Health Hazard Evaluation Report 2017-0020-3316 Page 1

Evaluation of exposures and respiratory 

health at a coffee roasting and flavoring 

facility 

Report No. 2017-0020-3316

April 2018

Ethan D. Fechter-Leggett, DVM, MPVM

Alyson R. Johnson, MPH

Stephen B. Martin, Jr., PhD, PE

Michael P. Grant, ScD

U.S. Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health
Page 2 Health Hazard Evaluation Report 2017-0020-3316

Contents

Highlights.............................................. i

Abbreviations ...................................... v

Summary.............................................. 1 

Introduction......................................... 2

Background.......................................... 2

Process Description............................. 6 

Methods ............................................... 8 

Results ................................................ 13

Discussion .......................................... 16

Conclusions........................................ 22

Recommendations............................. 22

Appendix A: Tables............................ 27

Appendix B: Figures .......................... 33

References.......................................... 34

Acknowledgements........................... 44

The employer is required to post a copy of this report for 30 days at or near the 

workplace(s) of affected employees. The employer must take steps to ensure 

that the posted report is not altered, defaced, or covered by other material.

The cover photo is a close-up image of sorbent tubes, which are used by the HHE

Program to measure airborne exposures. This photo is an artistic representation that may

not be related to this Health Hazard Evaluation.
Health Hazard Evaluation Report 2017-0020-3316 Page i

We evaluated respiratory health and 

airborne exposures to alpha-diketones 

(diacetyl, 2,3-pentanedione, and 

2,3-hexanedione), other volatile organic 

compounds, carbon monoxide, and 

carbon dioxide during coffee roasting, 

flavoring, grinding, and packaging. All 

four of the personal full-shift samples 

collected in the production area 

exceeded the NIOSH recommended 

exposure limit for diacetyl of 5 parts 

per billion. One of the four personal 

full-shift samples collected in the 

production area exceeded the NIOSH 

recommended exposure limit for 

2,3-pentanedione of 9.3 parts per 

billion. In addition, air sampling during 

short-term tasks identified several tasks 

(e.g., flavoring roasted coffee beans 

and grinding flavored and unflavored 

coffee) with higher exposures to 

alpha-diketones, including diacetyl, 

than other tasks. Air concentrations 

of diacetyl and 2,3-pentanedione 

increased over the course of the work 

shift. Some employees reported eye, 

nose, or sinus symptoms or wheezing or 

whistling in the chest. We recommend 

installing local exhaust ventilation 

near flavoring and grinding activities, 

implementing administrative controls 

such as modification of work practices, 

and training employees about workplace hazards. We also recommend 

instituting a medical monitoring 

program.

Highlights of this Evaluation

The Health Hazard Evaluation Program of the National Institute for Occupational Safety 

and Health received a request from management of a coffee roasting and flavoring facility 

regarding concerns about repetitive motion injuries, potential burns, general warehouse 

safety, and exposures to and health effects from green coffee bean dust, diacetyl, and 

2,3-pentanedione during coffee processing. 

What We Did

● We visited the coffee roasting and flavoring 

facility during January 10–12, 2017.

● We collected full-shift (hours), task (minutes), 

and instantaneous (seconds) air samples 

to measure concentrations of the alphadiketones diacetyl, 2,3-pentanedione, and 

2,3-hexanedione.

● We collected roasted coffee beans (whole 

bean) and liquid flavoring to measure 

their emission potential for diacetyl, 

2,3-pentanedione, and 2,3-hexanedione.

● We measured real-time air levels of carbon 

monoxide and carbon dioxide.

● We administered a health questionnaire to 

employees and performed breathing tests. 

● We observed production practices, including 

receiving green bean shipments, storage, 

roasting, flavoring, grinding, packaging, and 

preparing for delivery and shipment.

What We Found

● During personal full-shift sampling, some 

employees were exposed to diacetyl at 

concentrations above the National Institute 

for Occupational Safety and Health 

recommended exposure limit for diacetyl of 

5 parts per billion, with the highest measured 

concentration of 20.7 parts per billion. 

● During personal full-shift sampling, one 

employee sample was above the National 

Institute for Occupational Safety and Health 
Page ii Health Hazard Evaluation Report 2017-0020-3316

recommended exposure limit for 2,3-pentanedione of 9.3 parts per billion with a 

measured concentration of 24.0 parts per billion.

● Levels of diacetyl and 2,3-pentanedione from personal short-term sampling were 

higher for tasks involving flavoring, grinding roasted coffee beans, and weighing and 

packaging roasted coffee.

● Diacetyl, 2,3-pentanedione, or 2,3-hexanedione were measured in all instantaneous 

canister samples collected from grinding flavored coffee, flavoring coffee, and the 

headspace of the liquid flavoring.

● All tested roasted coffee beans emitted diacetyl or 2,3-pentanedione.

● Carbon monoxide levels were generally low throughout the facility but higher near 

grinding activity.

● Some employees reported eye, nose, or sinus symptoms. Some employees reported 

their symptoms were caused or aggravated by green beans, burlap bags, or by grinding 

or flavoring coffee.

● Some employees reported wheezing or whistling in the chest that was aggravated by 

green coffee beans.

● One spirometry test result indicated mild obstruction.

● The flavoring, grinding, and packaging processes presented risk factors for repetitive 

strain injuries and burns.

What the Employer Can Do

● Ensure employees understand potential hazards (e.g., diacetyl, 2,3-pentanedione, 

carbon monoxide, carbon dioxide, and green and roasted coffee dust) in the workplace 

and how to protect themselves.

● Follow manufacturer’s guidelines for periodic cleaning of the roasters’ exhausts.

● Limit access to the area while higher exposure tasks are occurring.

● Continue to cover bins of roasted coffee beans to reduce emissions of alpha-diketones, 

carbon monoxide, and carbon dioxide into the air. 

● Automate transfer of roasted beans, whenever possible, to minimize manual handling.

● Install local exhaust ventilation to reduce air concentrations of alpha-diketones during 

the following tasks: 1) flavoring coffee; 2) blending roasted coffee by hand, if an 

alternative method cannot be provided; 3) grinding roasted coffee; and 4) weighing and 

packaging roasted coffee. 

● Conduct follow-up air sampling to verify that the modifications have been effective in 

reducing exposures to below the recommended exposure limits.

● If follow-up air sampling after engineering controls have been installed 

and administrative controls are implemented indicates levels of diacetyl or 

2,3-pentanedione are above their respective National Institute for Occupational Safety 
Health Hazard Evaluation Report 2017-0020-3316 Page iii

and Health recommended exposure limit or short-term exposure limit, or if a long delay 

is anticipated before these controls can be put into place, we recommend respiratory 

protection be used during tasks with elevated exposures.

● Require lift gates for all deliveries of green beans.

● Eliminate the use of compressed air as much as possible during cleaning. Instead, use 

a vacuum system with a high-efficiency particle air filter and wet methods whenever 

possible. 

● Encourage employees to report new, worsening, or ongoing respiratory symptoms to 

their personal healthcare providers and to a designated individual at the workplace.

● Institute a medical monitoring program for employees who work in the production area.

What Employees Can Do

● Whenever possible, avoid spending time in the immediate area during flavoring, 

grinding, and packaging.

● As much as possible, avoid placing your head directly above or inside roasted bean 

storage bins. 

● Use any local exhaust ventilation as instructed by your employer when it is installed. 

● Pour green beans into the roaster hopper from the control panel side of the roaster to 

help prevent the possibility of contact with the hot roaster exhaust duct.

● Report new, persistent, or worsening respiratory symptoms to your personal healthcare 

provider(s) and a designated individual at your workplace.

● Participate in any personal air sampling offered by your employer.

