Comment by Clamchop

You don't smell particles, you smell volatile compounds, mostly organic, aka VOCs. These are in their gas phase.

This is true of anything that smells. Food, flowers, the forest, breath, body odor, rain on dry ground, your car...

Many ingredients used in modern perfumery (scenting your detergent is still perfumery) are novel compounds, like galaxolide, but traditionally and still often enough they are naturally-occurring chemicals, although still synthesized in a factory from petrochemicals a lot of the time.

Article seems to be about a chemical reaction of terpenes with ozone, and the result is particles. Terpenes are a specific but large class of aromachemical, both natural and artificial. There are many others.

Even products marketed as unscented tend to be scented, to mask off odors from their functional ingredients.

Just adding some context.