To be clear, I had not been refining in the house but rather outside. Still not as safe as having a fume hood, but better at least. I stored the metal from my only attempt at PGM refining in the house though, and I obviously stored it very improperly. I did this several months ago and have no desire to attempt PGM refining again - it's obviously far too dangerous for my crude setup.
It was a stupid mistake. I left a beaker containing the 0.5 g of mixed PGMs as the black powder (they had been thoroughly washed and no salts were present) in a beaker with a watchglass on it, on top of an old computer on a wire shelf filled with other random things. It was right next to some homemade soap. This morning, I realized I was out of soap in the shower, so I went over and reached for the soap but knocked over the beaker, which fell to the shelf below, spilling a small amount of PGM powder onto various items on that shelf and the floor below.
My impression of the safety of PGM metal dust is that it does not have anything like the toxicity of the salts - it's fairly similar to other metal dusts in being a problem in high concentrations or for long periods of time, but a small amount of spilled dust is unlikely to cause problems. I'm very happy to be corrected about this though.