● Participate in your employer’s medical monitoring program as instructed by your 

employer.
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Health Hazard Evaluation Report 2017-0020-3316 Page v

Abbreviations

μg Microgram

°F degrees Fahrenheit

ACGIH® American Conference of Governmental Industrial Hygienists

APF Assigned protection factor

AX Area of reactance

CFR Code of Federal Regulations

CO Carbon monoxide

CO2 Carbon dioxide

COPD Chronic obstructive pulmonary disease

DR5-R20 The difference between resistance at 5 and 20 Hertz

FEV1 1-second forced expiratory volume

Fres Resonant frequency

FVC Forced vital capacity

kPa/(L/s) Kilopascals per liter per second

IDLH Immediately dangerous to life or health

LOD Limit of detection

mL Milliliter

mL/min Milliliter per minute

NHANES National Health and Nutrition Examination Survey

NIOSH National Institute for Occupational Safety and Health

OEL Occupational exposure limit

OSHA Occupational Safety and Health Administration

PEL Permissible exposure limit

ppb Parts per billion

ppm Parts per million

R5 Resistance at 5 Hertz

R20 Resistance at 20 Hertz

REL Recommended exposure limit

RH Relative humidity

STEL Short-term exposure limit

TLV® Threshold limit value

TVOC Total volatile organic compounds

TWA Time-weighted average

VOC Volatile organic compound

X5 Reactance at 5 Hertz
Health Hazard Evaluation Report 2017-0020-3316 Page 1

Summary

In November 2016, the Health Hazard Evaluation Program of the National Institute for 

Occupational Safety and Health received a request from management of a coffee roasting 

and flavoring facility with six employees regarding repetitive motion injuries, potential 

burns, general warehouse safety, and potential employee exposure to green coffee bean dust, 

diacetyl, and 2,3-pentanedione during coffee processing. In January 2017, we observed work 

practices and conducted an industrial hygiene survey and a medical survey at the facility. The 

industrial hygiene survey consisted of collecting personal breathing zone and area air samples 

for alpha-diketones (i.e., diacetyl, 2,3-pentanedione, and 2,3-hexanedione), carbon monoxide, 

and carbon dioxide. Bulk samples of whole bean coffee and flavoring were collected to 

evaluate the potential for emission of diacetyl, 2,3-pentanedione, and 2,3-hexanedione. We 

used continuous monitoring instruments to measure total volatile organic compounds, carbon 

monoxide, carbon dioxide, temperature, and relative humidity in specific areas and during 

tasks. The medical survey consisted of a health questionnaire and breathing tests. One interim 

report with recommendations was sent to the company following our visit. 

Overall, full-shift time-weighted average air concentrations of diacetyl and 2,3-pentanedione 

were higher in flavoring and grinding areas of the facility. All four of the personal full-shift 

samples collected in the production area exceeded the NIOSH recommended exposure limit 

for diacetyl of 5 parts per billion, with a maximum measured concentration of 20.7 parts per 

billion. One of the four personal full-shift samples collected in the production area exceeded 

the NIOSH recommended exposure limit for 2,3-pentanedione of 9.3 parts per billion, with 

a maximum measured concentration of 24.0 parts per billion. We identified some work tasks 

that resulted in relatively higher air concentrations of diacetyl than other tasks. Specifically, 

flavoring roasted coffee beans by hand, grinding flavored and unflavored roasted coffee 

beans, and weighing and packaging roasted coffee were associated with higher diacetyl 

levels. Some employees reported eye, nose, or sinus symptoms or wheezing or whistling 

in the chest that was aggravated at work. We also observed tasks that presented risk factors 

for repetitive strain injuries and burns, specifically the flavoring, grinding, and packaging 

processes. We recommend installing local exhaust ventilation, implementing administrative 

controls such as modification of work practices, and training employees about workplace 

hazards. We also recommend a medical monitoring program to identify any employees who 

might be developing work-related lung disease (e.g., asthma, obliterative bronchiolitis) and 

to help management prioritize interventions to prevent occupational lung disease. 
Page 2 Health Hazard Evaluation Report 2017-0020-3316

Introduction

In November 2016, the Health Hazard Evaluation Program of the National Institute for 

Occupational Safety and Health (NIOSH) received a request from management at a coffee 

roasting and flavoring facility. The request stated concerns about repetitive motion injuries, 

potential burns, general warehouse safety, and potential employee exposure to green coffee 

bean dust, diacetyl, and 2,3-pentanedione during coffee processing. In January 2017, we 

observed work practices and conducted an industrial hygiene survey and a medical survey 

at the facility. We collected personal and area breathing zone air samples for volatile 

organic compounds (VOCs), including diacetyl, 2,3-pentanedione, and 2,3-hexanedione. 

We also monitored carbon monoxide (CO), carbon dioxide (CO2), and total volatile organic 

compounds (TVOCs). The medical survey consisted of a health questionnaire and breathing 

tests. After the visit, we provided an interim report with recommendations.

Background

Diacetyl and 2,3-Pentanedione 

Diacetyl (2,3-butanedione) and 2,3-pentanedione (acetyl propionyl) are VOCs known as 

alpha-diketones that are added as ingredients in food flavorings used in some food products 

such as microwave popcorn, bakery mixes, and flavored coffee [Day et al. 2011; Kanwal et 

al. 2006; Bailey et al. 2015]. Diacetyl, 2,3-pentanedione, other VOCs, and gases such as CO 

and CO2 are naturally produced and released during the coffee roasting process [Duling et al. 

2016; Raffel and Thompson 2013; Daglia et al. 2007; Nishimura et al. 2003; Newton 2002]. 

Grinding roasted coffee beans produces a greater surface area for off-gassing (sometimes 

called degassing) of these compounds [Akiyama et al. 2003]. Often, coffee roasting facilities 

package newly roasted coffee in permeable bags or in bags fitted with one-way valves to 

allow the coffee to off-gas after it is packaged. Sometimes, newly roasted coffee is placed in 

bins or containers and allowed to off-gas before packaging. 

NIOSH has recommended exposure limits (RELs) for diacetyl and 2,3-pentanedione 

in workplace air (Table 1). The NIOSH objective in establishing RELs for diacetyl and 

2,3-pentanedione is to reduce the risk of respiratory impairment (decreased lung function) 

and the severe irreversible lung disease obliterative bronchiolitis associated with occupational 

exposure to these chemicals. The NIOSH RELs are intended to protect workers exposed to 

diacetyl or 2,3-pentanedione for a 45-year working lifetime. The REL for diacetyl is based on 

a quantitative risk assessment which necessarily contains assumptions and some uncertainty. 

Analytical limitations current at the time were taken into consideration in setting the REL for 

2,3-pentanedione. The RELs should be used as guidelines to indicate when steps should be 

taken to reduce exposures in the workplace.

These exposure limits and the accompanying recommendations for control of exposures were 

derived from a risk assessment of flavoring-exposed workers. At an exposure equal to the 

diacetyl REL, the risk of adverse health effects is low. NIOSH estimated that about 1 in 1,000 

workers exposed to diacetyl levels of 5 parts per billion (ppb) as a time-weighted average 
Health Hazard Evaluation Report 2017-0020-3316 Page 3

(TWA) for 8 hours a day, 40 hours a week for a 45-year working lifetime would develop 

reduced lung function (defined as forced expiratory volume in one second [FEV1] below the 

lower limit of normal) as a result of that exposure. NIOSH predicted that around 1 in 10,000 

workers exposed to diacetyl at 5 ppb for a 45-year working lifetime would develop more 

severe lung function reduction (FEV1 below 60% predicted, defined as moderately severe by 

the American Thoracic Society [Pellegrino et al. 2005]). Workers exposed for less time would 

be at lower risk for adverse lung effects.

2,3-Hexanedione

2,3-Hexanedione is also an alpha-diketone that is sometimes used as a substitute for diacetyl 

and is produced naturally during coffee roasting. In a study using animals, there was some 

evidence that 2,3-hexanedione might also damage the lungs, but it appeared to be less 

toxic than diacetyl and 2,3-pentanedione [Morgan et al. 2016]. There are no established 

occupational exposure limits for 2,3-hexanedione.

Carbon Monoxide and Carbon Dioxide

CO and CO2 are gases produced by combustion. They are also produced as a result of 

reactions that take place during coffee roasting. These gases are released during and after 

roasting and grinding in a process called off-gassing [Anderson et al. 2003]. High exposures 

to CO and CO2 can cause headache, dizziness, fatigue, nausea, altered mentation, rapid 

breathing, impaired consciousness, coma, and death [Newton 2002; Nishimura et al. 2003; 

Langford 2005; CDC 2013a; Raffel and Thompson 2013; Rose et al. 2017]. Occupational 

exposure limits for CO and CO2 are listed in Table 1.

Exposure Limits

We utilize mandatory (legally enforceable) and recommended occupational exposure limits 

(OELs) when evaluating workplace hazards. OELs have been developed by federal agencies 

and safety and health organizations to prevent adverse health effects from workplace 

exposures.

Occupational Safety and Health Administration (OSHA) [Mandatory]

The U.S. Department of Labor’s OSHA permissible exposure limits (PELs) are legal limits 

that are enforceable in workplaces covered under the Occupational Safety and Health Act. 

