>In my experience, people often overestimate how much protection ventilation provides.

Do you have references to back this up that I could read? Assuming the same fan size, ventilation would act like a perfect filter and remove everything out of the room that the fan pushes, whereas a filter will allow some particles to pass and recirculate. Especially useless if it is those metal fiber filters that are in a range hood that just remove some grease.

Yes, ventilating out > recirculating no question! I just wanted to raise awareness that ventilation is not instantaneous. It takes time to bring things back to safe levels in case of spikes.

A quick search brings up the CDC guidance, where they discuss air changes per hour for a room. This will be for HVAC units, which operate on a completely different magnitude of airflow compared to a kitchen extractor fan.

https://www.cdc.gov/infection-control/hcp/environmental-cont...

This also matches my experience in industrial applications, you only need a single failure point such as a spill or a large enough leak and ventilation alone is no longer enough to keep people safe. This is why it's worth considering a glove box/isolator. You could make the argument that a glove box can also leak and I'm starting to sound like a safety engineer. Anyway at home either will be fine with outside ventilation being superior if done right.