Excellence in beauty, electrolysis, aromatherapy, reflexology, massage, St Tropez and Guinot in Effingham and East/West Horsley

Frances O'Reilly

SKIN CARE THERAPIST and HOLISTIC THERAPIST
MBABTAC dip CIBTAC ITEC ICA IEB C&G

'Coppertrees'
Forest Road
Effingham / East Horsley
Surrey
KT24 5HE

Tel: 01483 281632
Coppertrees is now open for business. For more details see my Covid 19 page

Sun Protection Factors

Question

What is the difference between SPF15 and SPF30? Is it double the protection?

Answer

An SPF30 does not provide double the protection. The difference is only in time. To demonstrate this difference, see chart below:

For example, if your skin starts to burn in 10 minutes without any sun protection an SPF15 gives you 15x10 or 150 minutes of protection. SPF30 gives you 30x10 or 300 minutes of protection (double the time of SPF15):

SPF15 = 150 minutes SPF30 = 300 minutes
  10 minutes   10 minutes

However, the amount of UVB rays that are absorbed is NOT double. It is calculated as follows:

SPF15 allows 1/15 or 6% of the UVB rays to get through to your skin, giving 94% UVB protection.

SPF30 allows 1/30 or 3% of the UVB rays to get through to the skin, giving you 97% UVB protection.

Ingredients To Look For In A Sunscreen

For UVA protection:

  • Avobenzens
  • Mexoryl SX
  • Tinasorb
  • Triazine

For UVB protection:

  • Methyoxycinnamate
  • Homosalate
  • Octocrylene
  • Sulfonic acid
  • Tinosorb
  • Triazine

Other ingredients:

  • Titanium dioxide (absorbs and reflects UVA and UVB)
  • Zinc oxide (reflects UVA and UVB)