OSHA PELs represent the legal maximum for a TWA exposure to a physical or chemical 

agent over a work shift [OSHA 2016]. OSHA short-term exposure limits (STELs) are the 

legal maximum average exposure for a 15-minute time period. Some chemicals also have an 

OSHA ceiling value, which represent levels that must not be exceeded at any time. Currently, 

there are no PELs for diacetyl, 2,3-pentanedione, or 2,3-hexanedione. For substances for 

which an OSHA PEL has not been issued, violation of the OSHA General Duty Clause 

can be considered using available occupational exposure references and recommendations 

[OSHA 1993; OSHA 2003], such as the American Conference of Governmental Industrial 

Hygienists (ACGIH®) Threshold Limit Values (TLVs®) and NIOSH RELs.

American Conference of Governmental Industrial Hygienists (ACGIH) [Recommendations]

ACGIH is a professional, not-for-profit scientific association that reviews existing published, 
Page 4 Health Hazard Evaluation Report 2017-0020-3316

peer-reviewed scientific literature and publishes recommendations for levels of substances 

in air based on an 8-hour workday and 40-hour workweek. These recommendations are 

called TLVs [ACGIH 2017a]. ACGIH TLVs are not standards; they are health-based 

guidelines derived from scientific and toxicological information. ACGIH provides TLV-TWA 

guidelines that are levels that should not be exceeded during any 8-hour workday of a 40-

hour workweek. ACGIH also provides TLV-STEL guidelines which are 15-minute exposure 

levels that should not be exceeded during a workday. Exposures above the TLV-TWA but less 

than the TLV-STEL should be (1) less than 15 minutes, (2) occur no more than four times a 

day, and (3) be at least 60 minutes between exposures [ACGIH 2017a]. Additionally, ACGIH 

provides TLV-Ceiling values, which are levels that should not be exceeded at any time during 

a work shift. The ACGIH TLV-TWA for diacetyl is 10 ppb. The TLV-STEL for diacetyl is 20 

ppb. Currently, there is no TLV-TWA or TLV-STEL for 2,3-pentanedione. ACGIH has placed 

2,3-pentanedione on the 2017 list of Chemical Substances and Other Issues Under Study 

[ACGIH 2017b].

National Institute for Occupational Safety and Health (NIOSH) [Recommendations]

NIOSH provides RELs as TWA concentrations that should not be exceeded over an 8- or 

10-hour work shift, during a 40-hour workweek [NIOSH 2010]. RELs are intended to 

be protective over a 45-year working lifetime. NIOSH also provides STELs which are 

15-minute TWA exposures that should not be exceeded at any time during a workday 

[NIOSH 2010]. Some chemicals have ceiling values, which are concentrations that should 

not be exceeded at any time [NIOSH 2010]. For some chemicals, NIOSH has established an 

Immediately Dangerous to Life or Health (IDLH) value. An IDLH value is a concentration 

of an air contaminant that can cause death or immediate or delayed permanent adverse 

health effects, or prevent escape from such an environment. Currently, NIOSH has RELs 

and STELs for diacetyl and 2,3-pentanedione. NIOSH does not have a REL or a STEL 

for 2,3-hexanedione. NIOSH does not have ceiling limits or IDLH values for diacetyl, 

2,3-pentanedione, or 2,3-hexanedione. 

For diacetyl and 2,3-pentanedione, the NIOSH RELs are 5.0 ppb and 9.3 ppb, respectively, 

as a TWA for up to an 8-hour workday during a 40-hour workweek (Table 1). The NIOSH 

STELs are 25 ppb for diacetyl and 31 ppb for 2,3-pentanedione [NIOSH 2016]. The NIOSH 

exposure limits do not differentiate between natural and synthetic chemical origin of diacetyl 

or 2,3-pentanedione. Although the NIOSH exposure limit for 2,3-pentanedione is above 

that of diacetyl, 2,3-pentanedione has been shown to be as hazardous as diacetyl [Hubbs 

et al. 2012; Morgan et al. 2012]. The NIOSH REL is higher for 2,3-pentanedione than for 

diacetyl largely because analytic measures were not available in a validated OSHA method 

to detect 2,3-pentanedione at lower levels. The hazard potential probably increases when 

these chemicals occur in combination with each other; having exposure to chemicals with 

the same functional alpha-diketone group and effect on the same system or organ (e.g., 

lungs) can result in additive effects [ACGIH 2017a]. In addition to the REL, NIOSH also 

recommends an action level for diacetyl of 2.6 ppb to be used with exposure monitoring in an 

effort to ensure employee exposures are routinely below the diacetyl REL. When exposures 

exceed the action level, employers should take corrective action (i.e., determine the source of 

exposure, identify methods for controlling exposure) to ensure that exposures are maintained 
Health Hazard Evaluation Report 2017-0020-3316 Page 5

below the NIOSH REL for diacetyl [NIOSH 2016].

Table 1. Personal exposure limits for compounds sampled during the NIOSH survey, January 

2017.

OSHA* ACGIH NIOSH

Compound

PEL TLV STEL REL STEL IDLH

Diacetyl — 10 ppb 20 ppb 5.0 ppb† 25 ppb —

2,3-Pentanedione — — — 9.3 ppb† 31 ppb —

2,3-Hexanedione — — — — — —

Carbon dioxide‡ 5,000 ppm 5,000 ppm 30,000 ppm 5,000 ppm 30,000 ppm 40,000 ppm

Carbon 

monoxide‡ 50 ppm 25 ppm — 35 ppm 200 ppm 

(ceiling limit)§ 1,200 ppm

Note: OSHA=Occupational Safety and Health Administration; ACGIH=American Conference of 

Governmental Industrial Hygienists; NIOSH=National Institute for Occupational Safety and Health; 

PEL=permissible exposure limit; TLV=threshold limit value; STEL=short-term exposure limit; 

REL=recommended exposure limit; IDLH=immediately dangerous to life or health; ppb=parts per 

billion; ppm=parts per million; “—”=no exposure limit available.

*

There are no OSHA STELs for the compounds in the table.

†

The NIOSH RELs for diacetyl and 2,3-pentanedione are time-weighted averages for up to an 8-hour day, 

during a 40-hour workweek.

‡

OSHA and NIOSH limits are designed for occupational exposure measurements in manufacturing and 

other trades that have potential sources of carbon dioxide or carbon monoxide (e.g., coffee roasting, 

welding, vehicle exhaust, diesel engine exhaust). Typical levels of carbon monoxide in offices are 0–5 ppm. 

In office settings, carbon dioxide generally should not be greater than 700 ppm above outdoor carbon 

dioxide levels; this typically corresponds to indoor concentrations below 1,200 ppm.

§

This is the NIOSH ceiling exposure limit for carbon monoxide. A ceiling concentration should not be 

exceeded at any time.

Obliterative Bronchiolitis

Obliterative bronchiolitis is a serious, often disabling, lung disease that involves scarring of 

the very small airways (i.e., bronchioles). Symptoms of this disease might include cough, 

shortness of breath on exertion, or wheeze, that do not typically improve away from work 

[NIOSH 2012]. Occupational obliterative bronchiolitis has been identified in flavoring 

manufacturing workers and microwave popcorn workers who worked with flavoring 

chemicals or butter flavorings [Kreiss 2013; Kim et al. 2010; Kanwal et al. 2006]. It has 

also been identified in employees at a coffee roasting and packaging facility that produced 

unflavored and flavored coffee [CDC 2013b]. A NIOSH health hazard evaluation at that 

facility found diacetyl and 2,3-pentanedione concentrations in the air that were elevated 

and identified three sources: 1) flavoring chemicals added to roasted coffee beans in the 

flavoring area; 2) grinding unflavored roasted coffee beans and packaging unflavored ground 

and whole bean roasted coffee in a distinct area of the facility, and 3) storing roasted coffee 

in hoppers, on a mezzanine above the grinding/packaging process, to off-gas [Duling et al. 

2016]. At the time of the health hazard evaluation, workers had excess shortness of breath 

and obstruction on spirometry, both consistent with undiagnosed lung disease. Respiratory 

illness was associated with exposure and not limited to the flavoring areas [Bailey et al. 
Page 6 Health Hazard Evaluation Report 2017-0020-3316

2015]. However, all workers who were diagnosed with obliterative bronchiolitis had worked 

in the flavoring area. To date, no cases of obliterative bronchiolitis have been reported in 

workers at coffee roasting and packaging facilities that produce only unflavored coffee.

Work-related Asthma

Work-related asthma refers to asthma that is brought on by (“occupational asthma”) or made 

worse by (“work-exacerbated asthma” or “work-aggravated asthma”) workplace exposures 

[Tarlo 2016; Tarlo and Lemiere 2014; OSHA 2014; Henneberger et al. 2011]. It includes 

asthma due to sensitizers, which cause disease through immune (allergic) mechanisms, and 

asthma due to irritants, which cause disease through non-immune mechanisms. Symptoms of 

work-related asthma include episodic shortness of breath, cough, wheeze, and chest tightness. 

