Ultraviolet radiation damages skin DNA and accelerates premature aging and wrinkles. Sunscreen reduces these effects by blocking UV light, absorbing it, or both. Mineral or physical formulations using zinc oxide and titanium dioxide reflect UV radiation and can also absorb UV light, acting like nanoparticle-size mirrors and often appearing pasty white. Chemical formulations use molecules that absorb different UV wavelengths and convert the absorbed energy into heat, typically appearing more transparent and leaving less visible residue. Formulation differences, including texture and application form, can make sunscreen confusing, and SPF level selection remains an important practical consideration for effective protection.
"Sunscreen typically protects our skin from those harmful rays in two ways: by blocking UV light or by absorbing it (or both). Mineral or physical sunscreens—formulations made with zinc oxide and titanium dioxide—are thought to be UV blockers, although research shows they can also absorb UV light, too. They act as nanoparticle-size mirrors to reflect UV radiation and visible light, says David Fisher, a professor in the department of Dermatology at Harvard Medical School and a physician at Massachusetts General Hospital. That's also why they tend to be pasty white in color."
"Chemical sunscreens are primarily UV absorbers. Chemical sunscreens are essentially utilizing molecules that can absorb different wavelengths within the UV portion of the spectrum, Fisher explains. Then they convert the UV light into heat. These sunscreens are typically transparent, and don't leave a white sheen on the skin, says Kerry Hanson, a research"
Read at www.scientificamerican.com
Unable to calculate read time
Collection
[
|
...
]