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.

No, it should be like car speedometers where even a slight misreading on the wrong side is regulated harshly. [1]

I don't care for "close enough" brinksmanship.

The same is true for speed limits but y'all aren't ready for that

[1] Might be rumor but I heard that car speedometers often read high because there's a big penalty if they read low by even 1 MPH

It's not a rumour. They usually read somewhere between 5-10% over actual speed. Use a more accurate GPS speedometer on your phone to check that.

5-10%, definitely not. Wrong tire size will do that though.

Have had a GPS speedo on the dash for a good dozen cars through the years and never seen more than a few mph off on a flat surface. That's something I actually noticed and looked for, for some reason. A few mph over speed is fairly common, but we're talking 1-2% at most. (confirmed with Tesla Model 3, Corolla, Fusion, Prius, Elantra, Mirage, etc etc).