What SPF You Should Use


Photo Credit: Dr Sylvia Skin Care


The harmattan is finally here, and I can literally hear a lot you screaming yippee yeah! Well, you can only do that if you are already prepared to protect yourself from the extreme changes in temperature this season is popularly known for. Harmattan is a season in West Africa that occurs between November and March. It is characterized by extremely cold and fuggy mornings, dry, dusty, and very hot days with the sun at its peak, and then warm or cold nights depending on local circumstances.

You can refer to it as the dry season at its peak. The temptation to wear less clothing during the day, but cover up until you are almost invisible in your clothes at night is on the rise. The increased risk of photosensitivity, sunburn, sunstroke, tanning, and hyperpigmentation is high, yet many beaches are getting crowded, a lot of swimming is going on, and most ladies literally want to walk the streets naked because of the heat (if only pigs would fly, then they can right?).

I talked about sunscreen the other time and how important it is at this time of the year. I got so many feedbacks and questions from you all. I was able to answer few questions, and from my findings, decided to explain certain things like SPF, and what kind you should use. Since many of you see sunscreens with SPF written on them, and honestly do not know what it means, I believe a little explanation from me will be helpful. Let’s dive right in.




SPF simply means Sun Protection Factor. A sunscreens SPF is a relative measure of how well it protects your skin from UVB rays from the sun. The number 10, 15, 30, 50 written on a sunscreen tells you that it would take 10, 15, 30, 50 times as long to produce a slight redness or sunburn from the sun’s UVB rays if you use the sunscreen as directed compared to the amount of time without the sunscreen.

So, if it takes your skin 30 minutes to develop a slight redness or sunburn, and you use a sunscreen with an SPF of 30, it would take 15 hours to develop the same amount of redness or sunburn with the sunscreen. This also applies to the other numbers used for SPF. It is important to note that SPF is a measure of the amount of protection your sunscreen gives you from UVB rays, and not the measure of duration of exposure to the sun’s UV radiations.

Having this in mind, do not assume that by wearing a sunscreen, you can stay out too long under the sun. This is merely a rough estimate that depends on your skin type.


I would say yes but not always with reasons. The obvious reason is not all high SPF sunscreens offer broad spectrum protection. Also, while sunscreens with higher SPF are proven to block, reflect or absorb more UV rays, and there is a huge difference between SPF 10 and 20, SPF 15 and SPF 30, but a significant decline as the number climbs above SPF 30. Below is a run-down of what I mean.
 SPF 15 gives 93% protection by allowing 7 out of 100 photons from UVB rays through.
 SPF 30 gives 97% protection by allowing 3 out of 100 photons from UVB rays through.
 SPF 50 gives 98% protection by allowing 2 out of 100 photons from UVB rays through.

So, a sunscreen with SPF 30 gives you 4% more protection than the one with SPF 15. Note that any SPF with a higher factor like 75, 100 etc, do not offer any significant better protection than SPF 30 and SPF 50. In my opinion, they are simply marketing strategies used to lure ignorant consumers into buying their products as a better option to other lower factor sunscreens.


Before we go into that, let me tell you about the different types of UV radiations and their effects on your skin. There are 3 types of radiations emitted by the sun, and they are UVA, UVB, UVC radiations. Only the UVA and UVB radiations reaches the earth surface. This is because the UVC radiations are absorbed by the ozone layer, but they can still be found in tanning beds, welding lamps and torches etc.

UVA rays constitute 95% of the UV radiation that reaches the earth from the sun. They cause skin damage such as premature aging, skin tanning and skin reactions to medications, soaps, cosmetics, and other chemicals. They also contribute to skin cancer.
UVB rays constitute 5% of the UV radiation that reaches the earth from the sun. They damage your skin’s DNA, and are the major culprits for redness, sunburn and skin cancer.

Broad spectrum sunscreens protect you from the harmful effects of both UVA and UVB. They usually combine some of these ingredients such as avobenzone, octocrylene, octinoxate, benzophenone (oxybenzone), titanium dioxide,zinc oxide etc.

SPF 15 sunscreen is ideal for occasional everyday exposure such as morning and evening walks, driving to work, exercising your pet etc.

SPF 30 or higher sunscreen is ideal for long exposures outdoors such as sporting activities, street retailing or vendor business etc.


Photo Credit: J. Kevin Poitras, MD



SPF only measures your sunscreen’s effectiveness against UVB rays, and this makes a sunscreen’s sun protection incomplete. Window glasses can block UVB rays but they cannot do so with UVA rays. This explains why you must wear your broad spectrum sunscreen always even in cloudy weather and when you are indoor. Some protective clothing helps prevent damages from the sun. I will explain that in detail probably in my next article.
Persistent Pigment Darkening (PPD) is a method for measuring UVA protection. A sunscreen with a PPD rating of 15 should allow you 15 times more time in the sun unlike when you are without sunscreen protection. This is not usually written on the body of most sunscreens but some European made sunscreen shave it. Colipa has introduced a method that it claims can measure this in vitro while providing equal results like PPD method.

By looking at the infographic above, you will easily understand everything. I will never over emphasize on the importance of a sunscreen. You don’t have to get a horrible sunburn or cancer before you sit up and take notice. Do you still need to be persuaded to get a sunscreen? Be safety smart. Be safe. Love yourself.


  1. A good and enlightening write-up on SPF. I guess whites have more to worry about SPF than blacks since dark pigmented skins have a superior barrier function than white pigmented skins both against UV and microbial penetration.


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