This past weekend, we looked at the sunscreen regulatory drama playing out in the US Congress and in the US Food and Drug Administration (FDA) over what types of sunscreens should be allowed to be sold in America. Other countries have more modern sunscreens that last longer and block more UV rays from reaching our skin, while those sold here tend to be more greasy and sticky.
But while all of that is being worked out, we Utahs still need to protect ourselves.
Utah has it The highest rate of melanoma in the United States, according to the Centers for Disease Control and Prevention. Nationally, about 20 people in 100,000 are diagnosed with skin cancer each year; In Utah, that number is about 40 per 100,000. It’s easy to explain: we’re outside more often than the average state, and we’re also fairer-skinned than the rest of the states.
So using sunscreen correctly is more important here than anywhere else. Unfortunately, studies show that people everywhere are pretty bad at applying sunscreen the right way.
You are familiar with the sun protection factor (SPF), right? This is the sun protection factor, which basically measures how much sunlight passes through the sunscreen. If a sunscreen has an SPF of 30, that means that one out of every 30 rays gets through. Experts calculate this in terms of time, let’s say it takes one minute for a section of skin to turn red without sunscreen. If it takes 30 minutes for it to turn red with sunscreen on, that sun protection factor is SPF 30.
But here’s the catch: In these tests, sunscreen is applied to human skin at a rate of 2 milligrams per square centimeter. In fact, people use half or a quarter of it.
a lot of Various studies That result appears. My favorite was the study of nudist beachgoers, in which they weighed the sunscreen bottles of 42 men, women, and children before and after applying full-body sunscreen. The researchers found that people used 0.5 milligrams per square centimeter, not 2. Another study of people who were on vacation for one week in Egypt found that men used 0.93 mg/cm², while women used 0.66 mg/cm².
The researchers were curious to see if method of application mattered, and had different classes of children use different sunscreen – if the kids applied sunscreen, they got 0.22 mg/cm2 on themselves, and those with a squeeze bottle used 0.57 mg. / cm2, and those with a squeeze bottle used 0.57 mg / cm2. The pump bottle used 0.75 mg / cm2. Regardless, people don’t use enough sunscreen.
Even if you tell people they don’t use enough sunscreen, they still don’t use enough sunscreen. One study taught people how to use sunscreen – “Hey, you need to use 2mg/cm². Here’s how much sunscreen there is, here’s how to apply it, etc. They raised their application levels to just 1.13 mg/cm².
The problem is that seems likely That SPF and thickness of application have an exponential relationship. In other words, if you use half the amount of sunscreen you should be using, you’ll only get the square root of SPF. Using real-world numbers: If your application thickness is 1 mg/cm², then SPF 30 sunscreen converts to SPF 5 sunscreen. If your application thickness is 0.5 mg/cm², SPF 30 sunscreen converts to Sunscreen with SPF 2.
As a result, every study I’ve been able to find has come to an interesting conclusion: There is a connection between sunscreen use more sunstroke. People feel more confident going out in the sun thanks to their sunscreen, even if it’s spotty or light.
So what can you do to make sure you don’t fall into this trap? Different dermatologists recommend different tricks. Here are what resonates with me the most:
• If you do the math on 2 mg/cm², that means an average sized human should use about 1 fluid ounce. ounce. of sunscreen every time they apply sunscreen. Increase the amount if you have a larger surface area than the average human’s skin. One fluid ounce is about a cup of sunscreen. Knowing this is also helpful if you’re calculating how much sunscreen to bring with you on a trip.
• How do you make sure you get that much sunscreen everywhere? One Fun paper Suggest teaching dermatologist visitors about the “rule of nines” — 11 areas of your body that each make up about 9% of your total skin. Those 11 areas: your head, neck, and face; left arm; right hand; upper back; lower back; upper chest; Below the stomach is the upper part of the left leg. The upper part of the right leg. lower left leg and foot. Lower right leg and foot.
Each of these has to have their own application of two “fingers” of sunscreen—basically, take out two fingers and squeeze a line of sunscreen from the palm to the fingertip on each finger.
• Because we know people don’t typically use 2 mg/cm² in one application, many dermatologists recommend applying sunscreen twice, usually 15 to 30 minutes apart, to get the full dose needed.
• Spray sunscreen can be just as effective as sunscreen, but most people get it wrong. It is necessary to rub in sunscreen. Do not use if there is a slight wind, as the majority of the aerosol will fly away. Honestly, it’s probably the most effective thing to just squirt sunscreen into your hand, and then rub it into your skin afterwards.
• This is partly because older, less effective sunscreen filters are available in the US and will need to be reapplied more frequently, at least every two hours. If you’re swimming or sweating, every hour is probably more like that.
• Especially here in our altitude state of Utah, putting on the right sunscreen is a year-round business. Check the UV Index on fall and winter days too, when you’re heading outside for a hike or a day skiing.
• Honestly, just because you wear sunscreen doesn’t mean you can’t use other sun protection tools. wear a hat! Find some shade! Take breaks indoors! Multiple protections used simultaneously will be more effective.
Andy Larsen Data columnist for The Salt Lake Tribune. You can access it at email@example.com
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