You may have heard that: “SPF 30 absorbs 97% of the UV” or “SPF 50 absorbs 98% of the UV”. These numbers are from a math model and it’s quite simple! The math model is: 1 – (1 ÷ SPF) 1 divided by the sunscreen’s SPF, subtracted from 1. With an SPF 30: 1 – […]
Sunscreens and moisturizers with SPF are tested at a standardized density. That density is 2 milligrams of sunscreen per square centimeter of skin. If we want protection closer to what’s on the label, we should be using sunscreen or moisturizers with SPF at the density they’re tested at too. Most of us don’t know the […]
What happens to your sunscreen throughout a work day? I often get this question, especially from people who work inside for most of the day. A group of researchers at Mahidol University in Thailand did an experiment that may provide us with some guidance. The researchers took 20 people (15 women) with mostly skin phototype […]
Cyclobutane pyrimidine dimers (CPDs) are a form of DNA damage that is caused by UV exposure. CPDs interfere with base pairing during DNA replication – which can lead to mutations and cancer. UVB radiation is directly absorbed by DNA. The energy causes changes in the bonding of pyrimidine structures found in DNA leading to CPDs […]
I’ve received quite a few questions about the organic sunscreen chemical Avobenzone over the years and I wanted to shed some light on one of the most common concerns – its photodegradation in UV. These concerns are usually raised by websites that say things like, “Avobenzone degrades in the sun, resulting in the release of free […]
Optical coherence tomography and reflectance confocal microscopy can be used to non-invasively to visualize deep into the skin. Using these techniques we can actually see changes in the structure of the skin and its cells. This group of researchers with funding from La Roche Posay used the imaging techniques to compare the effect of UVB […]
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