunlight is called ultraviolet radiation, or UV rays. It is categorized into three types:
- UVC rays (wavelengths = 200 nm to 290 nm) are the shortest and most powerful of the UV rays. UVC is the most likely to cause cancer if it reaches skin. Fortunately, most of it is absorbed by the ozone layer in our atmosphere. However, there is concern that a thinning of the ozone layer may be causing more UVC to reach the earth's surface.
- UVB rays (wavelengths = 290 nm to 320 nm) are less damaging than UVC, but more of it penetrates to the earth's surface. It is the most common cause of sunburn and skin cancer. UVB is particularly strong at the equator, at high elevations, and during the summer.
- UVA rays (wavelengths = 320 nm to 400 nm) are the least powerful of the UV rays, but they are present all year and can penetrate windows and clouds.
Sun Protection
The first and more effective way to avoid sun damage is to stay out of tthe sun as much as possible.
If you cannot avoid being exposed to sunlight, there are five basic defenses that you should keep in mind when you go outdoors:
- Avoid peak hours of sunlight
- Sunscreen
- Clothing
- Sunglasses
- Shade
Avoid Peak Hours of Sunlight (UV Index)
In general, UV rays are the greatest between 10 a.m. and 4 p.m. It is best to avoid the outdoors during these hours without protection, particularly during summer, in tropical regions, or at altitude. During this time, you should pay close attention to the appropriate use of sunscreen, clothing, sunglasses, and shade.
You can obtain an accurate measure of the amount of UV rays in your area by looking up the Ultraviolet (UV) Index. The UV Index is like a weather forecast. It provides a report on the amount of damaging UV rays that are expected to affect a region on a particular day. The UV Index changes day to day according to time of year, cloud cover, atmospheric ozone, and other factors.
The following table is a breakdown of the UV Index. A high UV Index number means that you are at greater risk of being exposed to ultraviolet radiation. You should take special care to avoid outdoor exposure to sunlight when the UV Index is moderate or greater.
- 0 to 2 = Minimal
- 3 to 4 = Low
- 5 to 6 = Moderate
- 7 to 9 = High
- 10 or more = Very high
The UV Index can be found on our Website or in local papers, usually in the weather section.
Sunscreen
There are several factors to consider when selecting the right sunscreen. (See the Sunscreens handout for more information.)
Sun protection actor (SPF) - Sunscreens are rated by the amount of protection they provide from UVB, measured as the "sun protection factor" or SPF. Sunscreens with higher SPF provide greater protection from the sun. It is best to use sunscreens that offer a minimum SPF of 15.
Broad-spectrum sunscreens - It is best to use a sunscreen that can protect
you from both UVA and UVB rays. These are called "broad-spectrum" sunscreens.
Most of the original sunscreens
blocked only UVB, but increased awareness of the damage caused by UVA has lead to the development of ingredients that protect
against UVA too. Broad-spectrum sunscreens combine ingredients to provide a product with greater protection.
Common sunscreen ingredients that provide protection from UVB rays:
- Cinnamates
- Octocrylene
- PABA (para-aminobenzoic acid)
- Padimate O and Padimate A (Octyl Dimethyl PABA)
- Salicylates
Common sunscreen ingredients that provide protection from UVA rays:
- Avobenzone (Parsol 1789)
- Benzophenones (oxybenzone, dioxybenzone, sulisobenzone)
Sunblocks - "Physical" sunscreen ingredients lie on top of the skin and work by reflecting or scattering UV radiation. They are particularly useful for people who are sensitive to the ingredients found in other sunscreens. Sunblocks often contain one or more of these ingredients:
- Zinc oxide
- Titanium dioxide
- Iron oxide
Although past formulations were unsightly (often leaving a white film on the skin), newer "microfine" formulations are invisible after being applied. Microfine titanium dioxide is effective at protecting from both UVA and UVB rays.
Water resistance - Sunscreens are classified as "water-resistant" if they maintain their protection after two 20-minute immersions in water. They are classified as "waterproof" if they maintain their protection after four 20-minute immersions. You should seek a water-resistant or waterproof sunscreen if you will be participating in water sports, such as swimming or water skiing, or will be actively sweating.
