What do SPF, broad spectrum, UVA and PA mean?



In Singapore, we have MRT, KPE, MOE, NTUC, GST, SGH….

Acronyms make life simpler and presumably, allow you to talk faster. But if you are not local, these abbreviations could be mind-boggling. Similarly, sunscreen acronyms were created to simplify sunscreen labels to let you make more informed choices. Here’s a guide on what they mean, and how to read sunscreen labels from around the world.

Most of us are familiar with the abbreviation SPF. The United States was the first to use the Sun Protection Factor as the standard for sunscreen in the 1970s. SPF measures the duration you could spend in the sun without getting a sunburn. For example, if your skin burns after 10 minutes in the sun, an SPF-15 sunscreen allows you to stay up to 150 minutes longer without getting a sun burn. The SPF levels ranges from two to near 100.


Three Things You Need To Know about SPF

No sunscreen is expected to provide more than 120 minutes of UV protection. Even if the sunscreen is supposed to give you 150 minutes of protection, re-apply every 120 minutes or after sweating or swimming. There is concern over the photo stability of the ingredients with prolonged sun exposure. The ingredients may break down in the sun or are washed away with sweating or swimming.

The second thing you need to know is the Law of Diminishing Returns applies to SPF. The amount of UV-B protection from a higher SPF value decreases, and is negligible with SPF above 50. SPF 15 offers 93% protection from UV-B radiation, and SPF 30, 97% protection. SPF 50 gives 98% UV-B protection.

It is difficult to improve further from here, and no sunscreen would claim to give 100% protection from UV-B, so sunscreens marketed with SPF 70, 80 or even 90 are not giving you significantly more sun protection even though they are likely to cost more. The US regulatory body, the Food and Drug Administration, has proposed sunscreens with SPF higher than 50 to be simply labeled as SPF 50 plus. Promoting ever-higher SPFs on the label misleads consumers into believing that they are getting more protection than they really are, said FDA.

SPF values of 15 to 50 are generally recommended as giving adequate protection from UV-B in addition to applying enough amount of sunscreen on the skin, seeking shade and wearing protective clothing.

The third thing you need to know about SPF is it measures skin protection from UV-B, and not UV-A. It was in the 1980s that scientists discovered how deadly UV-A is on the skin. Although UV-B is the primary cause of sunburn, research found UV-A could penetrate deeper into the skin’s surface to alter the DNA of skin cells. Prolonged exposure to UV-A radiation causes pre-mature ageing, and has been associated to the more deadly form of skin cancer, melanoma. Prior, UV-B was largely blamed for causing sunburn and skin cancer. The SPF rating, which measures the rate at which sunburn occurs, is no longer enough as a standard for sunscreen. It is also necessary to find a method to measure UV-A protection.


Deadly UVA spurs new standard & ingredients

With the discovery of the harmful effects of UV-A radiation, sunscreen manufacturers soon realized that many chemical sunscreen ingredients were excellent in protecting the skin from sunburn (UV-B,) but not (UV-A.) A race thus began among major sunscreen manufacturers to be the first to create a new chemical sun filter, that would be just as good in providing UV-A as -B coverage. A new generation of chemical ingredients, notably Meoryxl and Avobenzone were created in Europe, which give good UV-A and -B protection.


FDA sets rule for broad spectrum

New terminologies and regulation were also needed. So in the U.S., the term “broad spectrum” was coined for sunscreens which give both UV-A and -B protection. In 2011, the U.S. government agency, FDA, regulated the use of the term, “broad spectrum” with a new labelling rule on sunscreen. In order to carry the words, on the front label of the sunscreen, the sunscreen has to provide both UV-A and -B protection that meet the FDA standard. To meet the FDA requirement, the sunscreen must have a Critical Wavelength of at least 370 nm.

Related Story: The U.S. gets tough on sunscreen claims

To protect the consumer further, the SPF level should appear prominently on the front label of sunscreens sold in America. FDA set the SPF 15 as the minimum standard of UV-B protection. A sunscreen with SPF lower than a level of 15, and do to meet the FDA definition of “Broad Spectrum” has to carry the following health warning:

“These products have not been shown to protect against skin cancer and early skin aging. They have been shown only to help prevent sunburn.”

Sunscreens that meet both criterion — “Broad Spectrum” and SPF 5 or higher — should carry a recommendation on the back of the label that reads:

“If used as directed with other sun protection measures, this product reduces the risk of skin cancer and early skin aging, as well as helps prevent sunburn.”

