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What are the short-term and long-term effects of sun exposure?

A walker against a blue sky
Bupa GP
29 May 2024
Next review due May 2027

As the days get longer and we enter the summer months, it can be enjoyable to enjoy time outdoors in the sun. But even on cloudy days, we’re exposed to ultraviolet (UV) radiation. This is a type of radiation that comes from the sun. Being out in the sun increases the amount of UV light we’re exposed to, and this can affect our health. Here, I discuss the effects of sun exposure and how to stay safe in the sun.

people enjoying the sun outdoors

How does sunlight affect your body?

Sun exposure can be good for us in moderate amounts. Sunlight is our main source of UV radiation, and UV radiation helps our bodies make vitamin D. Vitamin D keeps our bones, muscles, and teeth healthy. Most vitamin D is produced from the exposure of our skin to UV radiation.

It’s thought that 10 to 15 minutes of exposure to sunlight should give you enough vitamin D, while keeping your risk of sunburn low.

For people with darker skin, 25 to 40 minutes should be safe. But regardless of how much time you spend in the sun, it’s important to wear sun cream.

You may have read some myths about sun cream  – including that it makes you deficient in vitamin D. But there’s little evidence that this is the case.

Too much sun exposure can increase your risk of cancer, as well as damage your skin and eyes. The amount of UV radiation you’re exposed to will vary depending on factors such as:

  • time of day – UV rays are at their strongest between 10am and 4pm
  • time of year – UV radiation is highest during the summer
  • altitude (height above sea level) – at higher altitude, you’re exposed to more UV radiation
  • cloud cover – heavy clouds can reduce the amount of UV radiation that reaches the ground
  • reflection – sand, snow, and water all reflect sunlight, which can increase your exposure

When should I avoid sun exposure?

The effects of the sun vary from person to person, but anyone can get sunburnt. Your risk of burning depends on how sensitive your skin is, and the strength of UV radiation that day. The UV index is a helpful way of knowing how strong that day’s UV rays are. The higher the index number is, the higher the risk of sunburn.

Some people should take extra care in the sun because their risk of sunburn is higher. These include people with:

  • fair skin
  • lots of moles or freckles
  • light coloured hair or eyes
  • a history of sunburn or family history of skin cancer

Your skin’s sensitivity to sunlight is linked to the amount of melanin in your skin. This is a pigment that your skin makes in response to sun exposure and is what gives some people a tan.

What are the short-term effects of sun exposure?

Being in the sun for short amounts of time can be good for your vitamin D levels. But spending too long in the sun, without protecting yourself, can lead to some unwanted side-effects.

One of the main short-term effects of sun exposure is sunburn. This is when your skin becomes red after being in the sun, and it can blister or peel. Sunburn is a form of skin damage. Even if you tan, the increase in melanin is also a sign of skin damage. Although the effects of sunburn may be short-lived, a history of sunburn increases your risk of skin cancer.

Exposure to UV reflections from snow, ice, sand, or water can also damage your eyes. This causes a condition called photokeratitis. It’s sometimes called ‘snow blindness’ because it often affects people at high altitude, who are exposed to the reflections of UV radiation from snow. Photokeratitis can cause painful and swollen eyelids and hazy vision. Symptoms of photokeratitis normally go away within a couple of days.

What are the long-term effects of sun exposure?

While the short-term effects of sun exposure might go away within a few days, there are longer-term effects to think about.

The main long-term effect of sun exposure is skin cancer. Sun damage is the cause of most skin cancers. There are two main types of skin cancer that can be caused by sun exposure:

  • non-melanoma skin cancer – these cancers tend to develop where your skin has been exposed to sun
  • melanoma skin cancer – these cancers begin in the cells that produce melanin (melanocytes) and are less common than non-melanomas

Sun exposure can also lead to premature aging, even many years after a sunburn or suntan. This means that your skin becomes wrinkled and leathery before it naturally would. Exposure to UV light without eye protection can also increase your risk of cataracts and some eye cancers.

How can I stay healthy in the sun?

There are lots of steps you can take to stay safe in the sun. These mainly include limiting your exposure or protecting yourself against UV rays, especially if the UV index is 3 or higher. In the UK, this usually happens between mid-March and mid-October. Here are some tips to limit sun damage.

  • Use sunscreen. Try to use sunscreen with at least SPF 30, and keep re-applying it throughout the day. Especially if you’ve been swimming – not all sunscreen is water-resistant.
  • Seek shade. Sunscreen can’t provide full protection from the sun, so try to stay in the shade when you can.
  • Cover up. The less skin that’s exposed to the sun, the less likely it is to burn.
  • Protect your eyes – wear sunglasses that provide UV protection.
  • Avoid the midday sun, as this is when the sun is at its strongest.

Infographic: Five ways to stay safe in the sun

Bupa's sun safety infographic (PDF, 0.4 MB), illustrates five ways to stay safe in the sun.

 


An infographic explaining how to stay safe in the sun

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A walker against a blue sky
Sonal Kumar
Bupa GP

 

Co-author

Sheila Pinion, Health Content Editor at Bupa UK

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