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Spray Vs Lotion V3.0


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Spray Vs Lotion V3.0

  1. 1. Spray Vs. Lotion: The Effect of Sunblock on UVA and UVB F. Allaire, A. Suenobu, L. Wells PHYS 399 Summer ’09
  2. 2. Ultraviolet Radiation  Ultraviolet (UV) ultraviolet light is the light just past the wavelength of the color violet on the electromagnetic spectrum  UVA frequency ranges 400 - 320 nm  UVB frequency ranges 320 - 290 nm  UVC frequency ranges 290 - 100 nm (these waves are absorbed completely by oxygen and the ozone layer)
  3. 3. UVA –responsible for suntans and premature aging of the skin and some cancers UVB associated with sunburns, cataracts and skin cancer
  4. 4. Why should we care about UVA or UVB radiation?  Premature aging of the skin  Damaging the skin’s cellular DNA  Various forms of skin cancer  Eye damage including cataracts  Reddening of the skin and sunburn
  5. 5. Protective measures  Wear clothing with  Use sunglasses  Seek shade  Wear hats  SPF - Sun Protection Factor The Skin Cancer Foundation maintains that SPF’s of 15 or higher are necessary for adequate protection.
  6. 6. Purpose  We know that sunscreen does protect. The purpose of this experiment is to determine if there is a difference in effectiveness of protection from UVA and UVB radiation between lotion or clear spray-on sunblock.
  7. 7. Hypothesis  We predict that the lotion would provide more protection than a clear spray-on sunblock of the same SPF value.
  8. 8. Experimental Design  Independent variable: Lotion / Spray- on Sunblock  Dependent variable: UVA, UVB penetration (mW/m2)  Constants: Time of day, amount of sunblock, length of time, SPF, brand, multiple trials using same procedure for each trial,  Control: Clear plastic –no sunblock
  9. 9. Experimental Design Lotion Control Spray
  10. 10. Experimental Design UVA and UVB Probes and the LabQuest handheld device.
  11. 11. The application of sunblock Lotion Spray
  12. 12. Setting up in the sun….
  13. 13. Data collection:  Day 1 – Ran 3 trials beginning at 9:55 am until completed.  Day 2 - Ran 3 trails beginning at 10:30 am until completed.  Averages were then made using all 6 trials for the 2 days the experiment was conducted.  We worked carefully to keep all other variables to a minimum.
  14. 14. Variables that could affect results… Cloudy day!
  15. 15. Variables that could affect results… The amount of spray: Two pumps of the spray bottle from the same distance away from plastic!!
  16. 16. Variables that could affect results… The amount of lotion: Small amount each time on fingertips applied with the same pressure onto plastic.
  17. 17. UVA: Comparing spray, lotion and control
  18. 18. UVA: Comparing spray and lotion
  19. 19. UVB: Comparing spray, lotion and control
  20. 20. UVB: Comparing spray, lotion and control
  21. 21. Now for some numbers… UVA UVB Sunblock Irradiance % Total Irradiance % Total (mW/m2) (mW/m2) Control 7181.645 100 341.9 100 Lotion 159.673 0.022 13.8 0.040 Spray 272.284 0.038 13.3 0.039
  22. 22. Conclusions  Our hypothesis was refuted  Difference between spray/lotion and control is significant  Difference between spray and lotion seems insignificant  Wear something!
  23. 23. Extensions  Compare brands that have same SPF value  Compare various SPF values  Compare time after application  Sunblock vs. SPF clothing/sun glasses  Effectiveness after water immersion  Amount of lotion/spray applied  Price vs. effectiveness
  24. 24. Student Research  Informal survey: How many students wear sunblock?  Data from this experiment can be used as a demo to introduce the topic.  Students will design and conduct experiments based on extensions provided in the conclusion.