The new labelling rule, known as the FDA’s Final Rule because it went through several revisions before it was passed in 2011. Manufacturers were given another year to update all their product labels to comply with the new ruling.


Europe creates UVA logo

In Western Europe, the changes on sunscreen labels were made through the EU Recommendation in 2006. A UVA logo was introduced, and in order to carry the logo, sunscreens must provide UV-A protection of at least one-third of the UV-B protection. The UVA measurement in Europe is based on the Critical Wavelength measurement like the US, in addition to the UVA/UVB ratio where the level of UV-A protection is measured as proportion to UV-B


To help consumer better understand SPF, beside displaying the SPF level on the label, the label should also carry an accompanying table that rates SPF levels from 6 to 50 plus on a scale of Low-to-Very High Protection.

In Britain, retailing giant Boots is largely credited in creating an UVA star rating, which improves on the EU labelling recommendation. How does it work? The stars range from 3 to 5 and indicate the level of UV-A absorption of the sunscreen as a ratio of UV-B. With the star system, you would be able to choose a sunscreen with UV-A protection that is higher than the minimum to earn the EU’s UVA logo.

However, be aware that when you select a sunscreen with a low SPF, it may still have a high level of stars, said the British Association of Dermatologists. This not because it is giving you lots more UV-A protection, but because the UV-B protection is about the same. The calculation is based on a ratio of UV-A and -B, so it’s important to choose a high SPF, with a high UVA protection (e.g. a high number of stars.) The British Association of Dermatologists recommend a sunscreen with SPF 30 and an UVA rating of 4 or 5 stars in addition to shade and clothing for sun protection.


Japan & South Korea adopt PA star rating

You would notice sunscreens and beauty products from Japan and South Korea, carrying PA star rating on the label. PA is a short code for the Protection Grade of UV-A. The stars are from 1 to 4, and indicate the duration needed for the skin to darken with UV-A exposure. The test is known as the Persistent Pigment Darkening Method, and was created by the French cosmetic giant, L’oreal. The Japanese trade organization added the star rating in 2013. Look for PA stars of 3 or 4 for good UV-protection.

Related Story: How Safe are BB creams?

The PA star rating is an in vivo method, which means human subjects are used in the test. North Asia is the only region to require in vivo test on sunscreen to measure UV-A protection. In contrast, an in vitro method is one conducted in a laboratory where the sunscreen is applied on a film or a substrate. It is exposed to UV radiation to create a spectrum of wavelengths, which are measured. Examples of in vitro methods are the critical wavelength method used in the US, and the ISO 24443 method used in Australia. Europe also used a PPD method to measure UV-A like Japan, together with critical wavelength. But the PPD testing are done via in vitro or in vivo.

In vivo tests are better in determining the photo stability of the sunscreen compared with in vitro tests. But exposing humans to high dosage of UV radiation raises ethical questions when there are alternative assessment methods.

Table 1_ BASF sunscreen simulator

Table 1: BASF Sunscreen Simulator (table source: BASF)


Above is a table showing the test results of five sunscreens with SPF 20. Compiled by German chemical company, BASF, the table compares the UVA protection of the five sunscreens based on the different UVA assessment methods around the world. BASF did not disclose the names of the sunscreens.

The table showed sunscreens like C, D and E which could meet the UVA test standard in the US, with each having critical wavelength of above 370 nm, would also meet the criterion in Europe (carry the UVA logo and Boots 3-5 stars) and North Asia (at least PA +++.) Meanwhile, both sunscreens A and B failed in the UVA assessment tests across the region.

Are you now proficient in sunscreen acronyms. Could you say them in one smooth sentence? When buying a sunscreen, choose one with an SPF of between 15 and 50. Remember, don’t just look at the SPF level, but also if the sunscreen carries the words, “Broad Spectrum” (from the U.S.) or the UVA logo (from Europe,) or has many PA stars (from Japan) on the label.


FDA Sunscreen Label – Consumer Update, US’ Food and Drug Administration.

Sunscreen Fact Sheet, the British Association of Dermatologists.

Osterwalder, Uli; Champ, Samantha; Flösser-Müller, Heike; Herzog, Bernd. The Evolution of UVA Protection. BASF Skin Care Forum. 2013, September.



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