alt Hacker NewsRespirators can't do anything about volatile components that have low boiling points: sulfur and nitrogen oxides, hundreds of often carcinogenic aromatic hydrocarbons released by burning any organic matter. If you wear a good FFP3 respirator in heavily polluted air, it's very noticeable that it doesn't filter out everything — the smell gets through. And it's a specific smell, reminds me of walking through charred ruins of a building that has burned down 5-10 years ago and never rebuilt.
I had a notable experience at a church sometime during COVID, where I was wearing an N95 mask. The church’s incense could be smelt partially through the mask, and the scent that made it through was much worse than the combined scent that you normally smell.