Over 80% of sunscreen performed below their labelled efficacy (2020)

This is a topic where the details matter a lot. A sunscreen which is labeled SPF 50 but performs at SPF 45 is such a minimal difference that it would be impossible to notice in the real world. The variance of your application technique and applied thickness would actually matter more. There is also a lot of testing variability, so if a sunscreen rated to block 98% of certain rays only gets 97% in the test that would be acceptable in the real world, but it would get counted for this clickbait headline.

If a sunscreen comes with a high SPF rating and performs close enough in random testing (which is hard to replicate) then I wouldn’t have any concerns in the real world.

The body of the article has some more details about how the number of majorly deficient brands was much smaller, but that makes for less clickbaity headlines:

> The measured sunscreen efficacy of 4 models were below SPF15, of which 2 were sunscreen products with very high protection i.e. labelled with SPF50+

Knowing which 2 brands were labeled SPF 50 but performed below 15 would have been helpful, but the article is not helpful.

This is related to an article from yesterday, https://news.ycombinator.com/item?id=45145624, about the Choice Australia investigation that found that some sunscreens (named in that article) provided around SPF 4 when it was labeled as SPF 50+. It is a big deal because many people (like the 34 year old woman in the article who had skin cancer removed from her face) use a specific brand for years, believing it to be as effective as the label proclaims.

As someone who burns extremely easily, I'm confused how this happens. I can feel the difference immediately; as little as ten minutes in direct sunlight makes me tinged red; and if I don't cover every inch I can tell which parts I missed the next day. If it doesn't work why would you use it?!

I do have sympathy for those with dark(er, which is basically everyone) skin who may not be able to directly tell the efficacy.

My concern is that mineral sunscreens are difficult to apply and leave a film on the skin (which is the entire point, I guess?); i hate that feeling, so I use chemical sunscreens. I'd bet that some of them have very nasty long-term side effects. So in the end i almost always go with trying to cover my skin with clothes/shade/whatever if at all possible.

Why are you confused? You can be (and are likely) doing deep, long term damage to your skin even if your skin doesn't have an immediate reaction to sun exposure (i.e sunburn). This is a key point that cancer council australia are constantly trying to drill into peoples heads.