Photoaging is mostly caused by incidental sun exposure

Love the sun? Hate the sun? Whatever you do, you have to respect the sun. This means being mindful of incidental sun exposure throughout your day. Incidental, or unexpected, non intentional and sporadic exposure to the sun accounts for about 80% of our total sun exposure, and it’s responsible for most of our photoaging that occurs.
Our skin catches harmful ultraviolets when we least expect it. Commuting to work? We’re exposed! Running errands? We’re exposed! Even sitting at our desk near a window, we’re exposed to skin-damaging rays.
On days when the sky is cloudy, or a snowstorm is brewing, don’t be fooled into thinking you’re safe. Harmful rays penetrate through all manner of clouds and snow.
So keep this in mind, and realize that 10 minutes here, or 20 minutes there, really adds up throughout the day. And this incidental exposure is not doing your skin any favors.