I would guess that it works similar to a water pump- pushing is always more powerful than sucking - but check this out for some detailed analysis (and more data

I would guess that it works similar to a water pump- pushing is always more powerful than sucking - but check this out for some detailed analysis (and more data on DIY air filters) https://smartairfilters.com/en/blog/where-should-an-air-filter-be-placed-relative-to-the-fan-for-best-efficiency/ https://smartairfilters.com/en/blog/where-should-an-air-filt...