I understand it’s probably a more complex issue, but could it be similar to a 4th grade science project where you filter water through a bottle with a variety of rocks, sticks, moss etc?
Because you can filter out large chunks of debris from water using filters, but can’t filter dissolved salt out.
Filtering toxic fumes is equivalent to that, when toxic molecues are pretty similar to air molecules when it comes to their abilities to pass through a filter.
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