With temperatures reaching 90 degrees in Los Angeles, avoiding the heat wasn’t exactly an option while at a family member’s outdoor party in August. So I sat under an umbrella with a powerful fan nearby, thinking I was protected from the sun and heat. Half an hour later, I felt exhausted, dizzy, nauseous, and generally unwell—symptoms consistent with heat exhaustion.
Around the same time, I received a notification from an app used by the $249 ($149 at press time) UV tracking collar I had been using, called Gem, from a company called The90. He noticed that my UV exposure had increased considerably. It turns out that this patio umbrella does not repel ultraviolet radiation and it is difficult to be completely protected because the radiation can be reflected or scattered by objects in the environment. While UV exposure and overheating are different things, I wrongly assumed that shade and a fan would adequately protect me from both.
This led me to a discovery: one of my medications increases my sensitivity to heat, which helped explain similar episodes I had experienced over the years. The Gem didn’t diagnose anything, but it prompted me to investigate something I would have otherwise dismissed. Since then, I’ve been more conscious about limiting my time outdoors during peak heat and UV rays, staying hydrated, and paying more attention to how I feel outside.
I admit that my initial interest in UV tracking was largely driven by vanity. As much as I try to challenge harmful beauty standards, I’m not immune to them. Having started graying in my 20s, I am interested in slowing down other visible signs of aging where reasonably possible. But between being Indian (I rarely get sunburned thanks in part to my skin’s higher melanin content, although that doesn’t eliminate the risk of sun damage or skin cancer) and living within walking distance of the beach in always sunny Los Angeles, I hadn’t given much thought to how much UV exposure I was actually getting. The Gem has helped me understand it better by providing a variety of estimates, some more useful than others.
The included UV detection sensor measures UVA and UVB radiation separately, rather than simply displaying the UV forecast for my area. UVB rays are primarily responsible for sunburn and help the skin produce vitamin D, while UVA rays contribute to premature aging, even when you don’t visibly burn. Fortunately, getting these metrics doesn’t come with the cost of using a bulky device. The circle pendant comes with a nice thin necklace that I would happily wear even if it didn’t track anything. Its titanium, gold or silver chain pairs well with a variety of outfits. Battery life lasted almost exactly a week (the advertised lifespan) and the Gem recharges using an included charging base. The90 plans to release a hat clip and bag tag early next year, which seem ideal for those who prefer not to wear them around their neck.
The mobile app is essential to the experience. It has easy-to-read graphics and simple explanations. I enjoyed using it. While not necessary, you can create a skin profile so you can estimate a variety of metrics based on the sensor’s UVA and UVB readings. The profile is based on factors such as skin type, sensitivity, clothing and sunscreen. That means their estimates are not based solely on UV exposure, although they are still predictions rather than direct measurements of how your body responds to sunlight.
there is a batch here, including your estimated vitamin D production, potential circadian light benefits, estimated nitric oxide-related benefits, cumulative UVA exposure, and recent cumulative UVA exposure. In addition to cumulative UVA exposure and weekly trends, its Skin Aging Zone assesses potential aging-related risks and offers personalized skin care advice. It also provides a personalized sunburn countdown, sun protection reminders, and a daily sun score.
Sun Score is a rating that incorporates several metrics to balance the potential benefits of sunlight with the risks of overexposure. The company encourages users to aim for a daily sun score of 90, although more sun is not necessarily better. Too little exposure means missing out on potential benefits, while excessive UV rays can damage the skin. I appreciated the context, but the individual estimated measurements were more revealing than the Sun Score.
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The UV readings in the app responded quickly as I moved between sunlight, shade, and indoors, even recording changes near windows. I couldn’t independently verify the sensor’s accuracy, but the readings behaved as expected when changing environments. However, there were times when I noticed that the Gem sometimes didn’t register that I had been outside. Finally, I discovered that the app must remain running in the background (at least on iPhone; I haven’t tested it on Android), since the measurements are not stored on the sensor and closing the app completely breaks the tracking.
My experience at the outdoor party challenged my assumptions about how much protection I was getting from the shade. Equally surprising to me was discovering how few UVB rays I accumulated during a typical week, despite living in such a sunny location. I didn’t meet the estimated target for sunlight-derived vitamin D from the app almost daily, which led me to investigate how melanin, while offering some natural protection against UV rays, affects vitamin D production from sunlight. Until then, I mainly thought about sun exposure in terms of protecting my skin from damage. Seeing how few UVB rays I was accumulating made me consider what I might be losing too.
The vitamin D countdown was not as helpful as I had hoped. During one test, his estimate of how much additional sunlight he needed dropped from several hours to less than an hour, then rose to more than six hours just a few minutes later. The fluctuations seemed to be related to the changing intensity of UVB rays, although I couldn’t verify this. I noticed similar fluctuations in the app’s estimated time to sunburn. With both countdowns changing so dramatically, I stopped paying close attention to the exact times and focused on the bigger picture: whether I felt like I was getting too much or too little sun.
That was perhaps the biggest surprise when testing the Gem. After my experience using it at the garden party in August, I was hoping it would encourage me to spend less time in the sun each day. In reality, my exposure often falls into one of two extremes: too little to meet the app’s estimated goals or enough to raise concerns about overexposure, even when I thought I was protected by the shade.
Now I try to be more aware of my UV exposure, even when I’m not wearing Gem. I try to limit the time I spend outdoors during peak UV hours and try to get some sunlight on days I spend mostly indoors. I credit Gem for helping me better understand how my time outdoors could affect my well-being in ways I had never considered, although the usefulness of her findings may vary.
At $249 off sale, it’s pricey, although it’s nice that it doesn’t have a subscription. Personally, I can’t justify the price given how much time I spend indoors, but I see the appeal for people who spend considerable time outdoors or for those who want to be more conscious about sun protection. For the price, I wish the app’s guidance was clearer at times and I wish it could track UV rays without the app being open in the background, but ultimately Gem made me think less about what my body looks like and more about how I’m treating it. he.
Photography by Sheena Vasani / The Verge
