With Memorial Day marking the unofficial start of summer, many mature women start thinking about increasing the sun protection they use. But how much do you really need? Should you up your SPF from 30 to 100 during hot summer months?

Not necessarily, say experts.

False sense of protection. While SPF 30 sunscreen blocks 97 percent of sunburn rays, SPF 100 blocks 99 percent, a mere two percent difference. But here’s the thing: Higher SPFs give people a false sense of security, leading them to apply less than the recommended amount (about a shot glass for your entire body). If you apply only 25 percent of the recommended amount of SPF 30 sunscreen, the sunburn protection on the skin is actually only 2.3. And if you apply SPF 100 sparingly, you can end up with a functional SPF as low as 3.2, which is less effective than a T-shirt, which usually has an SPF of 5! Scary, isn’t it? So a liberally applied SPF 15 is better than SPF 100 applied sparingly.

Chemical overload. High SPF sunscreens naturally have higher concentrations of sun-filtering chemicals than low SPF sunscreens. When they penetrate the skin, some of these ingredients may pose health risks, including tissue damage, hormone disruption or allergic skin reactions. Because higher SPF sunscreens haven’t been proven to reduce the risk of skin cancer and sun damage, those extra chemicals cause more harm than good.

So what should you do? First, choosing sunscreens with lower concentrations of active ingredients – SPF 30 instead of SPF 100 – is smart. Then, make sure to apply liberally all over your body (even your ears, which is an often forgotten part when it comes to sun protection). And reapply throughout the day, especially if you’re been in the water or washing your hands excessively. If you’re sensitive to most sunscreens, try physical sunscreens made with active mineral ingredients, such as titanium dioxide or zinc oxide, which work by sitting on top of the skin to deflect damaging UV rays away from the skin.