The symptoms might begin early in a work shift, towards the end of a shift, or hours after a 

shift. They generally, but do not always, improve or remit during periods away from work, 

such as on weekends or holidays. 

Green and roasted coffee dust and castor beans (from cross-contamination of bags used 

to transport coffee) are known risk factors for occupational asthma [Figley and Rawling 

1950; Karr et al. 1978; Zuskin et al. 1979, 1985; Thomas et al. 1991]. Persons who become 

sensitized (develop an immune reaction) to coffee dust can subsequently react to relatively 

low concentrations in the air. Others might experience irritant-type symptoms from exposure 

to coffee dust [Oldenburg et al. 2009].

Based on the findings of previous NIOSH health hazard evaluations regarding alphadiketones, the coffee roasting and flavoring company wanted to characterize concentrations 

of alpha-diketones in the facility. Because of concerns about repetitive motion injuries, 

potential burns, general warehouse safety, and respiratory health from alpha-diketones, in 

November 2016, the management submitted a health hazard evaluation request to NIOSH.

Process Description

Personnel

The coffee roasting and flavoring company employed six employees. During our visit, two 

employees worked production, two employees worked administrative, one employee worked 

deliveries, and one employee was on leave.

Facility

The coffee roasting and flavoring company was located in a single-story building with 

a production area and a conference/administration area. The facility was approximately 

1,300 square feet. The production area included the production office, cold brew storage, 

supply storage, roaster, flavoring, grinding and weigh/pack, and green bean storage. The 

facility roasted, ground, flavored, and packaged coffee for wholesale to local businesses 

and churches. Roasted beans were packaged either whole or ground and either flavored or 

unflavored, depending on the needs of the customer. 
Health Hazard Evaluation Report 2017-0020-3316 Page 7

Green Beans

The coffee roasting and flavoring facility received green coffee beans in burlap bags from 

Nicaragua, Brazil, Kenya, Costa Rica, Ethiopia, Colombia, and Tanzania. Bags of green 

coffee beans delivered to the facility were manually unloaded from delivery trucks. The 

green coffee beans were stored on pallets located next to the roaster.

Roasting

The roaster was turned on to begin heating to the desired roasting temperature. To prepare 

a batch of coffee beans for roasting, the roaster operator scooped the desired amount of 

coffee beans from a bag of green coffee beans into a five-gallon bucket. The green beans 

were then dumped into the hopper at the top of the roaster. The beans were heated to a 

specific temperature and time period for the desired roast. Time and temperature varied 

among different types of roasts. Once the beans were roasted for the desired amount of time, 

the roaster operator pulled a lever that allowed the roasted beans to drop into a cooling bin 

where they were agitated by a rotating arm. The cooling bin utilized a downdraft exhaust 

system that drew air over the roasted beans to accelerate cooling. The downdraft system 

exhausted through the roaster and then to the outside through a ventilation pipe. The roaster 

operator monitored the roasting equipment throughout the roasting and cooling process. After 

cooling, the roasted beans were dispensed from the cooling bin into 10-gallon plastic storage 

containers with lids. The roaster operator manually moved the plastic storage containers to a 

storage area located underneath the grinding bench approximately 15 feet away.

Flavoring

Approximately 12 quarts of roasted coffee beans were scooped into an 18-quart bucket for 

flavoring. The only flavoring used during our visit was a butterscotch flavor. The employee 

measured the desired amount of flavoring into a measuring cup. The flavoring was then 

poured over the roasted beans. A lid was put onto the 18-quart bucket, and the employee 

shook the bucket overhead for approximately 30 seconds to one minute to mix the flavoring.

Grinding

The majority of roasted coffee was ground. In the grinding area, roasted beans were 

poured from the plastic storage containers or flavoring mixing bucket into the tops of the 

grinders. The ground coffee was collected in a large plastic bag and stored for weighing 

and packaging. There were four grinding machines, one for flavored coffee and three for 

unflavored coffee.

Weighing and Packaging

Coffee was packaged into 4-ounce, 6-ounce, 5-pound, and 11-pound packages. For whole 

bean coffee, orders were filled by scooping roasted beans from the desired storage containers, 

weighing the beans on a scale, and then placing the beans into a bag and sealing the bag with 

a heat sealer. For ground coffee, orders were filled by scooping ground coffee from the large 

plastic bags in the grinding area, weighing the ground coffee on a scale, and then scooping 

the weighed coffee into a bag and sealing the bag with a heat sealer. Completed orders were 

stored on a bench top located next to the grinding area.
Page 8 Health Hazard Evaluation Report 2017-0020-3316

Cleaning Activities

An employee used a portable vacuum and air compressor to clean the roaster and remove 

accumulated chaff under the cooling bin. Then the employee would wipe the exterior of the 

roaster down with paper towels and water.

Cold-brew and Nitro Coffee

The facility would brew coffee and store cold-brew coffee in the production office/cold brew 

storage area. Nitro coffee was produced from cold brew by pressurizing the cold-brew coffee 

with nitrogen inside of a keg. The cold-brew coffee and nitro coffee were delivered to local 

churches and businesses.

Personal Protective Equipment

Employees were not required to wear a company uniform or protective clothing. We did not 

observe employees wearing respiratory protection for chemicals or dust during our visit; 

however, we observed N95 respirators available for voluntary use.

Methods

We visited the coffee roasting and flavoring facility in January 2017. We held an opening 

meeting with management and employees, observed work practices, collected bulk samples 

and air samples, and conducted a medical survey. At the conclusion of our site visit, we 

held a closing meeting with management and employees. We provided a letter detailing our 

evaluation and preliminary recommendations to management in February 2017. 

We had the following objectives for the health hazard evaluation:

1. Measure employees’ exposure to diacetyl, 2,3-pentanedione, and 2,3-hexanedione 

during coffee processing;

2. Identify process areas or work tasks associated with emissions of diacetyl, 

2,3-pentanedione, and 2,3-hexanedione;

3. Measure levels of CO and CO2 throughout the facility;

4. Determine prevalence of mucous membrane, respiratory, and systemic symptoms 

among employees and if those symptoms were work-related or aggravated by work;

5. Determine if employees had abnormal lung function tests; and

6. Evaluate ergonomic stressors and potential for burns by observing work practices and 

asking relevant open-ended questions.

Industrial Hygiene Survey

Sampling Times for Alpha-Diketones 

We designed the sampling strategy to assess full-shift exposures and to identify tasks 

and processes that were the greatest contributors to worker exposure to alpha-diketones. 

Sampling was conducted over two days during the site visit. For diacetyl, 2,3-pentanedione, 
Health Hazard Evaluation Report 2017-0020-3316 Page 9

and 2,3-hexanedione, air samples were collected over seconds, minutes, and hours. Samples 

collected over hours can help determine average concentrations that can be compared to the 

NIOSH RELs for diacetyl and 2,3-pentanedione. These average concentrations might not tell 

us about short-term peak exposures that could be relevant to respiratory health, particularly 

when tasks are repeated multiple times per day. Therefore, during particular tasks, we 

collected air samples over several minutes. We also conducted instantaneous sampling over 

seconds to help identify point sources of alpha-diketones. 

Employees that participated in air sampling were given the opportunity to request their 

individual air sampling results. 

Air Sampling and Analysis Using Modified Occupational Safety and Health Administration 

(OSHA) Methods 1013/1016

We collected personal and area air samples for diacetyl, 2,3-pentanedione, and 

2,3-hexanedione on silica gel sorbent tubes during the industrial hygiene survey over two 

days. The samples were collected and analyzed according to the modified OSHA sampling 

and analytical Methods 1013/1016 [OSHA 2008; OSHA 2010; LeBouf and Simmons 2017]. 

In accordance with the two methods, two glass silica gel sorbent tubes were connected by a 

piece of tubing and inserted into a protective, light-blocking cover. The tubes were connected 

in series to a sampling pump pulling air through the tubes at a flow rate of 50 milliliters 

per minute (mL/min). The sampling setup was attached to an employee’s breathing zone or 

placed in an area basket in various places throughout the facility. For full-shift sampling, we 

collected two consecutive 3-hour samples and calculated the TWA concentration from the 

two samples, assuming that the total 6-hour monitoring results reflected a full work shift (8-

hour) TWA exposure. Although this might introduce some error, it is a conservative approach 

that is more protective of employees than the alternative assumption of no exposure during 

the last two hours of the shift. We refer to these samples as “full-shift samples” throughout 

this report. We also collected short-term task based samples in the same manner, but the 

sampling pump flow rate was 200 mL/min as detailed in OSHA Methods 1013 and 1016 

[OSHA 2008; 2010]. Sampling times were dependent on the duration of the task being 

performed. 

