OP here.

I've started gathering data on KN95 mask prices after seeing the same KN95 products from AliExpress being sold for 10x prices on European marketplaces. My goal with this project is to raise awareness about alternative marketplaces and fight price gouging. The data is available on Github [1] and it will be hopefully useful for others as well.

Of course, one can be never certain which products actually qualify as KN95 masks, but my position is that, I'd rather be wearing a mask that has the required layers for a KN95 mask, than a surgical mask, even if it may not fulfill the filtration criteria, because of the better fit.

[1] https://github.com/abiro/mask-price-data

Though, the cheap masks you have there are not eligible for shipment to the United States. It would be nice to see ones that are available for shipment to the U.S.

Thanks for making this. What scares me about a mask is that it could do more harm than good: if it's made with non-safe materials I am breathing through it for hours on end, bad things might happen.

I'd like to order from Ali Express but have no way of judging safety or knowing if the certifications are enforced. With a European distributor I hope that they are.

Do you have any tips on judging if a mask is going to be safe?

I look at the reviews, the number of items sold, and don’t pick the cheapest one. The best is if there are reviews that show a mask cut open and you can see whether it has the required number and type of layers.

I’m not too worried about unsafe materials, but if you don’t feel comfortable with it, don’t order them. The safest thing you can do is buy masks from a pharmacy in person if they are available.