This potential hazard is not well understood yet, so don't immediately throw your 3D printer away, but it's something to keep in mind. I think there was a round of these studies done a couple of years ago too.
New Study Details Toxic Particles Spewed by 3D Printers https://gizmodo.com/new-study-details-all-the-toxic-shit-spewed-out-by-3d-p-1830379464 via @gizmodo
@jmwright Incense and candles are also sources of nano-pollution:
Rather than worry about such stuff, I just keep the windows open.
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