Everyone knows exposing your skin to the sun for too long can be dangerous. You may think staying inside on a hot day makes it impossible to be exposed to the suns UV rays, but is this actually true? In this blog post, we investigate whether you can get a suntan through a window by looking at how sun rays actually work and whether you could actually get some health benefits sitting by the window, such as increasing your vitamin D levels.
So can you tan through glass? The simple answer is no… but sort of, yes.
How do sunrays work?
Firstly, we need to look at how sun rays actually work... The sun emits UVA, UVB and UVC rays. UVC is the most dangerous, but there’s no need to worry as it doesn’t reach the earth due to being filtered by the atmosphere.
However, UVA can still be extremely dangerous when exposed to the skin for long periods of time. These rays tan and freckle the skin and can lead to serious health problems. Sitting outside in the garden on a sunny day without any sun cream on isn’t good for your skin but surely sitting behind your living room window is fine?
The difference between UVB and UVB rays
UVB rays have a wavelength of between 280-320 nanometres which are able to penetrate into deep skin layers and cause sunburn. UVA rays have a longer wavelength and can penetrate the glass and reach the dermis. A wavelength of between 320-400 nanometers can cause damage to the collagen in the skin, resulting in loss of elasticity and ageing of the skin in the long term. UVA radiation also has a high risk of causing melanoma, a type of cancer that develops from pigment-containing cells (melanocytes), but barely produce sunburn.
How do windows absorb sunrays?
To answer this, we need to look into how windows absorb the sun’s rays. When a window is hit by UVB rays, the glass absorbs around 97 per cent (which is more dangerous and causes sunburn) and 37 per cent of UVA rays which is less harmful.
Is it time to get out the suncream?
So can you actually get a tan through your window? Can you get sunburnt through glass? Is it time to put on sun cream if you sit near a window at work?
The simple answer is no, at least if your window is traditional glass. The glass blocks most of the dangerous UVB rays, which is the sunlight responsible for melanin production, the dark pigment within the skin that converts radiation energy into harmless heat. As some UVA rays do get through glass though, spending long periods of time in the conservatory or by a window means you should take some precautions to protect your skin from the long-term damage from UVA.
You may not tan but you will do damage to your skin long-term. An Everest conservatory can have solar glass which is specifically treated to reduce the suns glare and reflect solar energy entering your conservatory so you can comfortably enjoy the heat in your conservatory. Do you struggle to keep your conservatory cool in the summer?
Does all glass block sunrays?
Of course, there is some glass that allows UV rays e.g. in sunbeds but the ordinary glass which is used for double glazed windows won’t tan the skin. Although, the glass in car windscreens works slightly differently, a plastic layer between the layers of glass blocks all UVB rays and 80 per cent of UVA rays.
Although, the side windows of a car aren’t laminated so let in more UVA rays. In fact, research has shown that people who regularly spend more time in the car over the course of several years are more likely to develop skin cancers on the left side of the body, particularly with cancers that develop gradually over time” (BBC).
Can you absorb vitamin D through glass windows?
The sun’s rays aren’t all bad though, you might not be able to top up your tan by the window but can sunlight produce vitamin D which helps regulate calcium and phosphate which keeps bones, teeth and muscles healthy. It can also help ease chronic pain and prevent the flu.
Did you know?
Over one billion people worldwide are thought to have a Vitamin D deficiency (aim to sit in the sun for 10-30 minutes per day to get the right amount of vitamin D).
Vitamin D is produced when your skin is exposed to sunlight. Although, as already mentioned glass windows block the UVB portion of the ultra-violet spectrum which means you can’t get vitamin D from sunlight through a glass window. So you will need to go outside to increase your vitamin D levels.
It's not all bad though
So as we’ve discovered, you can’t absorb vitamin D through a window and are unlikely to catch a tan but don’t put the blinds down just yet.
The natural light caused by sunshine in your home can make your space appear more spacious, bright and tranquil. With the interior décor benefits also comes the health benefits. The refreshing shine in fact reduces the production of harmful bacteria and organisms that can grow in any home, acting as a natural disinfectant. Did we mention that sunlight can make you more productive around the house?
Placing your ironing board near a window will, believe it or not, make it that little bit more enjoyable. If you work from home or have children that need homework doing, place the desk by a window where there is maximum light. This will help boost energy and improve concentration.
Of course, getting the right amount of sun exposure is also a challenge as too much can make the room hot and uncomfortable. That's why Everest uPVC, aluminium and timber windows have an anti-glare glass option that reflects solar energy and keeps your home at a comfortable temperature. Blinds can also be a great way to regulate the temperature and allow heat in when you choose.