Summer is nearly here. But rather than getting out the sunscreen, some TikTokers are urging followers to chuck it out and go sunscreen-free.

They claim it’s healthier to forgo sunscreen to get the full benefits of sunshine.

Here’s the science really says.

How does sunscreen work?

Because of Australia’s extreme UV environment, most people with pale to olive skin or other risk factors for skin cancer need to protect themselves. Applying sunscreen is a key method of protecting areas not easily covered by clothes.

Sunscreen works by absorbing or scattering UV rays before they can enter your skin and damage DNA or supportive structures such as collagen.

When UV particles hit DNA, the excess energy can damage our DNA. This damage can be repaired, but if the cell divides before the mistake is fixed, it causes a mutation that can lead to skin cancers.

The most common skin cancers are basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). Melanoma is less common, but is the most likely to spread around the body; this process is called metastasis.

Two in three Australians will have at least one skin cancer in their lifetime, and they make up 80% of all cancers in Australia.

Around 99% of skin cancers in Australia are caused by excessive exposure to UV radiation.

Excessive exposure to UV radiation also affects the appearance of your skin. UVA rays are able to penetrate deep into the skin, where they break down supportive structures such as elastin and collagen.

This causes signs of premature ageing, such as deep wrinkling, brown or white blotches, and broken capillaries.

Sunscreen can help prevent skin cancers

Used consistently, sunscreen reduces your risk of skin cancer and slows skin ageing.

In a Queensland study, participants either used sunscreen daily for almost five years, or continued their usual use.

At the end of five years, the daily-use group had reduced their risk of squamous cell carcinoma by 40% compared to the other group.

Ten years later, the daily use group had reduced their risk of invasive melanoma by 73%

Does sunscreen block the health-promoting properties of sunlight?

The answer is a bit more complicated, and involves personalised risk versus benefit trade-offs.

First, the good news: there are many health benefits of spending time in the sun that don’t rely on exposure to UV radiation and aren’t affected by sunscreen use.

Sunscreen only filters UV rays, not visible light or infrared light (which we feel as heat). And importantly, some of the benefits of sunlight are obtained via the eyes.

Visible light improves mood and regulates circadian rhythm (which influences your sleep-wake cycle), and probably reduces myopia (short-sightedness) in children.

Infrared light is being investigated as a treatment for several skin, neurological, psychiatric and autoimmune disorders.

So what is the benefit of exposing skin to UV radiation?

Exposing the skin to the sun produces vitamin D, which is critical for healthy bones and muscles.

Vitamin D deficiency is surprisingly common among Australians, peaking in Victoria at 49% in winter and being lowest in Queensland at 6% in summer.

Luckily, people who are careful about sun protection can avoid vitamin D deficiency by taking a supplement.

Exposing the skin to UV radiation might have benefits independent of vitamin D production, but these are not proven. It might reduce the risk of autoimmune diseases such as multiple sclerosis or cause release of a chemical that could reduce blood pressure. However, there is not enough detail about these benefits to know whether sunscreen would be a problem.

What does this mean for you?

There are some benefits of exposing the skin to UV radiation that might be blunted by sunscreen. Whether it’s worth foregoing those benefits to avoid skin cancer depends on how susceptible you are to skin cancer.

If you have pale skin or other factors that increase you risk of skin cancer, you should aim to apply sunscreen daily on all days when the UV index is forecast to reach 3.

If you have darker skin that rarely or never burns, you can go without daily sunscreen – although you will still need protection during extended times outdoors.

For now, the balance of evidence suggests it’s better for people who are susceptible to skin cancer to continue with sun protection practices, with vitamin D supplementation if needed.

Katie Lee, PhD Candidate, Dermatology Research Centre, The University of Queensland and Rachel Neale, Principal research fellow, QIMR Berghofer Medical Research Institute

This article is republished from The Conversation under a Creative Commons license. Read the original article.

When spring arrives, so do warnings about thunderstorm asthma. But a decade ago, most of us hadn’t heard of it.

So where did thunderstorm asthma come from? Is it a new phenomenon?

In 2016, the world’s most catastrophic thunderstorm asthma event took Melbourne by surprise. An increase in warnings and monitoring is partly a response to this.

