> Such a frustrating article. Does it work! That's all I want to know!

There is not seal. It sends a flow of filtered air towards your nostril but that flow mixes with the surrounding air. Anecdotal reviews all talk about how they can smell the surrounding air, meaning that particles get into your nose and then lungs. I saw a review by a doctor discussing about how having a constant flow of air pointed at the nose will dry the nasal mucosa which would offset any advantages from the flow of mixed fileted/non-filtered air.