"The researchers used air samplers which are fitted with a metal substrate. Air passes through the sampler, and particles from the atmosphere deposit onto the substrate. Then, using light-based spectroscopy, the researchers are able to determine what kind of particles are found on the substrate.

Clough prepared the substrates while wearing nitrile gloves, which is recommended by the guidance of literature in the microplastics field. But when she examined the substrates to estimate how many microplastics she captured, the results were many thousands of times greater than what she expected to find."

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The very first thing that should have been done is to run results for a substrate that hadn't been placed in the sampler. You need to know what a zero result looks like just to characterize your setup. You'd also want to run samples with known and controlled micro-plastic concentrations. Why didn't they do this? Their results are utterly meaningless if they didn't.

That does seem like an oversight. We routinely run process blanks for elemental analysis at my job. I guess if the metal substrates had specifications on no particles you might skip this, obviously a big mistake if another step (ie. handling with gloves) introduced contamination.

In surface science the baggy clear polyethylene are widely known to be cleaner than other options.

Yeah, where is their control sample without any substrate on the sampler?