Sunscreen for Drivers: The Window Is the Problem

Your windshield is laminated glass and stops almost all UVA. Your side window is not, and on average it stops only 71 percent of it. That gap is why drivers age one side of the face faster than the other, with no sunburn to signal it, over years of ordinary shifts. If you drive for a living, the sunscreen that works is one that covers UVA, leaves your hands dry on the wheel, and does not sting when the cab gets hot. Swellies is five ingredients, zinc oxide as the only active, SPF 46, water resistant 40 minutes.

What the glass blocks, and what it doesn't

A 2016 study in JAMA Ophthalmology measured UVA blockage in 29 vehicles. The results split sharply by which window you are talking about.

• Windshields blocked 96 percent of UVA, in a tight range of 95 to 98 percent. Windshields are laminated, meaning a plastic layer bonded between two sheets of glass, and that layer does the work.
• Side windows blocked 71 percent on average, ranging from 96 percent down to 44 percent. Side glass is usually tempered, not laminated, so there is no plastic layer.
• Only 4 of the 29 vehicles blocked more than 90 percent at the side window. That is 14 percent of cars. The other 86 percent were letting a meaningful share through.

UVB is stopped by ordinary glass, which is why you do not burn through a car window. UVA is not, and UVA is the part that goes deeper and drives photoaging. You get the damage without the warning. The same mismatch applies in a cockpit, which we covered in sunscreen for pilots, and it is why UVA is worth understanding on its own terms in UVA is the real winter sun problem.

The most famous picture in dermatology

In 2012 the New England Journal of Medicine published a photograph of a 69-year-old man who had driven a delivery route for 28 years. The left side of his face, the side by the window, is thickened, furrowed and deeply lined. The right side looks like a different, younger man.

Same person. Same 28 years. Same genetics, diet and sleep. The only variable was which side sat next to the glass. No sunburn was ever involved, because the window had been filtering out the UVB the whole time.

Where it lands on a driver

• The window-side arm. In the US that is the left, since you sit on the left. In the UK, Australia and Japan the pattern flips to the right. The tan line stops at the sleeve and it is not even.
• The window-side face, ear and neck. Temple, cheek, the top of the ear, the side of the neck above the collar.
• The backs of your hands. They sit on the wheel in direct light for the entire shift, and hands show photoaging earlier than almost anywhere else.
• Everything, if you drive with the window down or work an open step van. Plenty of delivery routes are run with the bulkhead door open or no door at all, which means direct sun, not filtered sun, for eight or ten hours.

Why drivers skip sunscreen, and what fixes it

• It gets on the wheel. A greasy formula ends up on the wheel, the shifter and the clipboard. A gel that sets does not.
• It stings in a hot cab. Chemical filters and fragrance travel in sweat and end up in your eyes at the worst moment. Why that happens is in sunscreen that doesn't burn your eyes.
• It feels like a mask by the third hour. Thick mineral formulas sit on the face like paint. You notice it all day, then you stop putting it on.
• There is no good moment to reapply. There is, though: every stop is a moment. A pump in the door pocket takes twenty seconds at a loading dock.

Window film is the other half

Sunscreen handles your skin. Film handles the glass. A clear UV film on the side windows blocks most of the UVA without darkening the window, which matters because tint darkness is regulated and the limits vary by state. Clear UV-blocking film generally passes those limits where dark tint does not. If you spend a career in a cab, it is the cheapest permanent fix you can make, and it protects the arm and shoulder that sunscreen gets forgotten on.

Where Swellies fits

Five ingredients. Non-nano zinc oxide at 21 percent as the only active, covering UVA and UVB on its own, which is the point when the glass is already handling UVB and leaving the UVA to you. Iron oxides add a sheer tint and filter visible light.

• It sets instead of sitting slick, so your grip on the wheel stays your grip on the wheel.
• No fragrance, no chemical filters, no water, which are the three things that run into your eyes when the cab heats up.
• Lightweight enough to forget, which is what decides whether you are still wearing it in month three.
• SPF 46, water resistant 40 minutes, in a 50ml airless pump that lives in a door pocket and doses the same amount every press.

Frequently asked questions

Do car windows block UV rays?

Partly. Windshields are laminated and block about 96 percent of UVA. Side windows are usually tempered glass and block about 71 percent on average, with some as low as 44 percent. Ordinary glass stops nearly all UVB, which is why you do not get sunburned through a window even though UVA is still reaching you.

Do truck drivers need sunscreen?

Yes, and the reason is the side window rather than the windshield. Long shifts next to glass that passes UVA produce one-sided photoaging on the arm, face, ear and neck. The New England Journal of Medicine published a widely cited photograph in 2012 of a driver whose left side showed 28 years of it while his right side did not.

What causes trucker arm?

UVA through the driver's side window. It passes through tempered glass while UVB is blocked, so the arm nearest the window accumulates sun exposure for years without burning. In the US it shows on the left arm. In right-hand-drive countries it shows on the right.

What is the best sunscreen for delivery drivers?

A mineral sunscreen with zinc oxide as the only active, since zinc covers deep into UVA, in a texture that sets rather than staying greasy on your hands, with nothing in it that runs into your eyes when the cab gets hot. Swellies is five ingredients, 21 percent non-nano zinc oxide, SPF 46, fragrance-free, water resistant 40 minutes, in a 50ml pump.

Does window tint protect you from UV?

Clear UV-blocking film blocks most UVA without darkening the glass, which keeps it within the tint limits that vary by state. Darkness and UV protection are separate properties, so a dark window is not automatically a protective one, and a clear film can be.

How often should a driver reapply sunscreen?

About every two hours of exposure, and after heavy sweating. Stops are the natural moment for it. A pump kept in the door pocket makes the reapplication realistic, which a tube at home does not.

Five ingredients. Nothing on your hands, nothing in your eyes, nothing you notice at hour six. Shop Swellies SPF 46 →