Can UV Rays Go Through Windows? (house or car windows)

woman tanning at window

Whether you are sitting beside your window while you work or are driving while being exposed to the sun, you might be wondering if UV rays can go through windows. This obviously leads to the concern of the sunlight irritating or burning the skin through the window.

Yes UV rays do go through windows. Though it isn’t always a one size fits all answer. You have different kinds of UV rays some of which penetrate the windows and some that don’t. You also have different kinds of window such as tinted, glass or another material which can make a big difference.

Below we will explain all of this in more detail so you can understand all of the important details.

Understanding UV Rays

Before we get more into the details of how UV rays can pass through a window it’s important we explain UV rays so you can better understand how they work and how they affect the skin.

There are 2 forms of UV rays that we should be thinking about. They are called UVA and UVB.

UVB rays only affect the top layer of our skin and typically are the most common cause for sunburn.

UVA makes up the majority of UV rays on the surface of earth and penetrates into the second layer of the skin called the dermis.

Even though UVB only makes up a small portion of the UV rays they affect our skin and health more than UVA rays.

Can UV Rays Go Through Windows?

As we mentioned earlier yes UV rays do go through windows but how much actually pass through depends on a variety of factors. Typically, lots of forms of glass block at least a portion of UVB rays but not UVA rays.

Can UV Light Go Through Glass?

The first type of window we want to talk about is glass. The same kind of glass that is found in a house or a business building.

These are most commonly doubled layered glass. UV rays pass through the glass primarily in the morning. This is because when the sun gets higher in the midday, the UV rays are coming from above and thus can not enter the window from the same degree, this greatly diminishes the UV rays’ effect by at least 90% at midday and 80% in the afternoon.

In comparison in the morning as the sun rays are more easily passing through the glass the UV rays’ effect are lowered by at least 20%. Also, the further you sit away from the window the more ineffective the UV rays will be.   

Can UV Light Go Through a Car Window?

So, do car windows really block UV? Well, firstly we must consider the types of windows. The windshield in cars is made from laminated plastic which is between 2 layers of glass. The windshield blocks almost all UV rays both UVA and UVB, its protection rate is about 98-99%.

The side windows in a car are typically made from tempered glass. Tempered glass blocks about 60-70% of UVB rays but not UVA rays at all.

Therefore, we can see that UV light does go through car windows – primarily through the side windows as the windshield blocks almost all the UV.

What Should You Do?

After understanding this information it’s important we lay out what you can take from this.

Firstly, you should consider the UV index. The UV index simply is a scale depending on how strong the UV is. If you live in a part of the world that the UV index levels are quite low then this won’t matter much. Though if you live in a sunnier climate closer to the equator this means stronger UV rays, so it’s essential for you. For more information on UV index – what UV index is best for tanning.

For house or business windows – our recommendation is to be weary if you are sitting near a window particularly in the morning (9am-12pm).

If possible pull a blind/curtain to prevent the sun from exposing your skin during this time. It would also be a wise idea to wear sunscreen. In this case go for at least a 20 SPF which should be enough to offer the protection needed.

You can also consider purchasing or have your work purchase a UV window filter which are designed to block and reflect most UV rays.

We Recommend: Biossance Mineral Sunscreen SPF 30

For car windows – You might have seen people who work in jobs where they drive regularly, where their skin noticeably looks worse on one side. This is because the sun rays entering from the side window which they are sitting on is not protecting them enough.

Our recommendation for drivers is to at least wear a low SPF sunscreen of 20. If you are someone who drives as part of their job, we highly recommend a stronger SPF of 50.

If you are driving over a period of 8 hour or more, we also recommend a 2nd application about halfway through your day. It’s important to protect your skin because the side windows in most cars are letting quite a lot of UV rays through.

We Recommend:

Sunscreen: Thrive Natural Body Mineral Sunscreen SPF 50

UV window Filter: KESPEN Anti UV Film

Related Questions –

Can You Get Vitamin D Through a Window?

UVB rays are the ones that cause the body to produce vitamin D. Typically depending on the type of glass at least some UVB rays pass through, though often not too much. This means that you can get vitamin D through glass through in theory the levels will be much lower than being outside and in direct contact with the sunlight.

Can You Get a Sunburn Through a Window?

Yes you can get a sunburn through a window depending on the type of window. Some windows let through a lot more UV rays than others and thus some you can get sunburnt through.

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