But there are also signs climate change may be exacerbating the likelihood of thunderstorm asthma, with more extreme weather, extended pollen seasons and a rise in Australians reporting hay fever.

A landmark catastrophe

The first time many Australians heard of thunderstorm asthma was in November 2016, when a major event rocked Melbourne.

During a late night storm, an estimated 10,000 people were rushed to hospitals with severe asthma attacks. With thousands of calls on emergency lines, ambulances and emergency departments were unprepared to handle the rapid increase in people needing urgent medical care. Tragically, ten of those people died.

This was the most catastrophic thunderstorm asthma event in recorded history and the first time deaths have ever occurred anywhere in the world.

In response, the Victorian Department of Health implemented initiatives, including public awareness campaigns and improvements to health and emergency services, to be ready for future thunderstorm asthma events.

A network of pollen monitoring stations was also set up across the state to gather data that helps to predict future events.

A problem for decades

While this event was unexpected, it wasn’t the first time we’d had thunderstorm asthma in Australia – we’ve actually known about it for decades.

Melbourne reported its first instance of thunderstorm asthma back in 1984, only a year after this phenomenon was first discovered in Birmingham in the United Kingdom.

Thunderstorm asthma has since been reported in other parts of Australia, including Canberra and New South Wales. But it is still most common in Melbourne. Compared to any other city (or country) the gap is significant: over a quarter of all known events worldwide have occurred in Melbourne.

Why Melbourne?

Melbourne’s location makes it a hotspot for these kinds of events. Winds coming from the north of Melbourne tend to be dry and hot as they come from deserts in the centre of Australia, while winds from the south are cooler as they come from the ocean.

When hot and cool air mix above Melbourne, it creates the perfect conditions for thunderstorms to form.

Northern winds also blow a lot of pollen from farmlands into the city, in particular grass pollen. This is not only the most common cause of seasonal hay fever in Melbourne but also a major trigger of thunderstorm asthma.

Why grass pollen?

There’s a particular reason grass pollen is the main culprit behind thunderstorm asthma in Australia. During storms there is a lot of moisture in the air. Grass pollen will absorb this moisture, making it swell up like a water balloon.

If pollen absorbs too much water whilst airborne, it can burst or “rupture,” releasing hundreds of microscopic particles into the air that can be swept by powerful winds.

Normally, when you breathe in pollen it gets stuck in your upper airway – for example, your nose and throat. This is what causes typical hay fever symptoms such as sneezing or runny nose.

But the microscopic particles released from ruptured grass pollen are much smaller and don’t get stuck as easily in the upper airway. Instead, they can travel deep into your airways until they reach your lungs. This may trigger more severe symptoms, such as wheezing or difficulty breathing, even in people with no prior history of asthma.

So who is at risk?

You might think asthma is the biggest risk factor for thunderstorm asthma. In fact, the biggest risk factor is hay fever.

Up to 99% of patients who went to the emergency department during the Melbourne 2016 event had hay fever, while a majority (60%) had no prior diagnosis of asthma.

Every single person hospitalised was allergic to at least one type of grass pollen. All had a sensitivity to ryegrass.

Is thunderstorm asthma becoming more common?

Thunderstorm asthma events are rare, with just 26 events officially recorded worldwide.

However there is evidence these events could become more frequent and severe in coming years, due to climate change. Higher temperatures and pollution could be making plants produce more pollen and pollen seasons last much longer.

Extreme weather events, including thunderstorms, are also expected to become more common and severe.

In addition, there are signs rates that hay fever may be increasing. The number of Australians reporting allergy symptoms have risen from 15% in 2008 to 24% in 2022. Similar trends in other countries has been linked to climate change.

How can I prepare?

Here are three ways you can reduce your risk of thunderstorm asthma:

• stock up on allergy medication and set up an asthma action plan with your GP
• check daily pollen forecasts for the estimated pollen level and risk of a thunderstorm asthma event in your local area
• on days with high pollen or a high risk of thunderstorm asthma, spend less time outside or wear a surgical face mask to reduce your symptoms.

Kira Morgan Hughes, PhD Candidate in Allergy and Asthma, School of Life and Environmental Sciences, Deakin University

This article is republished from The Conversation under a Creative Commons license. Read the original article.