Analyses of the samples were performed in the NIOSH Respiratory Health Division’s 

Organics Laboratory. The samples were extracted for one hour in 95% ethanol: 5% water 

containing 3-pentanone as an internal standard. Samples were analyzed using an Agilent 

7890/7001 gas chromatograph/mass spectrometer system operated in selected ion monitoring 

mode for increased sensitivity compared to the traditional flame ionization detector used in 

OSHA Methods 1013 and 1016 [LeBouf and Simmons 2017].

A limit of detection (LOD) is the lowest mass that an instrument can detect above 

background and is a criteria used to determine whether to report a result from a sample. 

LODs for the visit were 0.01 micrograms per sample (μg/sample) for diacetyl, 0.01 μg/

sample for 2,3-pentanedione, and 0.01 μg/sample for 2,3-hexanedione; these were based on 

the lowest mass used in the calibration curve. These equate to 0.32 ppb for diacetyl, 0.27 

ppb for 2,3-pentanedione, and 0.24 ppb for 2,3-hexanedione for a typical full-shift TWA air 
Page 10 Health Hazard Evaluation Report 2017-0020-3316

sample but will vary depending on the volume of air collected during the sampling period. 

The LODs for task samples are generally higher than typical LOD values for full-shift 

samples, because the air volumes collected during task samples are lower. When the values 

presented in the report are from samples below the LOD they are denoted by a “<” symbol. 

Air Sampling and Analysis Using Evacuated Canisters

We collected instantaneous source air samples for VOCs including diacetyl, 

2,3-pentanedione, and 2,3-hexanedione using evacuated canisters. We also collected 

instantaneous air samples before and after the work shift to determine if air concentrations of 

alpha-diketones increased over a work shift. The evacuated canister sampling setup consisted 

of a 450-milliliter (mL) evacuated canister equipped with an instantaneous flow controller 

that was designed for a short sampling duration (less than 30 seconds). Instantaneous samples 

were taken by opening the evacuated canister to grab a sample of air to help identify point 

sources of alpha-diketones. For source air samples, a NIOSH employee placed the inlet of the 

flow controller directly at the source of interest. 

The canister air samples were analyzed using a pre-concentrator/gas chromatograph/

mass spectrometer system pursuant to a published method validation study [LeBouf et al. 

2012], with the following modifications: the pre-concentrator was a Model 7200 (Entech 

Instruments, Inc., Simi Valley, CA) and included the compounds diacetyl, 2,3-pentanedione, 

2,3-hexanedione, acetaldehyde, acetone, acetonitrile, benzene, chloroform, d-limonene, 

ethanol, ethylbenzene, isopropyl alcohol, methyl methacrylate, methylene chloride, styrene, 

toluene, alpha-pinene, m,p-xylene, and o-xylene. At present, this canister method is partially 

validated [LeBouf et al. 2012] and not considered the standard method. LODs were 0.26 ppb 

for diacetyl, 0.36 ppb for 2,3-pentanedione, and 0.64 ppb for 2,3-hexanedione based on a 

three-times dilution factor, which is typical for restricted flow controller samplers. However, 

LODs are dependent on the pressure inside each canister after the samples have been 

collected, and they might be higher or lower than typical LOD values. 

Bulk Sampling and Headspace Analysis

We used 50-mL sterile polypropylene centrifuge tubes to collect approximately 40-mL 

bulk samples of roasted whole bean coffee and liquid flavoring. For headspace analysis of 

alpha-diketones, we transferred 1 gram of solid bulk material into a sealed 40-mL amber 

volatile organic analysis vial and let it rest for 24 hours at room temperature (70°F) in the 

laboratory. Then 2 mL of headspace air was transferred to a 450-mL canister and pressurized 

to approximately 1.5 times atmospheric pressure. Using the canister analysis system, 

the concentrations were calculated in ppb of analytes in the headspace as an indicator of 

emission potential.

Real-time Air Sampling

We used RAE Systems (San Jose, CA) ppbRAE 3000 (Model #PGM-7340) and Ion Science 

(Stafford, TX) Tiger Handheld VOC monitors to measure concentrations of TVOCs in the air. 

The TVOC monitors have a non-specific photoionization detector that responds to chemicals 

with ionization potentials below the energy of the lamp. This sampling was conducted to 

identify areas where coffee could be releasing TVOCs. Areas where higher concentrations of 
Health Hazard Evaluation Report 2017-0020-3316 Page 11

TVOCs are measured might benefit from further sampling to characterize specific exposures 

to alpha-diketones. We also collected real-time measurements of CO2, CO, temperature, and 

relative humidity (RH) using TSI Incorporated (Shoreview, MN) VelociCalc Model 9555-

X Multi-Function Ventilation Meters equipped with Model 982 IAQ probes. All real-time 

instruments were set to log data at 10-second intervals.

Personal Carbon Monoxide (CO) Sampling

Some employees wore Dräger (Lübeck, Germany) Pac 7000 personal single gas detectors 

to monitor personal CO exposures. Personal CO monitors were set to log data at 10-second 

intervals.

Repetitive Motion Injuries, Burns, and Safety Concerns

We evaluated the work environment and production tasks for ergonomics, burn potential, and 

general small warehouse safety issues by observing and documenting work practices.

NIOSH Medical Survey

Participants

We invited all current employees to participate in the medical survey at the workplace on 

January 12, 2017. Participation was voluntary; written informed consent was obtained from 

each participant before testing. The survey included, in the order performed, a medical and 

work history questionnaire, quantification of exhaled nitric oxide, impulse oscillometry, 

spirometry, and if indicated the administration of a bronchodilator with repeat impulse 

oscillometry and spirometry. We mailed participants their individual reports explaining their 

breathing test results and recommended each participant provide the information to their 

personal physician.

Questionnaire

We used an interviewer-administered computerized questionnaire to ascertain symptoms 

and diagnoses, work history at this coffee roasting and flavoring facility and other coffee or 

flavoring companies, and cigarette smoking history. Questions on respiratory health were 

derived from five standardized questionnaires, the European Community Respiratory Health 

Survey [Burney et al. 1994; ECRHS 2014], the American Thoracic Society adult respiratory 

questionnaire (ATS-DLD-78) [Ferris 1978], the International Union Against Tuberculosis 

and Lung Disease [Burney and Chinn 1987; Burney et al. 1989], and the Third National 

Health and Nutrition Examination Survey (NHANES III) [CDC 1996] and NHANES 2007-

2012 questionnaires [CDC 2017a]. Some of the questions appeared on more than one of 

the standardized questionnaires. We also supplemented our questionnaire with additional 

respiratory and systemic symptom questions and open-ended questions about concerns 

regarding repetitive motion injuries and burns.

Spirometry 

The purpose of the spirometry test was to determine a person’s ability to move air out of 

their lungs. Test results were compared to expected normal values. The test included three 

measurements or calculations: 1) forced vital capacity (FVC), (the total amount of air the 

participant can forcefully blow out after taking a deep breath), 2) FEV1 (the amount of air 
Page 12 Health Hazard Evaluation Report 2017-0020-3316

that the participant can blow out in the first second of exhaling), and 3) the ratio of FEV1 to 

FVC. We used American Thoracic Society criteria for acceptability and repeatability [Miller 

et al. 2005]. 

We used a volume spirometer (dry rolling seal spirometer) to measure exhaled air volume 

and flow rates. We used equations for predicted values and lower limits of normal derived 

from NHANES III data to define abnormal spirometry [Hankinson et al. 1999]. We defined 

obstruction as an FEV1/ FVC ratio less than the lower limit of normal with FEV1 less than the 

lower limit of normal; restriction as a normal FEV1/FVC ratio with FVC less than the lower 

limit of normal; and mixed obstruction and restriction as having FEV1, FVC, and FEV1/FVC 

ratio all less than the lower limit of normal. We used the FEV1 percent predicted to categorize 

such abnormalities as mild, moderate, moderately severe, severe, or very severe [Pellegrino 

et al. 2005].

Impulse Oscillometry

Many occupational lung diseases (e.g., chronic obstructive pulmonary disease (COPD), 

asthma) involve the small airways; however, this part of the lung is difficult to evaluate noninvasively. Oscillometry is a helpful technology to understand the effects of occupational 

exposures on the small airways. There are no contraindications to the test as this test is 

conducted using regular breathing and does not require a forceful exhalation [Smith et al. 

