Sun protection while driving: could long journeys be doing more damage than we think?

Ten hours of driving in summer sun equivalent to one hour of sunbathing, data shows

• Vehicle side windows allow around 11% of UVA to penetrate through glass
• 11 hours worth of driving is enough to cause visible skin damage in those with fair skin
• Expert dermatologist warns drivers of the dangers of sun exposure and the importance of sun protection while driving across the UK and Europe this summer

Planning a big road trip this summer? Whether you’re heading out to the coast or winding through the countryside, one thing you mustn’t forget to pack is your sun protection.

With so much focus on shielding your skin and preventing the dreaded sunburn while out in the open—such as at the beach or on mountain hikes—sun protection while driving (or even merely a passenger) can easily be overlooked.

But did you know that you can still rack up a considerable amount of UV exposure just by sitting in your motorhome?

We've conducted new research into the levels of UVA allowed to pass through glass windows, and the potential risk drivers face during long journeys as a result. We were then able to analyse the data to work out how much damage different journey times could actually be doing to our skin.

As part of our research, we also teamed up Dr. Hamed, an expert dermatologist, who told us more about the risks of sun exposure while driving, and shared his top tips and advice for those planning a summer road trip, either in the UK or abroad.

UV exposure in a motorhome

While being inside a vehicle might feel like a safe haven from the sun, the reality is a little different. Drivers can still face prolonged periods of sun exposure on the road, particularly on long journeys.

Research shows that standard driver-side windows block only around 89% of the sun’s UV rays, which means roughly 11% can still get through. And while that might sound a relatively small amount, it can quickly add up over time.

Let’s look at the numbers.

The average UVI Index (UVI) for a typical summer’s day in the UK is four, and one hour in direct sunlight delivers around four Standard Erythemal Doses (SED). Multiplied over 11 hours, this would total approximately 44 SED, which equates to around four to five Minimal Erythemal Doses (MED). This alone is enough to cause visible skin damage to those with fair skin.

Let’s break it down even further:

So, even a single five hour motorhome journey could be equivalent to 30 minutes of sunbathing or around 1.5-2.5 hours of outdoor walking. And if you’re doing journeys more than five hours long, your potential UV exposure will only increase.

Research shows that prolonged UVA exposure is a major risk factor for photoaging, melanoma and even non-melanoma skin cancer in extreme cases, so it’s vital to understand how much sun you may be exposing yourself and your passengers to.

How to protect yourself from the sun while driving

We spoke to Dr. Hamed, a dermatologist at PowerYourCurls, to learn more about the potential dangers surrounding UV rays and our motorhome windows.

Here’s what he had to say:

What types of UV can reach your skin through a closed motorhome window?

“UVA has a longer wavelength than UVB, so it can go deeper into the skin and also penetrate glass. UVB has higher energy but works on a shorter wavelength, so this can be mostly blocked by a plain motorhome window. If you're exposed to sunlight through a window, it would still affect you less than exposure from direct sunlight; however, for best protection, some kind of UV-blocking film would be ideal. Closed windows will still provide some form of protection from direct sunlight.”

Would you recommend that motorhome owners opt for UV protective windows for their motorhomes? Would you recommend UV-blocking films?

“I would recommend opting for UV protective windows for your motorhome, if it does not come as standard in your motorhome—especially if you are going on long drives or are being exposed to the sunlight in any way. UV blocking films are good for not only protecting against UV damage, but also for helping to keep the interior of the motorhome cool.”

How does this differ from the windscreen? Are you more or less protected from laminated glass in windscreens?

“The windshield is made of laminated glass, which contains a thin sheet of vinyl sandwiched between two layers of glass. This offers much better protection than tempered glass. You're more or less protected by the windshield. This is why people who drive for a longer time tend to get sunburns or aging skin on their forearms as they rest them along the side panels on their doors, rather than on their faces or chest.”

Do you have any tips to avoid getting sunburnt in a motorhome?

“To avoid getting sunburnt in a motorhome, don't drive with the windows down, if you can help it. Also, get some kind of UV protection film, otherwise you'll start to feel the effects pretty easily.”

What are the signs and symptoms of sunburn?

“The initial signs would be redness and the skin feeling warm to the touch. Later, pain, tenderness and possibly even blistering or skin peeling can happen as exposure continues.”

How should I choose what sunscreen to use on a car journey?

“I'd focus on SPF50 if possible, since you'd not have to reapply that as often as the SPF30 versions.”

What should you do if you have been sunburnt whilst driving?

“Use a moisturiser like aloe vera gel or calamine lotion to protect the skin as soon as possible. I've seen people use cold milk or even yoghurt in a pinch. Wear a visor or a wide-brimmed hat, if possible, especially if you need to continue driving. Keep the skin moist by reapplying the aloe vera gel or at least dabbing at your skin with a moist towel to absorb any heat.”

While our motorhomes and other vehicles indeed provide some protection from the sun’s harmful rays, taking extra precautionary steps is always a good idea.

If you’re travelling across Europe, your exposure can be even higher than in the UK. For example, in Spain, the UVI index can reach as high as ten in July, so make sure you’re fully prepared for the sun in whatever country (or countries) you may be passing through on your travels.

Methodology

The above data calculates UVA exposure during road trips by first determining the "UVA Exposure Equivalent" in hours, assuming 11.2% UVA transmission through car side windows. This equivalent time is then converted into Standard Erythemal Doses (SED) by multiplying by 4 SED per hour, based on a UVI of 4, typical of a UK summer day. Finally, estimated Minimal Erythemal Doses (MEDs) are derived by dividing the total SED by a range of 10-12 SED per MED, representing the threshold for sunburn on fair skin. For comparative purposes, equivalent sunbathing time directly corresponds to the UVA exposure equivalent, while walking time equivalents are presented as a broader range, reflecting lower, more diffused exposure.

Sources

Evaluation of UV-A and UV-B transmission through the windows of gas, hybrid, and electric vehicles

DEFRA UV Index

Skin Cancer Foundation

UV Index in Barcelona, Spain