People around the globe have protected their skin using a variety of substances throughout history. In the 19th and 20th centuries, deeper understanding of sunlight and the way it affects skin led to more protective sunscreen formulations. 

Research:

• Aldahan AS, Shah VV, Mlacker S, Nouri K. “The History of Sunscreen.” JAMA Dermatol. 2015;151(12):1316. doi:10.1001/jamadermatol.2015.3011
• Belmont, Trixie. “Suntans With Pay Off.” The Baltimore Sun. June 13, 1967. https://www.newspapers.com/image/377122417/?terms=%22franz%20greiter%22%20&match=1
• Britannica, The Editors of Encyclopaedia. "Johann Wilhelm Ritter". Encyclopedia Britannica, 19 Jan. 2023, https://www.britannica.com/biography/Johann-Wilhelm-Ritter
• Diffey, B. “Has the sun protection factor had its day?.” BMJ (Clinical research ed.) 320,7228 (2000): 176-7. doi:10.1136/bmj.320.7228.176
• Greiter, F. and Gschnait, F. “EFFECT OF UV LIGHT ON HUMANS.” Photochemistry and Photobiology. 1984. 39: 869-873. https://doi.org/10.1111/j.1751-1097.1984.tb08873.x
• Hodgskiss, Tammy. “What the use of ochre tells us about the capabilities of our African ancestry.” The Conversation. Sept. 7, 2015. https://theconversation.com/what-the-use-of-ochre-tells-us-about-the-capabilities-of-our-african-ancestry-47081
• “History of Hamilton.” https://www.hamiltonsunandskin.com.au/history-of-hamilton
• Leach, Doreen, and Julie Beckwith. “The founders of dermatology: Robert WilIan and Thomas Bateman.” Journal of the Royal College of Physicians of London. Vol. 33, No. 6. November/December 1999. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9665792/pdf/jrcollphyslond146949-0084.pdf
• MacEACHERN W.N. and O.F. JILLSON. “A Practical Sunscreen— ‘Red Vet Pet.’” Arch Dermatol. 1964;89(1):147–150. doi:10.1001/archderm.1964.01590250153027
• Rathish, Shruthi, and Sebastian Criton. “Robert Willan – A True Pioneer.”  Department of Dermatology, Venereology and Leprosy, Amala Institute of Medical Sciences, Thrissur, Kerala,  April 22, 2019. https://jsstd.org/robert-willan-a-true-pioneer/
• Rubin, Penny. “Only on Sun Days.” The Province. January 4, 1975. https://www.newspapers.com/image/501299818/?terms=%22franz%20greiter%22&match=1
• “The science of sunscreen.” Harvard Health Publishing.  Feb 15, 2021. https://www.health.harvard.edu/staying-healthy/the-science-of-sunscreen
• Skin Cancer Foundation. “Ask the Expert: Does a High SPF Protect My Skin Better?”May 1. 2023. https://www.skincancer.org/blog/ask-the-expert-does-a-high-spf-protect-my-skin-better/
• “Sunscreen: How to Help Protect Your Skin from the Sun.” FDA. https://www.fda.gov/drugs/understanding-over-counter-medicines/sunscreen-how-help-protect-your-skin-sun#spf
• “SUNSCREEN IN THE ENVIRONMENT:The History of Sunscreen's Effect on Corals.” Smithsonian Institute Oceans. https://ocean.si.edu/ecosystems/coral-reefs/sunscreen-environment
• “Sun Tan Free, by the Inch.” The San Francisco Examiner. June 18, 1967. https://www.newspapers.com/image/458648765/?terms=%22franz%20greiter%22&match=1
• Svarc, Federico. "A brief illustrated history on sunscreens and sun protection" Pure and Applied Chemistry, vol. 87, no. 9-10, 2015, pp. 929-936. https://doi.org/10.1515/pac-2015-0303
• Urbach, Frederick. “The historical aspects of sunscreens.” Journal of Photochemistry and Photobiology B: Biology. Volume 64, Issues 2–3. 2001.Pages 99-104. https://doi.org/10.1016/S1011-1344(01)00202-0.
• Urbach, F. “Franz Greiter – The Man and His Work.” Photobiology. 1991. https://doi.org/10.1007/978-1-4615-3732-8_82