2005]. Spirometry can be normal despite respiratory symptoms or evidence of small airways 

disease on lung biopsy [King et al. 2011; Oppenheimer et al. 2007]; therefore, oscillometry 

results complement spirometry and can be used when spirometry is not possible because of a 

contraindication.

We used an impulse oscillometry machine (CareFusion Corp., San Diego, CA) to measure 

resistance (R), the energy required to propagate the pressure wave through the airways, 

and reactance (X), which reflects the viscoelastic properties of the respiratory system. The 

impulse oscillometry testing machine sends sound waves called pressure oscillations at 

different frequencies (e.g., 5 Hertz and 20 Hertz) into the airways to measure how airways 

respond to these small pressures. The test calculates 1) the airway resistance at different 

frequencies including 5 Hertz (R5) and 20 Hertz (R20), and the difference between R5 

and R20 (DR5-R20); 2) the reactance at different frequencies including 5 Hertz (X5); 3) 

resonant frequency (Fres) which is the frequency where there is no airway reactance; and 

4) the total reactance (AX) at all frequencies between 5 Hertz and the Fres. The predicted 

values for R and X were based on sex and age according to reference values recommended 

by the manufacturer [Vogel and Smidt 1994]. R5 was considered abnormal (elevated) if 

the measured value was equal to or greater than 140 percent of the predicted R5. X5 was 

considered abnormal (decreased) if the value of the predicted X5 minus measured X5 was 

equal to or greater than 0.15 kilopascals per liter per second (kPa/(L/s)). DR5-R20 values 

greater than 30% were considered abnormal and evidence of frequency dependence [Smith 

2015]. We interpreted the test as normal if both the R5 and X5 were normal [Smith 2015]. 

We defined possible large (central) airways abnormality as a normal X5 and elevated R5 

with no evidence of frequency dependence. We defined a possible small airways abnormality 

if there was evidence of frequency dependence and/or a decreased X5 with or without an 
Health Hazard Evaluation Report 2017-0020-3316 Page 13

elevated R5. We defined possible combined small (peripheral) and large (central airways) 

abnormality as a decreased X5 and elevated R5 with no evidence of frequency dependence.

Bronchodilator Reversibility Testing for Impulse Oscillometry and Spirometry

If a participant had abnormal impulse oscillometry or spirometry, we offered a bronchodilator 

inhaler medication (i.e., albuterol), which can open the airways in some individuals (e.g., 

asthmatics) and then repeated both tests after the participant received the bronchodilator. For 

oscillometry, we defined reversibility (improvement) after bronchodilator administration as a 

decrease of at least 20% of either Fres or R5 or a decrease of 40% for AX. For spirometry, we 

defined reversibility (improvement) as increases of at least 12% and 200 mL for either FEV1

or FVC after bronchodilator administration.

Fractional Exhaled Nitric Oxide (FeNO) 

We used the NIOX MINO® device (Aerocrine Inc., Morrisville, NC) to measure the amount 

of nitric oxide in the air the participant breathed out. Nitric oxide is a gas that is produced by 

the airways, and elevated levels can be a sign of eosinophilic airway inflammation in asthma 

[Dweik et al. 2011]. In adults, fractional nitric oxide concentration in exhaled breath levels 

above 50 ppb are considered elevated. In adults with asthma, elevated levels might indicate 

that their asthma is uncontrolled [Dweik et al. 2011].

Statistical Analysis 

We performed analyses using Excel (Microsoft®, Redmond, WA) and SAS version 9.4 (SAS 

Institute, Cary, NC). We created summary statistics by work area location and task. When the 

values presented in the report are from samples below the LOD they are denoted by a “<” 

symbol.

Results 

Industrial Hygiene Survey Results

Personal and Area Full-shift Air Sampling Results

Table A1 presents the personal and area full-shift air sampling results from our visit in 

January 2017. We collected five personal full-shift air samples, including four on employees 

working indoors and one on an employee performing off-site work, and 20 area full-shift 

air samples over two days. All four personal air samples collected indoors were above the 

NIOSH REL for diacetyl of 5.0 ppb, and one personal air sample was above the NIOSH REL 

for 2,3-pentanedione of 9.3 ppb. The samples exceeding the REL for diacetyl were collected 

on different days. Only one personal sample was above the LOD for 2,3-hexanedione. 

For area full-shift air sampling, the grinding area had the highest air concentrations of 

diacetyl with a range of 12.6 ppb–27.7 ppb. For grinding, the range was 12.1 ppb–28.0 ppb 

for 2,3-pentanedione and <0.2 ppb–0.7 ppb for 2,3-hexanedione. The roasting area had the 

second highest air concentration of diacetyl with a range of 5.4 ppb–12.6 ppb. For roasting, 

the range was 4.9 ppb–11.1 ppb for 2,3-pentanedione and <0.2 ppb for 2,3-hexanedione.
Page 14 Health Hazard Evaluation Report 2017-0020-3316

Task-based Air Sampling Results

Table A2 presents the personal task-based air sampling results from our visit in January 

2017. We collected 15 personal task-based air samples. An employee who flavored roasted 

beans for six minutes had an exposure to diacetyl of 67.2 ppb and 2,3-pentanedione of 82.6 

ppb. An employee who packaged ground coffee for 12 minutes had an exposure to diacetyl 

of 53.2 ppb and to 2,3-pentanedione of 56.8 ppb. An employee who ground coffee for 11 

minutes had an exposure to diacetyl of 32.0 ppb and to 2,3-pentanedione of 36.4 ppb. Just 

three of the task-based samples were above the LOD for 2,3-hexanedione, with a maximum 

concentration of 2.0 ppb.

Source Air Sampling Results

Table A3 presents the source air sampling results using instantaneous evacuated canisters.

We sampled at the top of a mixing bucket that contained whole bean coffee with butterscotch 

flavoring and measured 27.5 ppb for diacetyl, 68.6 ppb for 2,3-pentanedione, and <9.6 ppb 

for 2,3-hexanedione. We captured two instantaneous evacuated canister source samples 

during grinding of butterscotch-flavored coffee and found air concentrations of 65.5 ppb and 

489 ppb for diacetyl, 61.9 ppb and 604 ppb for 2,3-pentanedione, and 1.9 ppb and 13.7 ppb 

for 2,3-hexanedione. A sample was taken at the headspace of the butterscotch flavoring bottle 

that measured <3.8 ppb diacetyl, 1,469 ppb 2,3-pentanedione, and <9.4 ppb 2,3-hexanedione. 

Background Pre- and Post-shift Diacetyl and 2,3-Pentanedione Canister Results

Table A4 presents the results of the instantaneous evacuated canister pre- and postshift background air samples collected in the administration area, production office, and 

production area during our visit. Both diacetyl and 2,3-pentanedione air concentrations 

increased over the course of the work day. For the production area, the pre-shift diacetyl 

concentration was 7.1 ppb, and post-shift air concentration was 21.3 ppb; the pre-shift 

2,3-pentanedione air concentration was 5.7 ppb, and post-shift air concentration was 24.7 

ppb. The pre- and post-shift levels of 2,3-hexanedione were less than 1 ppb, with the 

exception of the Production Office post-shift sample that was 5.9 ppb.

Bulk Samples and Headspace Results

Table A5 presents the bulk sample results using headspace analysis. Air concentrations 

of diacetyl ranged from 1,384 ppb to 7,013 ppb for whole bean coffee. Air concentrations 

of 2,3-pentanedione ranged from 1,526 ppb to 8,014 ppb for whole bean coffee. The bulk 

samples for whole bean coffee were collected from the roaster cooling bin immediately after 

the beans were released from the roaster hopper or from whole bean coffee storage bins. The 

bulk sample of liquid flavoring had an air concentration of below the LOD for diacetyl and 

6,866 ppb for 2,3-pentanedione. Air concentrations from collected bulk samples were below 

the LOD for 2,3-hexanedione.

Real-time Monitoring: Carbon Dioxide (CO2), Carbon Monoxide (CO), Temperature, and 

Relative Humidity (RH)

Table A6 presents the results from real-time monitoring for CO2, CO, temperature, and RH 

collected during our visit. Average CO2 levels within the facility ranged from 928 parts per 

million (ppm) to 1,217 ppm. Average indoor CO levels ranged from 0.2 ppm to 3.8 ppm. 
Health Hazard Evaluation Report 2017-0020-3316 Page 15

Average indoor temperature levels ranged from 74.6 degrees Fahrenheit (°F) to 84.3°F. 

