A distinctive feature of diacetyl (and other vicinal diketones) is the long C–C bond linking the carbonyl centers.

[8] People nearby may be exposed to it in the exhaled aerosol at levels near the limit set for occupational exposure.

The makers of some wines, such as chardonnay, deliberately promote the production of diacetyl because of the feel and flavor it imparts.

[11] Diacetyl is present in some chardonnays known as "butter bombs", although there is a trend back toward the more traditional French styles.

[13][14] Chronic industrial exposure to diacetyl fumes, such as in the microwave popcorn production industry, has been associated with bronchiolitis obliterans, a rare and life-threatening form of non-reversible obstructive lung disease in which the bronchioles (small airway branches) are compressed and narrowed by fibrosis (scar tissue) and/or inflammation.

[15][16] The European Commission has declared diacetyl is legal for use as a flavouring substance in all EU states.

[20] Manufacturers of butter flavored popcorn including Pop Weaver, Trail's End, and ConAgra Foods (maker of Orville Redenbacher's and Act II) began removing diacetyl as an ingredient from their products.