Sunscreen is a must for anyone who spends time outside. Your bottle probably mentions something about UVA and UVB rays. Since you care so much about your health, I thought I'd refresh your mind on the difference between the two.
UVA rays: These are less likely to cause sunburn than UVB rays, but they penetrate your skin more deeply. Watch out because UVA rays can go through windows, lightweight clothing, and even your car windshield. Prolonged exposure cracks and shrinks the collagen and elastin in your skin, which is why UVA rays are responsible for signs of aging including wrinkles, saggy and leathery skin, and suns spots.
UVB rays: These are responsible for tanning your skin, but they also cause sunburn. UVB rays are the main culprit when it comes to skin cancer. These rays also go through windows, and it doesn't matter if it's cloudy — you're still at risk for exposure.
Although both types are responsible for different health risks, they're equally harmful to your skin. So if you're planning on enjoying the day outdoors, lube up with a sunscreen that protects against both UVA and UVB rays 20 to 30 minutes before heading out. Reapply at least every two hours.