However, independent testing has shown many products do not perform well in the real world. So it remains a good idea to apply sunscreen every time you leave the water, or frequently if you are actively sweating.
Using a Sunscreen
Sunscreen should be applied evenly and liberally on all sun-exposed skin within 30 minutes before going outside to give sunscreen time to take effect. (Sunblocks are effective immediately after being applied.) Sunscreens should be reapplied every two hours or following swimming or sweating. Apply sunscreen generously and reapply frequently at least every two hours.
The chemicals may lose effectiveness over time, so it is important to throw away sunscreen that is past its expiration date
or is over two years old.
No sunscreen is 100% effective; take additional measures to avoid the damaging effects
of the sun's rays.
Clothing
Clothing can provide excellent protection from the sun. However, not all clothing is protective. A thin, wet, white t-shirt will provide almost no protection from UV rays. When selecting clothes for sun protection, consider the following:
- Cover your head, shoulders, arms, legs, and feet.
- Use a hat that is broad-brimmed (brim should be at least four inches wide).
- Wear fabrics that are thicker or with a tight weave; these allow less sunlight to penetrate the skin.
- Wear darker-colored clothes that absorb more UV rays.
- Wear clothing made from nylon or Dacron because it is more protective than cotton.
- Avoid remaining in wet clothes because wet fabric may allow more UV rays to penetrate the skin.
- Wash clothing with chemical absorbers to increase their protectiveness.
- Some clothing comes with a UPF rating that stands for "Ultraviolet Protection Factor." This measures the ability of the fabric to block UV radiation from penetrating to the skin. A fabric with a UPF 15 allows only 1/15th (6.66%) of the UV radiation to penetrate your skin as compared to uncovered skin.
Garments fall into 3 categories:
- Good protection: UPF = 15 to 24
- Very good protection: UPF = 25 to 39
- Excellent protection: UPF = 40 to 50+
Choose clothing with a UPF rating of at least 15. Keep in mind that the UPF of a garment will decrease over time as the fabric wears.
Sunglasses
Overexposure to sunlight can cause cataracts and macular degeneration, a major cause of blindness. Sunglasses can provide protection. However, not all sunglasses are of value. A darker lens itself does not guarantee protection. Look at the label to ensure that the glasses provide UV protection. Sunglasses should be large enough to shield your eyes from many angles. Look for sunglasses that are described as blocking 99% or 100% of UVA and UVB. The glasses may also be described as providing UV absorption up to 400 nm.
Shade
If possible, remain in the shade when outdoors. Keep in mind that shade does not provide full protection from the sun because UV rays can bounce off reflective surfaces, such as sand, snow, water, concrete, or even porch decks. In addition, some fabrics used as shade devices, such as parasols or umbrellas, may not provide sufficient protection. If you seek shade under a cloth, look for a fabric that is thick, tightly woven, and dark-colored.
Clear window glass provides protection from UVC and UVB, but not UVA rays. If you are frequently exposed to sunlight while driving, the plastic interleaf of your windshield (which prevents it from shattering) can help block the light, but side windows have no such protection. Non-drivers can make use of additional window shade devices. Drivers in some states may be able to use darkly-tinted glass in the side windows, but this is illegal in some states.
Summary
- Avoid the sun when its UV rays are strongest, between 10 a.m. and 4 p.m.
- Use a broad-spectrum sunscreen with SPF 15 or greater. Apply it 30 minutes prior to being exposed to the sun and reapply every two hours. Consider using a water-resistant sunscreen if you will be active (sweating) or in the water.
- Use a sunblock on your lips.
- Wear a broad-brimmed hat when outdoors.
- Wear sunglasses.
- Wear tightly woven, dark clothing to cover your arms, legs, and feet.
- Stay in the shade when possible.
- Avoid reflective surfaces, such as water or snow.
- Avoid sunbathing.
- Don't be fooled by cloudy days since damaging rays can penetrate clouds.
