Sunscreen is one of the most important ways to protect your skin’s appearance at any health and age. When used regularly, sunscreen for face and body helps to prevent sunburn, skin cancer, and premature signs of aging. In this article, accredited dermatologist Dr. Teo Wan Lin answers commonly asked questions about sunscreen.
Fact or fiction: should we be using a two-finger length of sunscreen for our face and body? How much sunscreen should I use on my face and body?
The two-finger length is a somewhat arbitrary method of determining the amount of sunscreen that we need. This measurement was proposed in a letter written to the British Medical Journal in 2002, which simply highlights a broad rule of thumb about how we are likely under-applying the amount of sunscreen that we need. In fact, most people only end up applying maybe 25-50% of what’s usually required.
Taking into consideration the recommendation of 2mg per sq cm of skin, in practice, this means using at least a teaspoon worth of sunscreen to cover the face. Studies indicate that most people use too little sunscreen, meaning most are getting sun protection levels much less than the product-stated SPF. Factoring in activities such as swimming or exercising further reduces the amount of sun protection left on the skin. When outdoors, the recommendation is to reapply sunscreen approximately every two hours, or after swimming or sweating.
It is important to be a little bit more conservative in terms of estimating the amount of sunscreen that we are applying. Also, remember not to just rely on sunscreen alone. Rather, sun avoidance measures are probably a much more integral part of sun protection as well. In particular, avoid the sun from 10am to 4pm in an equatorial climate.
Is this the same amount for different types and textures of sunscreen such as cream, gel, lotion and milk?
It is very relevant to talk about the different textures available. The reason is because, first of all, it can affect the subjective perception by the user of how cosmetically acceptable a product is. This may subconsciously influence the amount that they end up applying. For example, in humid climates like in Singapore, we find that we tend to underapply cream or oily versions of sunscreens because it gives the sensation that you’re already applying much more than what you should. In fact, under laboratory settings, to achieve the SPF reflected on the bottle, we should use approximately 2 milligrams per square centimeter of skin. These types of formulations are actually the most effective and the most common.
The thing with gels and lotions is that sometimes it does lower the efficacy of a sunscreen itself. Because, the certain components that protect against UVA, for example, the chemical sunscreens, are only stable in an oil formula. So when it is in a gel or lotion formula, these can eventually contribute to a lower overall SPF value.
Oil in water sunscreens
The exact change in efficacy really depends on the individual formulation, such as the proportion of oil and water components. Oil-in-water and water-in-oil systems are the most commonly available sunscreens and for good reason. They are easy to apply and the oil provides UV absorption. The rule of thumb in applying sunblock is still to stick to the SPF rating which is fixed based on a 2 mg per square centimeter skin application.
The SPF provides a predetermined rating of the amount of sun protection given for the universally fixed amount of application on skin (at 2mg per sq cm). It is independent from the type of formulation, be it gel or lotion etc, which inherently affects the amount of protection given, but not the amount applied. That is fixed on a specific SPF rating. Do note that current FDA regulations on testing and standardization do not pertain to spray sunscreens. The FDA continues to evaluate these products to ensure safety and effectiveness.
What exactly is SPF?
SPF is a measure of how much UV radiation from the sun is required to produce sunburn on skin that is protected by sunscreen. Hence, as the SPF value of the sunscreen increases, there is a proportionate increase in protection against sunburn. The SPF allows the consumer to compare the level of sunburn protection provided by different sunscreens. In dermatology practices, we recommend SPF 30 minimum because of practical issues surrounding reapplication.
Learn more about choosing the ideal sunscreen in our podcast, Dermatologist Talks: Science of Beauty.
Does a high SPF mean I can apply less sunscreen?
Many people believe that wearing a SPF 15 sunscreen allows an individual to stay in the sun 15 times longer without getting sunburnt. This is a very simplistic way of thinking about sunscreens and SPF factor. It is also rather inaccurate. Because, SPF is directly related to the amount of solar exposure that you’re trying to protect your skin from. While it is true that the total amount of solar exposure energy is also related to the duration of solar exposure, there are other factors that influence the amount of solar energy reaching your skin and causing ultraviolet induced damage. For example, the intensity of solar exposure.
The most important thing is that at the end of the day, the American Academy of Dermatology still recommends using sunscreen for face and body in conjunction with sun avoidance measures. Sun avoidance measures are particularly important in a year round tropical climate like equatorial Singapore. From the time of 10am-4pm when the sun is most intense, that’s traditionally what’s recommended in temperate climates. In Singapore’s context, we should be avoiding the sun from 9am all the way to 5pm.
What is the recommended SPF we should wear on a daily basis? How often should it be re-applied for effective protection?
