Isolation and distancing will be much more effective than a respirator, which will just make you sweaty and may even provide an infection vector if you don't have the means to keep it absolutely clean.
Even among high-risk people, the actual risk of serious unpleasantness is fairly low so hopefully they'll be okay. The reason they're making such a big deal of it isn't the individual risk, where it's unlikely to become very serious, but that a small risk when multiplied by the entire population (and it is very infectious indeed, much more so than common 'flu: though 1.3 vs. 2 new infections per person doesn't sound much, exponentially it makes a gigantic difference, e.g. assuming both have a five day cycle, over two months assuming a cycle time of 5 days i.e. 12 infection cycles, 1.3¹² would mean 23 new infections, whereas 2¹² would indicate 4,096 new infections. That's a lot of assumptions and not to be taken absolutely literally but it demonstrates the problem) means very quickly overwhelmed critical care units which would make the entire health service cease to function. And other health problems haven't gone on holiday for the duration.
Er, so anyway, that is why it's such a massive big deal at the same time as personal risk is very low and hopefully that will be the case with your relatives.
I understand that children are relatively resistant to the disease. I mean we were all little plague-carriers once and were virtually unkillable!
