Exposure to diacetyl endangers coffee roasters

The smell of roasting coffee is one of the things that draw people to artisanal coffee shops. People who live or work around large-scale coffee roasting operations also enjoy this smell as they are out and about.

But a hidden chemical in that aroma present a significant risk to people who work in and around coffee roasting operations. It’s called diacetyl, a chemical used to flavor coffee. Other chemicals with the potential to harm people working in coffee roasting facilities include 2,3-pentanedione, and 2,3-hexanedione.

A study completed by the National Institute of Occupational Safety and Health (NIOSH) revealed some disturbing news. Workers in coffee processing facilities who routinely inhale vapors produced during the roasting process have an elevated risk for contracting bronchiolitis obliterans, popularly known as popcorn lung. This is a very serious lung disease that can require life-long medical treatment.

Results of the NIOSH coffee roasting study

At the request of the management at a coffee roasting facility, NIOSH measured the amount of diacetyl, 2,3-pentanedione, and 2,3-hexanedione in the air, as well as other gases such as carbon monoxide and carbon dioxide. Samples were collected at the roaster, the grinding apparatus and the packaging area.

 Over the course of a full shift, some workers in these areas were exposed to diacetyl at a level that exceeded the recommended exposure limit of 5 parts per billion. The highest level measured was 8.4 parts per billion.

The maximum diacetyl levels measured over shorter periods were far higher:

• Grinding roasted coffee beans – 37.6 parts per billion
• Blending roasted beans by hand – 33.4 parts per billion
• Weighing and packaging roasted coffee beans – 34.3 parts per billion

Workers examined as part of the study were found to have eye, nose, sinus and respiratory problems. One out of sixteen workers studied had high levels of exhaled nitric oxide, an indicator of respiratory inflammation. Long-term exposure to high levels of diacetyl has been linked to bronchiolitis obliterans, a serious lung disease.

What coffee roasting workers can do

The NIOSH report provides this advice to workers in coffee roasting facilities:

• Operate the exhaust fan at all times. If it is clogged by dust or obstructions, ask management to clear those substances.
• If weather permits, open windows or doors to allow fresh air to enter the facility.
• To the extent you can, avoid placing your head into bins containing roasted beans.
• Ask management to provide N95 disposable respirators for use when emptying burlap bags containing green coffee, cleaning the roaster exhaust shaft, and cleaning the green bean storage area.
• If you notice respiratory problems, get medical attention.

 Employees of coffee roasting facilities who have contracted popcorn lung, or who have suffered adverse health effects from workplace conditions may be eligible for workers’ compensation benefits. Speak with an attorney if your claim has been denied or delayed.

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