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This information is for general educational uses only. It may not apply to you and your specific medical needs. This information should not be used in place of a visit, call, consultation with or the advice of your physician or health care professional. Communicate promptly with your physician or other health care professional with any health-related questions or concerns.
Be sure to follow specific instructions given to you by your physician or health care professional.
Additional Resources
- Overview
- Conditions
- Prevention
- En Espanol
A blemish begins approximately 2–3 weeks before it appears on your skin's surface. It starts in your sebaceous hair
follicles — the tiny holes commonly called pores. Deep within each follicle, your sebaceous glands are working to produce
sebum, the oil that keeps your skin moist and pliable. As your skin renews itself, the old cells die, mix with your skin's
natural oils, and are sloughed off. Under normal circumstances, these cells are shed gradually, making room for fresh new
skin. But sloughing is different for everyone. Some people shed cells evenly; some don't.
Uneven shedding causes dead cells to become sticky, clumping together to form a plug — much like a cork in a bottle.
This plug, or comedo, traps oil and bacteria inside the follicle. A plugged follicle
The plug traps oil and bacteria within the follicle, which begins to swell as your skin continues its normal oil production.
Your body then attacks the bacteria with a busy swarm of white blood cells. The whole process takes 2–3 weeks, culminating
in a pimple. 
Why me? There is no one simple "cause" of acne — the condition is influenced
by many factors, many which are out of your control. The regularity with which you shed skin cells can change throughout your
life. The rate at which you produce sebum is affected by your hormone balance, which is often in flux — especially for
women. Research has also shown that genetics play a big part in the development and persistence of acne, so your family history
is a valuable prediction tool as well when considering the various causes of acne. One of the best weapons in the fight against
acne, however, is knowledge; if you know what causes acne, it's easier to formulate a good plan
of attack. There are five primary culprits contributing to this process. Each of these factors may vary dramatically between
individuals. While you don't have control over these factors, understanding them can help you in your search for the proper
acne treatment. Acne Causes - Culprit #1: Hormones.
For the majority of acne sufferers, the trouble begins at puberty, when the body begins to produce hormones called androgens.
These hormones cause the sebaceous glands to enlarge, which is a natural part of the body's development. In acne sufferers,
however, the sebaceous glands are overstimulated by androgens, sometimes well into adulthood. Androgens are also responsible
for acne flare-ups associated with the menstrual cycle and, on occasion, pregnancy. Acne Causes - Culprit #2: Extra
sebum. When the sebaceous gland is stimulated by androgens, it produces extra sebum. In its journey up the follicle
toward the surface, the sebum mixes with common skin bacteria and dead skin cells that have been shed from the lining
of the follicle. While this process is normal, the presence of extra sebum in the follicle increases the chances of clogging
— and can cause acne. Acne Causes - Culprit #3: Follicle fallout.
Normally, dead cells within the follicle shed gradually and are expelled onto the skin’s surface. But in patients with
overactive sebaceous glands — and in nearly everyone during puberty — these cells are shed more rapidly. Mixed
with a surplus of sebum, the dead skin cells form a plug in the follicle, preventing the skin from finishing its natural process
of renewal. Acne Causes - Culprit #4: Bacteria. The bacterium
Propionibacterium acnes, (P. acnes for short) is a regular resident of all skin types; it’s part of the skin’s
natural sebum maintenance system. Once a follicle is plugged, however, P. acnes bacteria multiply rapidly, creating the chemical
reaction we know as inflammation in the follicle and surrounding skin. Acne Causes - Culprit #5: Inflammation.
When your body encounters unwanted bacteria, it sends an army of white blood cells to attack the intruders. This process is
called chemotaxis; or, simply put, the inflammatory response. This is what causes pimples to become red, swollen and painful.
The inflammatory response is different for everyone, but studies have shown that it is especially strong in adult women.
What can I do?
Fortunately, you have options! There are many kinds of acne treatments available today. But first, you should
try to determine the type and severity of your condition. Acne, like a person, is highly individual — it can take
many forms, and have a highly variable response to treatment. The more you know about your specific form of acne,
the more likely you are to find a treatment that works for you.