Yes, definitely for daily wear. We live in a year-round tropical climate with high amounts of UV exposure, even indoors, because of windows that do not have UV filters. Dermatologists recommend a minimum of SPF 30. Taking into consideration that the cosmetic preferences of individuals, for example, depending on the texture of the sunscreen, may result in decreased application. For example, if the sunscreen feels uncomfortable or greasy, which are factors that need to be considered.
In general, an SPF 30 blocks 97 percent of the sun’s UVB rays. A higher SPF blocks slightly more of the UVB rays. However, no sunscreen can block 100% of it, so there is little use going for excessively high SPF ratings. In my practice, I typically prescribe an SPF 50. For example, the SunProtector, which uses a lightweight invisible formulation suitable for humid climates.
The SunProtector is exquisitely formulated for humid climates. It is a broad-spectrum sunscreen that also regenerates and soothes sensitive skin. Designed with unique pigments blended to be almost invisible under make-up.
It is also critical to note that a higher SPF lasts the same amount of time as a lower SPF. A high SPF does not allow you to spend additional time outdoors without reapplication. Sunscreen for face and body should be reapplied approximately every two hours when outdoors, even on cloudy days. Furhtermore, after swimming or sweating, as may be instructed on the bottle. In addition, as discussed earlier, one should practise avoiding the sun from 10am to 4pm (in equatorial climates) as much as possible by planning their outdoor activities around it.
Shoul I use a makeup sponge to apply sunscreen? Does it help to apply more evenly?
I don’t recommend this method of dabbing sunscreen onto the sponge. The sponge will definitely lower the efficacy of the sunscreen for face. By virtue of the fact that it is absorbent and is meant for application of makeup. It may even give the false impression – because the sponge gives ‘even coverage’ – that a sufficient amount of sunscreen has been applied. The key thing is the thickness of sunscreen that protects your skin.
I’ve heard that we should apply sunscreen in the direction of the hair’s growth in over to prevent clogging of the pores, is this true?
Unfortunately, this is completely a myth. In terms of skin clogging, the best medical term to describe this would be comedogenicity. Comedogenicity has to do with a few factors. First of all, if the formula itself is heavily oil-based. However, there are oil-based products that are not comedogenic. In fact, it is rare to find a truly comedogenic product both in makeup and skincare in this day and age. Maybe in the early 90s, but rarely in this age. Because of the extensive knowledge of cosmetics and skincare we have now.
The key thing here is also the microenvironment of the skin. For example, if you are wearing sunscreen for face under a face mask, the occlusive nature of the face mask can increase the comedogenicity of the product, even if it’s not comedogenic on its own.
Applying it in a different direction is not a science-based approach. Comedones also do not actually form on the surface of the skin. Instead, they start with an inflammatory process in the deeper layers of the skin – starting as microcomedones before they surface to the top of the skin.
Should I apply more sunscreen for areas on the face with pigmentation or dark spots?
There is no objective scientific evidence that suggests this. Rather, we know that even areas which do not have pigmentation are prone to developing pigmentation. It’s important to note that way before we see pigmentation developing, it’s actually been developing under the skin over many years. My suggestion is to apply as much as you can, and follow the rule that more is always safer when it comes to sunscreen for face. Especially for skin of color, it’s important to look for formulations that do not leave a white cast on your skin.
Is there an ideal method as to how to apply sunscreen on the face and body?
Studies using fluorescence with sunscreens have documented “missing areas” after self-application of sunscreen which is an important consideration when sunscreen fails to protect against sunburn. Techniques of sunscreen application were also tested, and it was found that rubbing instead of gentle application decreased the SPF up to 20%. The latter is therefore recommended to minimise the loss of efficacy during application.
A novel technique for sunscreen application
Notably, a 2014 study described a sunscreen application technique to protect more efficiently against UV radiation. This technique is a systematized method dividing the body and face into different segments so as not to forget any “zones”, which differs from conventional methods. It consisted of three steps.
Namely, step 1 involves the dose of sunscreen (visualization of “teaspoons” to reach the correct amount for each “zone”). Step 2 involves the application itself (applying the total dose on several uniformly spaced spots for each “zone”). Finally, step 3 involves the spread during application (with gentle circular moves for an even application for each “zone”). This sunscreen application technique has been developed for different preparations such as creams, lotions, and sprays. The study showed that it enabled sunscreen to be much more evenly applied.
Furthermore, the skin surface area covered by sunscreen was significantly improved. This method, which has been approved by the French Association of Photodermatology, may provide a useful framework to educate individuals on the proper way of applying sunscreen to improve skin protection from UV rays.
Jeanmougin M, Bouloc A, Schmutz JL. A new sunscreen application technique to protect more efficiently from ultraviolet radiation. Photodermatol Photoimmunol Photomed. 2014;30(6):323-331. doi:10.1111/phpp.12138Tags: ~All Topics, Dermatology, Skincare, Sun Protection