Average indoor RH levels ranged from 20.8% to 32.7%.

Real-time Monitoring: Total Volatile Organic Compounds (TVOC)

Table A7 presents the results from real-time monitoring for TVOCs during our visit. TVOC 

levels within the facility ranged from <0.1 ppb to 11,907 ppb. The flavoring area of the 

facility had the highest levels of TVOCs. During TVOC monitoring in the flavoring area, 

peak TVOC levels occurred when an employee was flavoring coffee.

Personal CO Sampling

Table A8 presents the results from real-time personal monitoring for CO. Four personal CO 

measurements were collected during our visit. CO minimum and maximum levels ranged 

from <0.1 ppm to 157 ppm. Average CO levels ranged from 1.6 ppm to 2.7 ppm over the 

course of the workday. Figure B1 presents CO levels for an employee during flavoring whole 

bean coffee and grinding flavored coffee.

Repetitive Motion Tasks, Burn Hazards, and Safety Observations

We observed employees manually transferring 70-kilogram bags of green beans from a 

delivery truck bed to a pallet on a pallet jack. We observed the employee pull the bag to their 

chest at the edge of the truck and then roll it off into their arms before twisting around to 

drop the bag onto the pallet. The delivery truck did not have a lift gate to aid in this process. 

Employees reported that some deliveries came on trucks with lift gates, although the weekly 

shipment of 11 bags that we observed never had a lift gate on the truck.

Employees scooped green beans out of 70-kilogram bags into small buckets. The roaster 

held a maximum of 26 pounds of green beans per roasting session. On average, employees 

scooped approximately 12 scoops of green beans to fill the bucket with 26 pounds of beans. 

Employees reported there would be a maximum of 13 roasts in a single day (approximately 

four per hour). After filling the bucket, beans were dumped into the roaster. Employees were 

observed performing this task on their tiptoes with their arms extended up over their heads. 

Some employees stood next to the hot exhaust duct of the roaster when pouring green beans 

into the roaster. Other employees poured the green beans into the roaster from the control 

panel side of the roaster.

Beans in the roaster weighed approximately 22 pounds after roasting. Employees were 

observed shaking flavoring buckets containing roasted beans in order to coat them with 

flavoring, with the bucket above shoulder height. Employees were also observed reaching 

over their heads to pour the beans into the grinders. We noted that sometimes during the 

grinding task, the grinders were located near the back of the packaging table, which required 

the employee to reach further than ideal to operate the grinder. Packaging whole beans or 

ground coffee required many repetitive motions. Employees needed to bend over to scoop 

whole beans from buckets on the floor. Ground coffee was scooped from larger bags on the 

work surface into varying sized packages. After packaging, the bags were heat sealed with a 

foot-operated crimping device, creating a potential burn hazard.
Page 16 Health Hazard Evaluation Report 2017-0020-3316

Regarding small warehouse safety issues, we observed a small rolling table near the roaster 

control panel that could block the roaster’s emergency stop button. We also observed 

employees placing their hands inside the roaster, and it was reported that in-depth cleaning of 

the roaster requires employees to have hands and arms inside the roaster.

Medical Survey Results 

Four of the five employees present on the day of the medical survey completed the medical 

questionnaire and breathing tests. All four participants reported working in or entering the 

production area, ranging from two hours to 38 hours per week. All reported being within 

an arm’s length of roasted coffee in one or more areas of the production process as well as 

being within an arm’s length of the container when flavoring was being added or mixed with 

roasted coffee.

Respiratory Symptoms, Repetitive Motion Tasks, and Burn Hazards

Some participants reported respiratory symptoms or eye, nose, or sinus symptoms that were 

caused or aggravated by green beans, burlap bags, or by grinding or flavoring coffee. Some 

employees reported wheezing or whistling in the chest that was aggravated by green coffee 

beans. When asked if there were any concerns about repetitive motion injuries at work, some 

employees mentioned scooping coffee and lifting buckets of green coffee beans to dump into 

the roaster hopper as potential sources of ergonomic strain. When asked if there were any 

concerns about burns at work, some employees mentioned the roaster and heat sealers as 

potential sources of burns, although no known burns had occurred.

Medical Tests

One spirometry test result indicated mild obstruction. Oscillometry and FeNO test results 

were normal. Because of the small number of participants and the need to protect individuals’

privacy, we cannot provide detailed results or shed light on possible work-relatedness, such 

as health measures by job title or task. We mailed each participant their individual lung 

function test results with an explanation of the results and recommended each participant 

provide the information to their personal physician.

Discussion

Diacetyl, 2,3-pentanedione, 2,3-hexanedione, other VOCs, and other chemicals such as CO 

and CO2 are naturally produced when coffee beans are roasted, and grinding the roasted 

coffee beans produces greater surface area for the off-gassing of these chemicals [Anderson 

et al. 2003; Akiyama et al. 2003; Daglia et al. 2007; Newton 2002; Nishimura et al. 2003; 

Raffel and Thompson 2013]. In addition, flavorings added to coffee can contain diacetyl or 

2,3-pentanedione. Occupational exposure to diacetyl and 2,3-pentanedione can cause loss of 

lung function and the lung disease obliterative bronchiolitis [NIOSH 2016]. 

Alpha-Diketones

Personal Air Sampling 

Four personal full-shift air samples taken inside the production area of the facility using 
Health Hazard Evaluation Report 2017-0020-3316 Page 17

standard OSHA methods were above the NIOSH REL for diacetyl. The highest personal 

full-shift exposure to diacetyl was 20.7 ppb collected from a production area employee 

during the site visit. One personal full-shift air sample taken inside the facility using standard 

OSHA methods was above the NIOSH REL for 2,3-pentanedione and measured at 24.0 

ppb. As described in the quantitative risk assessment from the NIOSH Criteria Document 

(Tables 5-27 and 5-34) [NIOSH 2016], after a 45-year working lifetime exposure to 10 ppb 

(a concentration lower than the highest concentration measured at this facility), NIOSH 

estimated about 3 in 1,000 workers would develop reduced lung function (FEV1 below the 

lower limit of normal). NIOSH predicted that around 2 in 10,000 workers exposed to diacetyl 

at 10 ppb would develop more severe lung function reduction (FEV1 below 60% predicted, 

defined as at least moderately severe by the American Thoracic Society [Pellegrino et al. 

2005]). After a 45-year working lifetime exposure to 20 ppb (a concentration closer to the 

highest concentration measured at this facility), NIOSH estimated that about 5 in 1,000 

workers would develop reduced lung function (FEV1 below the lower limit of normal). 

NIOSH predicted that 5 in 10,000 workers exposed to diacetyl at 20 ppb would develop 

more severe lung function reduction. NIOSH recommends keeping diacetyl concentrations 

below 5 ppb, because at this level the risk of reduced lung function after a working lifetime 

of exposure is below 1 in 1,000 workers. NIOSH recommends taking steps to reduce diacetyl 

exposures to below the REL of 5 ppb whenever possible.

During our visit, the roaster operator often remained at the roaster control panel during the 

roasting process. The roasting drum was fully enclosed, and air was exhausted through the 

roaster exhaust, minimizing exposures indoors. The only time the roasting drum was opened 

was during the transfer of roasted beans into the cooling drum. The downdraft system 

on the roaster machine pulled air over the roasted beans and down into the cooling drum 

to accelerate cooling, which might have decreased the roaster operator’s exposure while 

performing this task. 

Area Air Sampling 

Area full-shift samples (Table A1) collected from the grinding area had the highest 

concentrations of diacetyl (27.7 ppb) and 2,3-pentanedione (28.0 ppb), likely because 

grinding roasted coffee beans produces greater surface area for off-gassing of these chemicals 

[Anderson et al. 2003; Akiyama et al. 2003; Daglia et al. 2007; Newton 2002; Nishimura 

et al. 2003; Raffel and Thompson 2013]. The flavoring area air samples collected ranged 

from 10.0 ppb to 12.1 ppb for diacetyl and 9.7 ppb to 11.0 ppb for 2,3-pentanedione. The 

roasting area air samples ranged from 5.4 ppb to 12.6 ppb for diacetyl and 4.9 ppb to 11.1 

ppb for 2,3-pentanedione. Levels of diacetyl and 2,3-pentandione present in the flavoring and 

roasting areas of the facility are likely a result of the flavoring liquid, freshly roasted coffee, 

and grinding coffee. The area air samples collected from the administration area were the 

lowest in the facility and ranged from 1.8 ppb to 2.0 ppb for diacetyl and from 1.7 ppb to 2.1 

ppb for 2,3-pentanedione, indicating little entrainment of air from the production area into 

the administrative area.

