Warm weather is back again, and with it comes longer days, and more time in the sun. In an attempt to stave off painful sunburns and lower your risk of skin cancer, you're likely to be applying sunscreen before you embark on your outdoor endeavors. But the type of sunscreen you're using and how you're applying it plays a big role in how effective it is, and whether it's actually damaging your body each time you use it.

First let’s talk about the types of sunscreens available. There are two main types: chemical sunscreens and mineral sunscreens. If you look at the “Active Ingredient” panel on the back of your sunscreen and see oxybenzone, homosalate, octinoxate or other ingredients you can’t pronounce, you have a chemical sunscreen. Chemical sunscreens can be problematic for a number of different reasons. These ingredients are able to pass through our skin into our bloodstream where they act as endocrine disruptors. Endocrine disruptors are substances that cause our own hormone feedback loops to scramble and can cause imbalance in our estrogen and thyroid hormones. Chemical sunscreens have also been shown to cause free radical damage. The very reason we use sunscreen in the first place is to protect our skin from free radical damage from the sun, yet these sunscreens actually cause this damage! It's important to note that the United States and Australia are the heaviest users of sunscreen, yet these two countries also have the highest incidence of skin cancer.

A safer alternative to chemical sunscreens are mineral sunscreens. Mineral sunscreens contain titanium dioxide and/or zinc oxide as their active ingredients. These products do not filter into the blood stream and cause the same free radical or hormone issues that we see with chemical sunscreens. However, there is potential danger here too. Some of the "semi-natural" sunscreens are using Nano-particle ingredients that go deep into the tissues and create significant health risks. So as you're reading the labels, be sure to look for a statement that says something like, "No Nano-Particles", or "Does Not Contain Nano-Particle Ingredients".

Regardless of the type of sunscreen you choose to use, it's absolutely critical that it is applied properly. ALL sunscreens should be reapplied every two hours, more frequently if swimming or sweating regardless if the bottle says it’s waterproof. Sunscreens need to be applied generously in order to be effective - a full ounce (about a shot glass worth) is needed to cover all limbs and your face. Many people mistakenly believe that if they are using a sunscreen with a higher SPF they are getting significantly more coverage, therefore they do not need to reapply as frequently or generously. Not so. A sunscreen with SPF 15, when applied properly, will protect from 93% of the sun’s UVB rays. An SPF of 30, when applied properly, will protect from 97% of the sun’s rays - a mere 4% more protection.

A final thought to keep in mind. There are two types of rays emitted by the sun - UVA and UVB. UVB rays are the ones that are responsible for making vitamin D and giving us sunburns. UVA rays, however, actually penetrate deeper into the skin and are the primary cause of skin cancer, wrinkles and sunspots. The SPF rating on a bottle of sunscreen is only specifying how much of the sun’s UVB rays are getting blocked. This rating system does not tell us if or how much of the arguably more harmful UVA rays are getting blocked. If we choose a sunscreen that specifies that it offers “broad spectrum” protection we can be assured that we are getting at least some UVA protection. In general, mineral sunscreens are more effective at blocking UVA rays than chemical sunscreens.

Does all of this sound like more information than you want to think about? If so, consider simply being conscientious about the time of day you receive sun exposure, and the type of clothing you are wearing. The sun’s UVB rays are the most intense between 10am and 4pm, so it may be wise to stay indoors or in the shade during this time. If you want to maximize vitamin D synthesis, expose torso, back and limbs until your skin turns a very light pink (read: Do not get even slightly sunburned!). Then cover up with light clothing. Garments with a UPF rating offer an additional layer of protection for those who are sun-sensitive.

To sum it up, make sure you enjoy the summer sun safely by choosing mineral sunscreens over chemical, use a shot glass worth for each application and reapply at least every two hours. Keep in mind that the time of day you are in the sun and how many of your parts are exposed may be the most critical factor for protecting your skin. And if you do get a sunburn, know that apple cider vinegar will take the heat out immediately. Have fun and love the sun!