Last week we explained the different implications of sun exposure and the danger of UVA and UVB rays. Do you still recall the formula to differentiate between A and B rays?
That’s right – UVA Ages Skin, UVB Burns skin.
This week, we’re moving on to the types of Sun Protection Standards and what they mean – an important thing to note when we’re choosing our sun protection!
SPF: SPF stands for sun protection factor. This measures the amount of time a product protects your skin from reddening due to exposure to UVB rays. For example, if it takes 20 minutes before your skin starts to redden when exposed to the sun without any protection, an SPF of 15 will prevent your skin from burning for 15 times longer. (20×15=300 mins) This means you can be in the sun for 5 hours with an SPF 15 product, before your skin starts getting damaged.
If you’ve taken note of the above, you’ll realise that contrary to popular belief, a higher SPF doesn’t mean stronger protection, just a longer period of protection. So if you work in an office all day and are only exposed to the sun for only 30 minutes each way when commuting to and fro, you probably won’t need a product with SPF 45. The Skin Cancer Foundation recommends that you use products with at least SPF 15, a minimum that should work for most people, unless you work in a mainly outdoor environment.
Since SPF measures the reddening of skin, this universal standard is mostly useful for gauging the protection against UVB rays (The rays that burn skin! Remember?). Currently there is no worldwide standard for UVA protection, so you’ll need to check the ingredients in your product to ensure that there are also UVA resistant products in there to safeguard your skin against the effects of photo-aging, caused by those UVA rays! (What ingredients? Look out for part III…)
PA: In the meantime, you can look to the PA system for a better gauge on UVA protection. PA is a Japanese sun protection standard based on the PPD (Persistent Pigment Darkening) reaction readings. PPD measures the damage to our pigment cells after every 2 – 4 hours of sun exposure. This reading helps to determine the PA (Protection level of UVA) of a product.
There are currently 3 levels of PA:
PA+ : Some UVA protection with a PPD of 2-4 (meaning our pigment cells will start getting damaged after 2-4 hours of sun exposure)
PA++: Moderate UVA protection with a PPD of 4-8. (Skin is protected for 4-8 hours)
PA+++: Good UVA protection with a PPD of >8. (More than 8 hours of sun protection)
So again, you can use this standard to match your sun protection product to your needs. Since UVA works on an invisible level compared to UVB, they’re more dangerous, so a higher PA factor might be a safer bet.
Next Week: The difference between sun screen and sun block, and the types of sun protection ingredients to look out for!