They are just fine if the idea is to protect oneself from dust, but here we are talking of protecting from a virus (and to protect others, so valved masks are not suitable).

Rough correspondence:

FFP2 is 94%

N95 is 95%

FFP3 is 99%

Source (an UK firm):

http://www.ashsafety.com/tips/filterClass.htm

> Finding a suitable respirator is not just a matter of choosing a model you like or by the cost of it. You may need to try different makes or sizes to find one that fits without leaking around the seal and letting dust in. A respirator that depends on face fit is ineffectual if you have a beard or thick beard stubble. The only way you can know if the seal is good enough is by having a proper respirator fit test. At present this is also the only way of meeting legal requirements.

And here is (again UK firm) how a fitting test works:

https://www.xamax.co.uk/blog/how-to-respirator-face-fit-test...