2023 Australia on Balancing the harms and benefits of Sun Exposure

Australian Skin and Skin Cancer Research Position Statement – Balancing the harms and benefits of Sun Exposure 27 January 2023

This is a quick summary of this interesting and informative document. Check out the link below to get the full document.

The effects of exposure to sunlight, particularly the UV wavelengths, are complex and depend on environmental factors (e.g., the intensity of UV radiation; timing, pattern, and total time outdoors) and host factors (e.g., skin pigmentation, immune status). Two main health states are strongly determined by too much or too little exposure of the skin to UV radiation, respectively: skin cancer and vitamin D deficiency. Assessing the balance of harms and benefits of sun exposure requires consideration of all these factors.

They have a very informative guide diagram for recommendations according to risk of skin cancer that is Figure 1. Here’s the link In short this says that if you are at the highest risk of harm protect yourself from the sun when the uv index is > or = 3. Intermediate risk, protect when uv index is > or = 3 if you are in the sunshine longer than needed to maintain vitamin D levels. Lowest risk then routine sunscreen is not required. Protect when outdoors longer than 2hours when UV index is > or = 3.

Here are some additional points the statement makes:

• It is important to expose ample skin to minimise the time outdoors required (and therefore the dose delivered to individual skin cells);

• The time outdoors needed to gain a vitamin D-effective dose is less than the time that will deliver a minimal erythemal dose for all skin types;

• There is little vitamin D production in the early morning and late afternoon/evening

• exposing the eyes to longer wavelengths in sunlight reduces the risk of myopia, influences circadian rhythm, and improves sleep and mood

The report has some interesting data about UV levels for different cities around Australia and then some great indicative times that you would need to be in the sun for in those cities at different times of year in order to generate ‘sufficient’ vitamin D levels.

To compare with NewZealand

Darwin is the only Australian city with uv index year round averaging above 7, Brisbane and Perth averages above 3. We are closest inlatitude to Melbourne (37.8˚S) or Hobart 42.8˚S) – here are these cities uv index averages.

The average UV index for Melbourne shows UV<3 May, June & July; UV Index 3-6 April, August, Sept, October and 7+ November through March. So May-July with 35% of your body exposed you’d need 10 to 20mins between 10-3pm 4 days a week.

In Hobart the average UV index is <3 May to August, 3-6 March, April then again Sept to Nov and above 7 Dec to February. So May to August, exposing 35% of your body 4 days a week you’d need more than 60mins between 10am to 3pm to get your sunshine for vitamin D.

Auckland’s latitude is 36.8˚S,  Wellington 41.2˚S, Christchurch 43.5˚S and Dunedin 45.8˚S

We think this suggests that many New Zealanders just couldn’t possibly get outdoors for the times indicated at the temperatures we have sufficient to generate their vitamin D. So you either use a sunshine machine (like using a walking transport machine but different) or you take a pill (there are other side effects of this that we won’t go into here). Regardless or how you get your vit D it’s clear it’s good for you and we say it should be your choice how you get it.