By Alexis Deaton EBS Staff Writer

Standing in the sunscreen aisle can be overwhelming. Since there are so many options, understanding the basics of sunscreen is essential to protecting yourself and your family.

Sun Protection Factor, or SPF, helps determine how long it takes before your skin starts to burn. To calculate this, multiply the SPF by the time it normally takes your skin to get red without protection. For example, if you start to burn in 15 minutes without any protection, using a sunscreen with SPF 30 will allow you to be in the sun for 450 minutes.

Does this mean going with the highest SPF is best? Not necessarily. SPF 100 is not twice as effective as SPF 50, and according to Consumer Report’s Sunscreen Buying Guide, it’s only an increase of 1 percent in actual protection – SPF 50 blocks 98 percent of UVB rays, while SPF 100 blocks 99 percent.

Also, keep in mind that SPF only refers to ultraviolet B (short-wave rays) blocking capabilities and not ultraviolet A (long-wave rays). Since the Food and Drug Administration does not believe you’ll receive additional protection from anything above SPF 50, your best bet is to stay between SPF 30 and 50.

By following a few basic steps – usually listed on sunscreen packaging – you can maximize the labeled SPF on the sunscreen. Apply at least two tablespoons for your entire body, and at least 15 minutes prior to sun exposure. Since sunscreen’s efficacy begins to diminish after an hour or two, reapply at least every two hours, and more often if you’re sweating or in the water.

What are the differences between UVA and UVB rays? Both types of rays can increase your risk of skin cancer, the most common form of cancer in the U.S. According to WebMD’s article titled “Sunscreen Safety,” UVA rays cause the most visible damage to your skin such as tanning and wrinkles. These are the rays we’re most exposed to since they can penetrate windows and clouds.

If you’ve ever been sunburned, UVB rays were responsible. UVBs are most intense from 10 a.m. to 4 p.m. during the spring and summer months, at high altitudes, and they also bounce off reflective surfaces.

Two categories of sunscreen ingredients are physical blockers, which scatter the sun’s rays, and chemical blockers, which react with the sun’s rays to prevent skin damage.

Common physical blockers are mineral-based ingredients such as titanium dioxide and zinc oxide – they can cause white streaking and may not have as an effective SPF as listed on the packaging. To prevent the white streaking, physical blockers that have been modified with nanoparticles are being used in some sunscreens. Studies have shown nanoparticles – after having made contact with water – are toxic to the various microorganisms in the environment, and may be small enough to penetrate our skin.

Common chemical blockers include oxybenzone and octinoxate one, and studies indicate they can be disruptive to our endocrine system. Most sunscreens with chemical blockers also have inactive ingredients, which are unnecessary and may be harmful.

But don’t let these concerns scare you away from using sunscreen. The benefits from any sunscreen above SPF 15 outweigh any potential harmful effects. A landmark study published in 2010 in the “Journal of Clinical Oncology” sampled 1,621 Australian adults and found 50 percent fewer melanomas – the most dangerous form of skin cancer – in those who had unlimited access to SPF 16 sunscreen.

The bottom line with sunscreen is to be knowledgeable about your options and stay simple: Stick with non-nanoparticle, mineral sunscreen lotions with SPF 30-50, with minimal inactive ingredients, and follow the label’s directions. Here’s to a skin-friendly, sun-filled summer.