When it comes to packing for trips, most people have the basics covered. But there’s one item – no matter the length of flight, climate at the destination, and time of year – that has a tendency to slip through the cracks: sunscreen. But why is this a travel essential? While many forgo sunblock on grey days or in the fall and winter, that’s a huge mistake because the sun’s ultraviolet rays (UVA and UVB) are present every day of the year, in every weather condition – yes, even on overcast days. (According to Dr. Patricia Wexler of Wexler Dermatology, a whopping 80% of the sun’s UV rays can pass through the clouds.) What’s the difference between the two? “UVB rays can cause sunburn, and their intensity varies from summer to winter,” explains Wexler. “But, UVA rays penetrate deeper into your skin, and can cause skin aging and skin cancer.” And if you think being in a plane means you’re safe from the sun’s damaging rays, think again. Higher elevations, especially when you’re in a window seat above the clouds – they absorb at least a bit of UV radiation when you’re on the ground – translates into direct, unfiltered exposure. “Almost all forms of skin cancer are associated with ...