Sun Protection Introduction
The sun’s ultraviolet radiation contributes to skin ageing. This means that having good sun protection also has an added cosmetic benefit. We know there is concern and controversy about vitamin D, which we address further down.
Sun protection should have a particular focus during the hotter months (September to May). But you can do damage to your skin on a cloudy day and even during winter.
As an example:
- with a UV index rating of 3, it will take about one hour for a fair-skinned individual to develop DNA damage. Incidentally, this is the level at which the World Health Organization (WHO) says is safe (we disagree that below 3 is safe)
- in winter, Auckland has a UV index of about 1.8. At this level, it would take about 100 minutes of exposure to develop DNA damage.
We know that many kiwis spend prolonged periods outside on mild winter days thinking that they are safe from UV damage. It is important to know that there is no safe UV level.
We recommend daily sunscreen use all year round.
Duration until DNA damage at June peak UV
|Region||June peak UV index||Time until DNA damage (mins)|
Minutes until DNA damage is estimated for those with fair skin. For individuals with darker skin, the duration will be longer.
Are you just crazy, over-the-top dermatologists?
Not the last time we checked … but studies have shown that daily sunscreen use reduces the risk of:
Every day we see the devastation of skin cancer – we are trying our best to reduce New Zealand’s skin cancer burden, and essentially put ourselves out of business.
In the studies, daily sunscreen use was compared to incidental sunscreen use which is how most people use it. Incidental use is only using sunscreen when people feel they need to (e.g., going to the beach, doing the gardening, etc).
UV Damage is dependent on several factors
- The intensity of ultraviolet irradiation reaching you (UV index) which includes cloud cover.
- Your duration of exposure.
- Your susceptibility – which includes your skin type (how fair or dark your skin is).
There is no safe UV Index level. Sunlight is a carcinogen.
The WHO currently recommends sun protection when the UV Index is over 3. Please note that this level was chosen without evidence. Clearly, a UV index below 3 is a lower risk than a UV level above 6, however, there is no safe UV Index level. Several studies have shown that DNA damage develops when the UV index is below 3. As discussed above, daily sunscreen use has also reduced the development of skin cancers in real-life studies.
Strategies for sun protection:
Several scientists involved in UV research have requested that the WHO update their recommendations.
- Hats are important to protect from skin cancers on the scalp, especially for those who are starting to thin on top.
- Sunglasses not only help to reduce the risk of cataracts but can help reduce the risk of skin cancer around the eyelids. We don’t know anyone who routinely puts sunscreen on their eyelids!
- Seek shade and avoid the peak UV times of 11 am to 4 pm.
- UV-protecting clothing – ideally these are tightly woven, long-sleeve items. Some clothing items are now labelled with a UV protection factor.
- Sunscreen is an important component of sun protection.
You CAN do DNA damage without getting sunburnt.
Again, studies have demonstrated that DNA damage can occur, even when sun exposure does not result in sunburn. These studies have also shown that this DNA damage persists. The persistence of DNA damage does depend on the pattern of sun exposure, frequency, and extent of DNA damage. Low-level, infrequent DNA damage will often be repaired by the body – but why take the risk of developing skin cancer and needing surgery?
Sun protection shouldn’t be about preventing sunburn, but about preventing DNA damage.
Will sun protection make me vitamin D deficient?
Vitamin D is important for health, however, most people will still produce adequate vitamin D from sunlight over summer. However, in winter it is likely most people in New Zealand will end up with vitamin D deficiency without supplementation. The stores of vitamin D built up over summer generally only last about two months.
We know there are a lot of claims about people needing a minimum amount of sun exposure for vitamin D. This is simply not true.
There is no minimum amount of sun exposure required for vitamin D.
We recommend that people protect themselves from the sun (which is a carcinogen) and take a vitamin D supplement instead if required – please check with your doctor. After all, New Zealand has been labelled the melanoma capital of the world. We need to be better at our sun protection, seriously!
Furthermore, most people with pigmented skin will be vitamin D deficient in New Zealand and will find it very difficult to maintain vitamin D levels without supplementation.
We also discuss some aspects of Vitamin D on our sunscreen page.
Vitamin D requirements (estimated)
|Age||Amount (µg/day)||Amount (IU)|
|> 70 yrs||15-20||600-800|
Unfortunately, we have an incomplete understanding of vitamin D biology and metabolism. Some professional societies and organisations recommend amounts up to double. Vitamin D absorption can be variable between individuals so it is difficult to provide a blanket recommendation that will suit everyone. We recommend consulting your doctor for advice.
Will sun protection limit my healthy glow?
There is nothing healthy about a tan. Tanning is essentially a protective response to UV irradiation and DNA damage. We don’t understand why people have a perception that irradiating their skin is healthy.
We don’t have any concerns about fake tan products, as these have been demonstrated to be safe.
Sunscreen for sun protection
In theory, an SPF 30 sunscreen is adequate, however, most people (dermatologists included) don’t apply sunscreen thick enough to achieve the protection level measured in a lab environment – who wants to look like a ghost? As such, we recommend an SPF 50+ sunscreen to provide an extra safety margin to compensate for real-life usage.
It is also important to ensure that the sunscreen you use provides broad-spectrum protection which will also protect against UVA radiation, not just UVB. If you are undertaking activities where you sweat or get wet, it is important to ensure that the sunscreen is water-resistant.
Sunscreen should be applied liberally to all potential sun-exposed areas at least 30 minutes before exposure as it can take this long for it to be absorbed into the skin. Sunscreen ideally should be reapplied every two hours, and immediately after getting wet. This recommendation even applies to sunscreens that are rated as active for longer than two hours such as ‘day-long’ products.
- McKenzie, R.L., & Lucas, R.M. Reassessing Impacts of Extended Daily Exposure to Low Level Solar UV Radiation. Sci Rep 8, 13805 (2018). 10.1038/s41598-018-32056-3
- McKenzie, R. (2017). UV radiation in the melanoma capital of the world: What makes New Zealand so different? doi: 10.1063/1.4975499
- Van der Pols, J. C., Williams, G. M., Pandeya, N., Logan, V., & Green, A. C. (2006). Prolonged Prevention of Squamous Cell Carcinoma of the Skin by Regular Sunscreen Use. Cancer Epidemiology Biomarkers & Prevention, 15(12), 2546-2548. doi: 10.1158/1055-9965.epi-06-0352
- Green, A. C., Williams, G. M., Logan, V., & Strutton, G. M. (2011). Reduced Melanoma After Regular Sunscreen Use: Randomized Trial Follow-Up. Journal of Clinical Oncology, 29(3), 257-263. doi: 10.1158/1055-9965.epi-06-0352
- Marks, R. (1995). The Effect of Regular Sunscreen Use on Vitamin D Levels in an Australian Population. Archives of Dermatology, 131(4), 415. doi: 10.1158/1055-9965.epi-06-0352
- Young, A. R., Sheehan, J. M., Chadwick, C. A., & Potten, C. S. (2000). Protection by Ultraviolet A and B Sunscreens Against In Situ Dipyrimidine Photolesions in Human Epidermis is Comparable to Protection Against Sunburn. Journal of Investigative Dermatology, 115(1), 37-41. doi: 10.1046/j.1523-1747.2000.00012.x
- National Institutes of Health. Vitamin D: Fact Sheet for Health Professionals. 12 Aug, 2022; National Institutes of Health
- Nutrition Foundation. Vitamin D. 26 Jan, 2022; Nutrition Foundation