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The sun is out! On Friday I got soaked in the rain at BioBlitz, and on Saturday I got baked in the sun at the Illinois Institute of Technology's 2009 Graduation.
Between the hours of 9am and 2pm, I sat in a white folding chair listening to Pomp and Circumstance watching the next generation of engineers in their black gowns and hats get their diplomas. The sun made me feel warm and happy, but its ultraviolet (UV) light, invisible, was causing significant skin damage. Sunlight hits the earth in three forms: infrared (heat), visible, and UV light. UV light can be categorized based on their wavelengths in nanometers into UV-A (400 to 320 nm) which is not absorbed by the ozone layer and is the least harmful radiation, UV-B (320 to 290nm) which is absorbed partially by the ozone layer, and UV-C (100 to 290nm) which is completely absorbed by the ozone layer. UV-A causes tans, UV-B causes sunburns, and UV-C almost never reaches us. The UV-A and UV-B light from the sun killed some of my skin cells and damaged my DNA.
After a graduation day in the sun, I came home hurting with red splotchy sunburn (that's right Dr. Rabiah I was NOT wearing sunscreen). My body responded to my skin's cellular damage by increasing the blood flow to my capillary bed of the dermis in order to bring in cells to repair the damage. The extra blood in my capillaries caused my skin to turn all rosy. When I pressed on my sunburned skin it turned white, and then returned to red as my capillaries refilled. Unfortunately, this extra blood also made my skin itchy and hot. Itching like crazy, I popped an aspirin immediately, drank water, took a cold bath, and slathered Aloe Vera all over.
On Sunday (after a tossing and turning sleep), I ran (run I did) to the drug store to get some sunscreen to avoid this sunburned aftermath in the future. Standing in front of Coppertone, Banana Boat, and Neutrogena of Sun Protection Factors (SPF) 2, 15, 30, 50, however, I was totally confused. What exactly is sunscreen, and how does it work? Sunscreens (most of them) protect against UV-B radiation, and they work by chemically absorbing some of these UV-B rays. The SPF number (only applicable to UV-B radiation) tells you how long you have before you burn, so wearing SPF 2 lets you stay in the sun twice as long as without. Theoretically, if it takes 15 minutes for you to beginning reddening, using SPF 15 sunscreen prevents reddening approximately 15 times longer, or about 3.75 hours; however, make sure to continually reapply for maximum results. In panic mode, I bought the more expensive SPF 50. Most importantly, everyone should wear sunscreen (even in the winter and especially in the summer) because exposure to UV-B rays damages your DNA, and unrepaired genetic damage can lead to skin cancer. So as the Australians say, slip, slop, slap: slip on a shirt, slop on some sunscreen, and slap on a hat.
So Ladies and Gentleman of the Class of 2009 (and everyone else too): Wear Sunscreen!
Baz Luhrmann - Everybody's Free (To Wear Sunscreen)
-Heather
Author's Note: This was submitted to the blog by Heather, one of our corespondents.
Sources:
http://blogs.nationalgeographic.com/blogs/bioblitz/indiana-dunes-ntl-lakeshore-bi/
http://www.iit.edu/
http://www.youtube.com/watch?v=gxqFdcZz974
http://science.hq.nasa.gov/kids/imagers/ems/infrared.html
http://science.hq.nasa.gov/kids/imagers/ems/visible.html
http://science.hq.nasa.gov/kids/imagers/ems/uv.html
http://en.wikipedia.org/wiki/Wavelength
http://www.nas.nasa.gov/About/Education/Ozone/ozonelayer.html
http://www.mayoclinic.com/health/sunburn/DS00964
http://www.mayoclinic.com/health/sunscreen/SN00044
http://en.wikipedia.org/wiki/Capillaries
http://www.medterms.com/script/main/art.asp?articlekey=2958
http://www.coppertone.com/coppertone/index.jsp
http://www.bananaboat.com/
http://www.neutrogena.com/econsumer/ntg/index.view
http://www.fda.gov/cder/offices/OTC/understanding_spf_sunscreen.htm
http://www.kidzworld.com/article/1014-too-hot-to-handle-the-sunburn-reality
http://www.youtube.com/watch?v=RFjsRtPvoaM
Editor's Note: For more blogs from Dr. Rabiah, visit Science Chicago's website at: http://www.sciencechicagoblog.com
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