@rick i did yes, I do have 3M HF-800SD with D9038 filters although it's not exactly the best fit for covid stuffs because of exhalation valve, there's stuff like msa advantage 900, which is a better fit not an expert in this at all
@rick@erincandescent@lilian generally you should change them when you feel that it's harder to breathe, at least that's according to the manual there's also the general expiry date which I am not sure of