So a T-Shirt is 50% as effective as a mask, and a mask is not terribly effective in the first place? OK, score one for the T-Shirt.

I never said a mask was useless. I said, "A mask may have some effect in protecting you from getting a virus. A very minimal effect."

I also said, "They will be much more effective in preventing you from spreading the disease you have, rather than protecting you from getting the disease you don't want to get."

Personally, I would not bother with a mask (to try to protect myself), I would simply maintain distance. But I have no problem with anyone who wants to wear a mask. However, I would wear a mask when visiting the elderly, even if I were symptom free. As well as maintaining distance. And washing my hands the moment I walked into their home. that's exactly what I do when visiting my elderly piano teacher (lessons are off for now, but I still stop by to deliver things). Additionally, I use a plastic bag as a make-shift glove when touching her doorknob to let myself into and out of her house, after the briefest of brief visits needed to get the job done. Unfortunately, my supply of masks can be counted on one hand, so I have to re-use them. That is not ideal.