That is literally true, but the playa dust will not be on my negatives. It's on the old Coleman stove sitting on the floor that I plan to clean off tomorrow. The full explanation is that my darkroom is not sealed and the air is not filtered. My standards are decidedly NOT critical. I work in black and white and consider dust a problem up until the negative is exposed. After that, dust becomes a white speck on the print that is easy to spot.