They wore masks, had negative pressure ventilation suits on

I hope those were positive pressure suits, positive pressure helps to keep dust out of the suit. Negative pressure ventilation is used to help sick people breathe easier, like the iron lung for example.

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What’s wrong with using a text editor to remove lines ? In vim for example :g/pattern/d or :g!/pattern/d with regular expressions is a powerful tool for removing lines in bulk if needed.