woman seated on textile applying suncsreen
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How Does Sunscreen Protect Your Skin?

You know that sunscreen is hands down the most effective way of protecting your skin from the harmful effects of the sun, right? Well, even if you do, you need to understand the science behind sunscreen. Next time you apply sunscreen, you’ll appreciate the good things you’re doing for your skin.

Ultraviolet (UV) rays from the sun are the main culprit behind sunburns, skin ageing, and even skin cancer. Sunscreen contains active ingredients that absorb, scatter or reflects UV rays, providing an extra layer of defence for our skin. Understanding the different types of UV rays and how sunscreen protects us can help guide our decisions when choosing an appropriate sunscreen product.

Basics of Sunscreen Protection

Let’s learn about sunscreen protection basics, its capabilities, and its limitations.

UVA and UVB Rays

Ultraviolet (UV) rays from the sun are divided into UVA and UVB. Both types can cause skin damage, premature ageing, and increase the risk of skin cancer. UVA rays penetrate deeper into the skin, causing damage to collagen and elastic fibres. In contrast, UVB rays are responsible for sunburns and are crucial in developing skin cancer.

Sun Protection Factor (SPF)

Sun Protection Factor (SPF) measures how well a sunscreen can protect against UVB rays. It is important to note that no sunscreen can block 100% of UVA and UVB rays. Higher SPF values provide better protection, but the differences become minor as the SPF value increases. Here’s a quick overview of SPF values and their level of protection:

SPF ValueUVB Rays Blocked1593%3097%5098%

Choosing a sunscreen with at least SPF 30 and one that offers “broad-spectrum” protection is recommended, which means it protects against both UVA and UVB rays. Sunscreen needs to be applied generously and at least every two hours. More if your swimming or sweating a lot.

Types of Sunscreen

There are two main types of sunscreen: chemical and physical. Both types protect from the sun’s harmful UV rays but do this differently.

Chemical Sunscreens

Chemical sunscreens contain organic compounds that absorb UV radiation, which stops them from penetrating the skin. They typically work by converting the harmful UV rays into heat, then dispersed throughout the skin. Some common ingredients in chemical sunscreens include:





Chemical sunscreens are often preferred because they have a lighter, less greasy feel and can provide broad-spectrum protection. However, they can cause skin irritation and may not suit people with sensitive skin.

Physical Sunscreens

Physical sunscreens, or mineral sunscreens, contain inorganic compounds such as zinc oxide or titanium dioxide. These sunscreens work as a barrier, reflecting and scattering UV radiation before it can reach the skin. Critical features of physical sunscreens include:

Long-lasting protection

Less likely to cause skin irritation

More environmentally friendly

The main drawback of physical sunscreens is that they can leave a white cast on the skin, making them less cosmetically appealing. However, recent formulations such as micronized or nanoparticle versions help minimize this issue while providing adequate protection.

Proper Application and Use

How Much to Apply

Applying the right amount of sunscreen is crucial to ensure adequate protection. A general rule is to use about 1 ounce (30 grams) of sunscreen, enough to fill a shot glass, for your entire body. This should cover most adults wearing swimwear.

Apply a generous layer to all exposed skin, including the face, ears, neck, and scalp.

Don’t forget to cover often overlooked areas such as the back of the hands, the top of the feet, and behind the knees.

When to Reapply

Reapplying sunscreen is necessary to maintain its effectiveness, even on cloudy days. Consider the following guidelines:

Reapplication at least every 2 hours while exposed to the sun. After swimming or sweating or towelling off. Even if the sunscreen is water-resistant.

Water Resistance

Water-resistant sunscreens provide protection even when you’re swimming or sweating. However, water resistance is time-limited, so pay attention to the label:

Forty minutes: Sunscreen will maintain its effectiveness in the water for at least 40 minutes.

Eighty minutes: Sunscreen will maintain its effectiveness in the water for at least 80 minutes.

Remember, no sunscreen is completely waterproof, and reapplication after getting wet is essential.

Benefits of Sunscreen

Preventing Skin Damage

Sunscreen acts as a protective barrier on the skin’s surface, shielding it from harmful ultraviolet (UV) rays. The SPF (sun protection factor) present in sunscreens helps determine the degree of protection against UVB rays. By preventing sunburn and cellular damage, sunscreen minimizes the risk of skin damage.

Reducing Skin Cancer Risk

Exposure to UVA and UVB rays has been linked to the development of skin cancer. Sunscreen, particularly broad-spectrum variants, help protect against both UVA and UVB rays. Regular use of sunscreen decreases the risk of skin cancer and helps protect against sunburn, which could lead to skin cancer over time.

Preventing Premature Aging

UV exposure is a significant contributing factor to premature ageing, as it leads to the breakdown of collagen and elastin in the skin. Sunscreen helps to counteract the damaging effects of UV rays, maintaining skin elasticity and reducing the appearance of fine lines, wrinkles, and age spots.

Using sunscreen appropriately is crucial to ensure its effectiveness:

Choose a broad-spectrum, water-resistant sunscreen with an SPF of at least 30.

Apply sunscreen to all exposed skin areas 15-30 minutes before sun exposure.

Reapply sunscreen every 2 hours and after swimming or sweating.

Choosing the Right Sunscreen

With so many sunscreen options available, selecting a product that’s right for your skin type and needs is essential. In this section, we’ll discuss considerations for different skin types and recommendations for children and those with sensitive skin.

For Different Skin Types

Different skin types require various sunscreen formulations for maximum protection and comfort. Here’s a general guideline:

Dry skin: Look for sunscreens with added moisturizers, such as glycerin or lanolin.

Oily skin: Choose oil-free or mattifying sunscreens to prevent an overly shiny appearance.

Combination skin: Find a product labelled as suitable for all skin types, or try a lightweight lotion or gel.

For Children and Sensitive Skin

Children and those with sensitive skin require special sunscreen considerations:

For children: Use sunscreens specifically formulated for kids, as these are usually milder and less irritating. Remember that sunscreen is not recommended for infants younger than six months.

For sensitive skin: Opt for mineral-based (physical) sunscreens containing zinc oxide or titanium dioxide, as they are less likely to cause irritation or allergic reactions.

Remember to check the SPF, broad-spectrum coverage, and water resistance when choosing sunscreen. By matching the right sunscreen to your situation, you can ensure adequate and comfortable protection for your skin.