Your windshield doesn't block all UV.

Yes, you should wear sunscreen while driving. The glass in your windshield blocks most UVB rays, but UVA rays (the ones that cause aging and skin cancer) go right through it. Side and rear windows are even worse — they’re usually not treated to block UVA at all.

So if you commute, run errands, or just sit in traffic, that arm and that side of your face are getting a steady dose of radiation you can’t see or feel. It adds up over years. You don’t notice it until the dermatologist does.

Just grab a daily moisturizer with SPF 30 or higher and put it on before you leave the house. It takes ten seconds.