Title, journal, date and first author checked against the publisher’s Crossref record on 2026-10-24 by an automated check. Publication date confirmed to the day. Open licence reported by the publisher: CC BY 4.0. SmellBook publishes only the citation and its own claim, never the work’s text.
In a study of 17 coffee roasting and packaging facilities that included 10 cafés, baristas in cafés had mean full-shift exposures of 4.1 parts per billion diacetyl and 4.6 parts per billion 2,3-pentanedione (geometric means), measured in personal air samples.
Ten cafés, nine of them sampled, belonging to the US coffee roasting and packaging companies studied, all at facilities not flavouring coffee during the survey, some on the roasting site and some elsewhere; the café results are not separated by location. The barista results come from 14 personal air samples worn by 13 baristas over a work shift: occupational air composition, not the smell of a coffee shop; neither compound is named as the cause of any smell; not every coffee shop; the study's health and exposure-limit findings are outside this claim.