How Does Sunscreen Work? (+ 9 Other Sunscreen FAQs)
Sunscreen works by absorbing UV rays from the sun and converting them to heat energy that is either radiated from or absorbed into the skin.
KEY TAKEAWAYS
- Sunscreen is an essential part of daily skincare that shouldn't be overlooked
- All sunscreen (whether it contains organic and inorganic filters) works the same way
- You should protect yourself from the sun by wearing sunscreen, protective clothing, and a hat, and seek shade to avoid the sun when it is at its harshest
Sunscreen should be an essential component of your daily skincare regime.
Unfortunately, there’s so much misinformation about the importance of sunscreen (especially in the colder months), how sunscreen actually works, choosing the right sunscreen for you, and how much sunscreen should be applied and when.
Most of us slather it on without a care in the world, never pausing to wonder what goes in it. Whether you're confused about the difference between mineral and chemical sunscreen, what SPF and broad spectrum mean, whether you can use sunscreen if you have allergies and if it's safe in general, we've got the answers you seek.
We’ve enlisted the expertise of Dr Scott McGregor, We Are Feel Good Inc. Co-Founder and Skin Cancer & Cosmetic Physician, to explain how sunscreen works as well as answer some of the most frequently asked questions that we encounter.
1. How Does Sunscreen Work?
'How does sunscreen work' is probably the question we get asked most often when it comes to sunscreens. It all comes down to the ingredients and what they do.
Sunscreen ingredients have two main components: the active ingredients and the emulsion. Most sunscreens have anywhere between one and six active ingredients that provide sun protection in the form of UV filters (stay tuned for more on these later). The emulsion is what the active ingredients go in, such as a lotion, cream, or oil. It helps to preserve the product, give it water resistance, and affects the smell, texture, and how it sits on the skin.
Broadly, there are two different types of sunscreen: physical (also called mineral) and chemical (also called organic sunscreens. These two types of sun protection have different active ingredients, and many people believe that they work in different ways. However, according to Dr McGregor, "All sunscreens work essentially the same way. The UV filters used absorb ultraviolet light and convert it to heat."
This very low level of heat energy is then either radiated from or absorbed into the skin, hence UV filters are also called UV absorbers. You may hear the active ingredients in physical sunscreens referred to as UV reflectors. Though this reference isn't entirely correct, as Dr McGregor explains:
There is a widely held myth that physical sunscreens work differently than chemical sunscreens by creating a physical barrier to reflect UV rays.
Current research on sunscreen choice shows that while mineral sunscreens do create a barrier that to some extent reflects or scatters UVA and UVB rays away from the skin's surface, physical UV filters such as zinc oxide perform in mostly the same way that chemical sunscreen ingredients do. Studies into metal oxide sunscreens have shown that physical sunscreen reflects just 4-5% of UV rays, while absorbing the rest like chemical sunscreen does.
Ultimately, both chemical and physical sunscreen work the same way i.e. they prevent skin damage and protect skin cells by absorbing UV radiation from the sun and converting it to heat that is then released harmlessly.
2. What is the Difference Between Physical and Chemical Sunscreen?
When it comes to physical vs chemical sunscreen the difference comes down to the sunscreen's active ingredients i.e. the UV filters. "There are broadly two types of filters: organic chemical filters, and inorganic, 'physical' filters (like Titanium Dioxide)," says Dr Mcgregor.
Chemical formulas of sunscreen use a combination of organic chemicals that contain carbon and act as UV filters. Most sunscreens currently available are chemical sunscreens. Organic UV filters are also known as chemical filters because the molecules within them change to prevent ultraviolet radiation (UV radiation) from penetrating the skin.
Physical sunscreen is carbon-based and uses inorganic filters (i.e. minerals) including Titanium Oxide, Titanium Dioxide, and Zinc Oxide as UV filters. Physical sunscreens are marketed as being 'all natural’, but this is misleading. These elements may occur naturally on earth but they still need to be processed in a lab to work in sunscreens.
Chemical (or organic) sunscreens tend to be a more lightweight formula and more durable than physical sunscreen, meaning that they typically last longer and are easier to apply.
However, modern formulations (like the Mineral Sunscreen SPF50+ from We Are Feel Good Inc.) are becoming increasingly popular as they are more lightweight and have reduced 'white cast' i.e. a pale film that older formulations often leave making them unsuitable for dark skin. Mineral formulas are often more popular for sensitive skin as they have less sunscreen ingredients that may cause a potential reaction or irritation.
3. Why is Sunscreen Important?
"Every 30 minutes someone in Australia is diagnosed with Melanoma and it is the number one cancer for those aged 20–39," says Dr McGregor.
Those are some scary statistics! Here's another for you - a massive 80% of skin aging is due to sun exposure. The damage is cumulative, and in Australia, unprotected skin can experience sun damage in as little as 10 minutes in the sun.
Using sunscreen every morning should be an essential part of your daily skincare routine, says Dr McGregor: “I spend my day dealing with the damaging effects of the sun. I have advocated for the daily use of SPF 50+ sunscreen for many years as the best way to prevent premature aging of the skin and skin cancers."
4. How Often Should You Reapply Sunscreen?
It is recommended that sunscreen be applied at least 20 minutes before sun exposure, but when you should reapply depends on what you're doing while wearing it.
"Sunscreens should be reapplied after swimming or any activity that causes sweating," says Dr McGregor. "For a day at the office, generally I would reapply at lunch time if entering the sun, unless you have sunscreen under your makeup and the make up is still in place."
