an image from the US government EPA "Sunwise" program. I converted it from PDF format, and removed all the "sunwise" logos. the source link is here - http://www.epa.gov/sunwise/doc/guide.pdf
This is an illustration that I use originally for the new Creati Web Design website (http://creatiwebdesign.com), my own graphic company. But you also can use it for your works. Enjoy!