Sun Protection & Anti-aging

By: Ms Doreen Ng, Pharmacist at Unity Tiong Bahru

First seen in Lifestyle Magazine (April 2013), pg 93. This article is an unbreached version of the print edition.


Sunlight has a profound effect on the skin, causing premature skin aging, skin cancer, and a host of skin changes. These effects are mainly caused by ultraviolet (UV) rays, which is an invisible kind of radiation that comes from the sun.

There are 3 kinds of UV rays:

  • UVA – Accounts for up to 95% of the UV rays that reach the Earth's surface, and penetrates deeper into the skin, causing tanning. Fairly constant intensity throughout the day and year.

  • UVB - Affects the outer layer of skin, the epidermis, and is the primary agent responsible for sunburns. Most intense during the hours when the sun is the brightest.

  • UVC – Almost completely absorbed by the ozone layer and does not reach the ground.

How does sunlight damage our skin? What kind of symptoms does it cause?

Both UVA and UVB exposure can cause damage to the skin, accounting for up to 90% of the symptoms of premature skin aging. However, the actual mechanisms involved are not fully understood yet. Some proposed mechanisms include:

  • Collagen breakdown
  • Free radicals and DNA damage
  • Cell death

Chronic exposure to UV rays can lead to skin aging and damage, including:

  • Fine lines and wrinkles
  • Age spots, freckles, skin discolourations and pigmentations
  • Coarse, scaly, loose dry skin
  • Scaly red patches, otherwise known as actinic keratoses
  • Tough leathery thick skin that is rough and dry

How do I protect myself against harmful UV rays?

UV rays can reach you anytime of the day, not just on bright and sunny days. Hence, we need to protect ourselves from these harmful UV rays throughout the year, even on cloudy or hazy days. UV rays also reflect off of surfaces like water, cement, sand, and snow. Some tips to protect yourself from these harmful rays are listed below.

  1. Avoid peak sun hours

    • Seek shade during the hottest part of the day, usually from 10 a.m. to 4 p.m., when the sun's rays are at their most intense.

  2. Wear protective clothing to limit UV exposure

    • Loose-fitting long sleeve tops and long pants that are made of tightly woven material offer more protection from the sun.

    • Bright- or dark-colored, lustrous clothes may also reflect away more UV rays than pastels and bleached cottons.

    • Wear broad-brimmed hats to help shield your face, ears and neck area.

    • Wear sunglasses that can block both UVA and UVB rays to protect your eyes.

  3. Avoid indoor tanning

    • Indoor tanning can cause just as much or even more damage compared to sunlight as tanning machines also emit UV rays.

  4. Sunscreen

    • Apply sunscreen liberally, even on cloudy or cool days to protect against UV rays, at least 30 minutes before sun exposure.

    • Anyone above the age of 6 months is recommended to use sunscreen.

There are so many types of sunscreen available in the market. What should I look out for?

A broad spectrum sunscreen should ideally protect against both UVA and UVB rays. Most products combine several ingredients in order to achieve this. There are two general classes of sunscreens, chemical and physical sunscreens.

  • Chemical sunscreens – Work by absorbing UV rays. Common examples include Aminobenzoic acid derivatives (PABA), Avobenzone, Salicylates, Cinnamates and Benzophenones.
  • Physical sunscreens – Work by reflecting and scattering UV rays. Common examples include Titanium dioxide and Zinc oxide.

It is important to note that sunscreens do not filter 100% of UV rays. Most sunscreens include their Sun Protection Factor (SPF), which is an indication of how much protection it provides against UVB rays. SPF measures how long it will take for one’s skin to redden when using a sunscreen compared to when one is not using the sunscreen. For instance, if it normally takes 10 minutes for you to sunburn without a sunscreen, applying a sunscreen with an SPF of 15 will delay the onset of a sunburn to 150 minutes. However, this also depends on many other factors, such as intensity of the UV rays, whether the sunscreen’s effectiveness remains after time, etc. The higher the SPF, the more protection it provides. A sunscreen with an SPF of 15 screens 93 percent of the sun's UVB rays, while one with an SPF of 30 protects against 97 percent. Generally, an SPF of 30 is sufficient for people with sensitive skin or who spend a lot of time outdoors.

However, SPF gives no indication of UVA protection. There is currently no standard measurement of a sunscreen’s effectiveness in blocking UVA rays. Do look out for sunscreens which indicate ‘broad spectrum’, ‘multi-spectrum’ or ‘UVA/UVB protection’.

How should I apply sunscreen?

Sunscreen should be applied to dry skin about 30 minutes before sun exposure to ensure that it is sufficiently absorbed. A common mistake made by most people is that they apply too little sunscreen. This can reduce the effectiveness of the sunscreen. About one ounce (5-6 teaspoons) is recommended to cover the entire body on average. Be extra careful to cover thin-skin areas such as your face, nose, ears, neck and, for sandal-wearers, the tops of feet. Do also remember to get a lip balm or lipstick with adequate SPF to protect your lips.

It is also important to reapply sunscreen every 2 hourly, especially if you are staying outdoors for an extended period of time. Also consider reapplying after periods of prolonged sweating, abrasion or water sports. If possible, apply to dry skin and allow for 20 to 30 minutes before resuming activity.