When reapplying, be sure to cover all exposed areas, including face, neck and back of hands. Even if you're driving in the car or sitting in an office, you need to protect these areas as windows don't block harmful UV radiation.
"Also, a lot of people don’t apply sunscreens liberally enough or reapply when they should, which affects protection,” Dr McGregor says. Contrary to one of the most common sunscreen myths, applying a minuscule amount just once per day is not good enough and won't protect skin adequately.
For each application you should use a minimum of 5mL (i.e. around a teaspoon) for your face, neck, each leg and arm, and front and back torso, totalling 35mL (i.e. around 2.5 tablespoons).
To work properly, a sunscreen needs to be spread evenly and settle onto the skin. Anything that might disrupt this will make the protection less effective, such as uneven application or not allowing time to settle before swimming etc.
5. How Do You Choose the Right Everyday Sunscreen?
The right everyday sunscreen for you, according to Dr McGregor, is "the one that you feel good enough about using every day."
Sunscreen is a very personal choice, as it depends on a number of different factors, such as if you have any sensitivities and what you will be doing when you wear it.
Dr McGregor does offer some further advice to help narrow it down: "Choose an SPF 50 if possible. For sporting and active days, choose a water resistant sunscreen. Otherwise, it really is a matter of personal choice."
We Are Feel Good Inc's Broad Spectrum SPF 50+ Sunscreen range has many sunscreens that are formulated to suit all skin types (including sensitive skin, dry skin, and even baby skin). All of our SPF50+ range is water resistant, provides SPF 50 minimum sun protection, and is dermatologically tested.
6. What Does Broad Spectrum Mean?
If a sunscreen is labelled broad spectrum, this means that the sunscreen protects you from both UVA and UVB rays.
It is important to protect your skin from both forms of UV radiation as they affect your skin (and health) in different ways. UVB rays have the largest effect on the top layer of skin and cause redness or burning with prolonged sun exposure.
UVA rays reach deep into the layers of the skin and cause deeper sun damage, aging and wrinkling. Both can cause skin cancer. In simple terms, think of the A in UVA as for 'aging' and the B in UVB as for 'burning'.
Would be good to have a graphic showing how the rays affect your skin like this
Given that it blocks both types of rays, naturally broad spectrum protection is the best available. "Use a broad spectrum sunscreen every day, even when cloudy," Dr McGregor recommends.
7. What Does SPF Mean?
SPF stands for Sun Protection Factor. It measures how quickly the sun's rays will turn your skin pink, or cause sunburn. It is related to UVB radiation (remember, B is for burning), and the number refers to how many times longer it will take you to burn as opposed to without sunscreen.
The higher the number, the greater sun protection it offers. For example, an SPF 50 sunscreen that is applied and reapplied as directed means you will be safe from sun damage 50 times longer than if you weren't wearing any sunscreen.
So what SPF should you use? Opt for SPF 50 as a minimum, says Dr McGregor: "You may be thinking that an SPF15 and an SPF50, there's not a lot of difference, and maybe an SPF15 is enough.
But an SPF50 gives you that extra bit of insurance that if you haven't applied it 100% correctly, you're going to get a lot more coverage. That's why, in Australia, we always say that an SPF50 is much safer."
8. What Else Should I Do to Protect My Skin From the Sun?
In simple terms, the easiest way to protect your skin from the sun's damaging UV rays outside of applying sunscreen regularly is to "cover up,'" according to Dr Mcgregor.
That means that anytime you venture outside when UV levels are 3 or above, you should wear protective clothing including a wide-brimmed hat, sunnies, and a lightweight, long-sleeved shirt (if you can stand the heat).
We know it can be tough when the weather’s so good, but try to limit the amount of time you’re in the sun between 10am and 4pm, as this is when the sun's rays are the most intense. If you do find yourself outside during these times, seek shade where possible, apply sunscreen regularly, and apply these after sun care tips once you're back indoors.
9. Is Sunscreen Safe?
In Australia, a sunscreen that guarantees SPF protection undergoes rigorous testing by the Therapeutic Goods Association in order to prove that the protection advertised can be guaranteed.
The TGA is a government body that regulates the industry and monitors the latest research data in the safety and efficacy of ingredients used in sunscreens. Any TGA listed sunscreens are certified 100% safe for consumers.
When choosing a sunscreen, look for one which has an Australian License Number printed on the front of the bottle, "AUSTLXXXXXX" to ensure that it is TGA approved. Every We Are Feel Good Inc. sunscreen is TGA approved and safe to use.
10. Can I Use Sunscreen if I Have Allergies?
You can use sunscreen if you have allergies, in fact you must, to protect your skin from sun damage. It is estimated that just 1% of the population may react to sunscreens. This reaction may be a red rash that comes on after the cream is applied, or develops once exposed to the sun.
Reactions from sunscreens may be caused by a variety of factors including reactions to the UV filters, preservatives, fragrances, or other common ingredients including Vitamin E, Aloe Vera and Beeswax which are used in many cosmetics.
We Are Feel Good Inc.'s Sensitive Sunscreen SPF50+ is designed specifically for those with sensitive skin. It has "a combination of powerful anti-inflammatory and anti-oxidant rich ingredients, to help reduce skin inflammation and protect from environmental factors," says Dr McGregor. "It also contains no fragrance, meaning less skin irritation, and contains none of the traditional preservatives that are known to irritate some skin types."
Before applying a new product, Dr McGregor says you should always patch test on a small area of skin such as your inner upper arm or thigh. Leave it on for at least a few hours and note any possible reactions.