During our visit, we also observed maximum recorded levels of CO at 78.9 ppm and CO2 at 

2,015 ppm at the grinding area (Table A6). However, CO and CO2 TWAs at the grinding area 
Page 18 Health Hazard Evaluation Report 2017-0020-3316

and throughout the facility did not exceed OELs. 

Task-based Exposures

Coffee processing involves multiple tasks that can cause intermittent, elevated exposures 

to diacetyl and 2,3-pentanedione. Traditional full-shift sampling will not characterize these 

short-term, peak exposures. Evaluating intermittent and task-based exposures to diacetyl 

and 2,3-pentanedione is difficult with current validated sampling methods (OSHA Methods 

1013/1016). Because tasks are sporadic in coffee processing, with some only lasting a few 

seconds or minutes, we used instantaneous evacuated canisters to sample tasks that were only 

a few seconds to minutes long and OSHA Methods 1013/1016 for longer duration tasks. We 

sampled by task, with varying durations, to understand which tasks might have contributed to 

higher exposures to diacetyl and 2,3-pentanedione. 

Our task-based air sampling revealed that some tasks had higher air concentrations of 

diacetyl or 2,3-pentanedione than other tasks. Employees would often flavor the roasted 

coffee beans in an 18-quart bucket and shake the bucket by hand. Using OSHA Methods 

1013/1016, we found flavoring coffee tasks resulted in air concentrations ranging from 22.7 

ppb to 67.2 ppb for diacetyl and 24.2 ppb to 82.6 ppb for 2,3-pentanedione (Table A2). Using 

instantaneous evacuated canisters, we also measured 27.5 ppb of diacetyl and 68.6 ppb of 

2,3-pentanedione during flavoring by hand (Table A3). Standing over the flavoring bucket 

while pouring the flavoring and manually shaking the container likely contributed to higher 

measured alpha-diketones for an employee performing this flavoring task. 

Employees would also grind flavored coffee, which likely additionally contributed to higher 

measured alpha-diketones. Using instantaneous evacuated canisters, we observed that 

grinding butterscotch-flavored coffee resulted in the highest instantaneous diacetyl (489 ppb) 

and 2,3-pentanedione (604 ppb) air concentrations (Table A3). Because these instantaneous 

samples were collected at the grinder discharge, they were not necessarily reflective of 

employee exposure; however, they indicate a source of alpha-diketones during grinding that 

could be controlled. These peak exposures to diacetyl and 2,3-pentanedione during flavoring 

and grinding tasks likely contributed to the higher personal full-shift air sample results for the 

production area employees.

Bulk Samples

Diacetyl is not found in green beans and forms later in the coffee roasting process [Daglia et 

al. 2007]. As expected, we found that roasted coffee emits alpha-diketones into the headspace 

of sealed vessels, indicating that roasted coffee is a considerable source of alpha-diketones 

in the facility. Bulk samples of roasted whole bean coffee resulted in the highest levels of 

alpha-diketones from headspace analysis (diacetyl 7,013 ppb and 2,3-pentanedione 8,014 

ppb). We also do not know how long the beans were in the storage bins prior to collecting the 

samples, but generally the time between roasting and packaging is on the order of hours to 

days. The amount of time roasted beans had off-gassed could be responsible for differences 

in headspace analysis results. 
Health Hazard Evaluation Report 2017-0020-3316 Page 19

Ventilation 

There was no general ventilation system present in the facility. The bay door was sometimes 

open during production activities, and this open bay door was the only source of fresh air 

entering the production area of the building. Installing local exhaust ventilation systems and a 

dilution ventilation system would help control the airborne concentrations of alpha-diketones.

Local Exhaust Ventilation

Local exhaust ventilation systems capture contaminants when generated and exhausts them 

before inhalation by employees occurs. Local exhaust ventilation systems generally consist 

of hoods or enclosures, duct work, or fans. Depending on the contaminant and whether air 

is recirculated, filters or other air cleaning technologies can be incorporated. When properly 

designed local exhaust ventilation systems are installed, overall workplace exposure levels 

can be reduced by removing contaminants at the source.

During our visit, we discussed some simple local exhaust ventilation systems that could 

be installed in the production space that would likely help reduce overall alpha-diketone 

exposures in the production space. Elevated concentrations of alpha-diketones were 

associated with grinding and flavoring activities. Installing localized air capture hoods, 

or even enclosing hoods, to isolate those processes and remove contaminants before they 

spread throughout the facility could substantially reduce overall employee exposures. Some 

consideration should be given to moving those activities closer together and near an exterior 

wall, which could make the local exhaust system more compact and inexpensive. 

General Exhaust or Dilution Ventilation

An adequate supply of outdoor air, typically delivered through a heating, ventilation, 

and air-conditioning system, is necessary in any occupied space to dilute pollutants that 

are released by equipment, processes, products, and people. In an ideal environment, 

good general ventilation provides fresh air into the space and removes contaminated air. 

General exhaust ventilation allows contaminants to be emitted into the workplace and then 

dilutes the concentration of the contaminant to acceptable levels. This is generally done by 

providing fresh outdoor air (or recirculated, filtered air) to the space to provide dilution. 

Simultaneously, air is exhausted from the space to remove the contaminants.

Installing a small air-handling unit that could provide some constant outdoor air flow would 

provide more dilution and removal of airborne contaminants from the space. Depending on 

the system chosen, it could also serve to help heat and/or cool the space throughout the year. 

It would also allow production operations to occur with the large bay door closed at all times. 

Regardless of how it is done, consistently supplying the production space with appropriate 

fresh, outdoor air will help reduce airborne contaminants, but it might still not bring all 

personal exposures to diacetyl and 2,3-pentanedione below the NIOSH RELs. Installing a 

dilution ventilation system in conjunction with effective local exhaust ventilation systems 

would be even more effective.

All decisions on ventilation upgrades should be made as part of an overall plan to improve 

engineering controls at the facility. A ventilation system expert can help meet all ventilation 
Page 20 Health Hazard Evaluation Report 2017-0020-3316

requirements in the production space and other areas of the building occupied by employees.

Repetitive Motion Injuries, Burns, and Safety

Many of the observed tasks presented risk factors for repetitive strain injuries. Changes to the 

physical work environment and operating procedures would reduce the strain on the body, 

reduce the risk of burns, and improve small warehouse safety.

We observed opportunities to improve the ergonomics of certain tasks while working 

with green beans, during the grinding and flavoring of roasted coffee beans, and regarding 

storage of items in the supply storage area. Because deliveries of green beans were manually 

unloaded from trucks at the bay door, to reduce ergonomic strain during this unloading task, 

we recommend using lift gates for all green bean deliveries and using two employees when 

moving bags of green beans. Pulling the grinders forward would reduce the need to reach 

to the back of the table while operating the grinder. During the flavoring task, the 18-quart 

bucket was held above shoulder height and shaken to mix the flavoring with the coffee beans. 

To reduce strain on the body, hands should be kept below shoulder level during the flavoring 

task. 

We also observed two areas, specifically the roaster’s exhaust duct and the heat sealers, 

where employees might be at risk for burns. To help prevent potential burns from the roaster 

exhaust duct, the green beans should be poured into the roaster hopper from the control panel 

side of the roaster. Similarly, turning off heat sealers after use will help prevent accidental 

burns.

To improve small warehouse safety, we recommend ensuring the small rolling table near 

the roaster is not blocking the roaster’s emergency stop button. To help avoid potentially 

hazardous conditions around the roaster, we recommend placing a lock on the roaster control 

panel and following OSHA’s control of hazardous energy (lockout/tagout) standard 29 CFR 

1910.147.

Medical Survey 

Among the employees who participated in the medical survey, mucous membrane symptoms, 

specifically eye, nose, and sinus symptoms, were the most commonly reported symptoms. 

Some employees reported their symptoms were caused or aggravated by green coffee 

beans, burlap bags, or by grinding or flavoring coffee. Coffee dust is an organic dust, and 

exposure to coffee dust is known to cause respiratory symptoms and is a known risk factor 

for occupational asthma [Karr et al. 1978; Zuskin et al. 1979, 1985, 1993; Thomas et al. 

1991; Sakwari et al. 2013]. Green coffee dust is thought to be a more potent allergen than 

roasted coffee dust because roasting destroys some of the allergenic activity [Lehrer et al. 

1978]. As discussed in the recommendation section, one way to prevent symptoms related to 

green coffee dust and burlap might be to make N95 disposable filtering-face piece respirators 

available for voluntary use when working with burlap bags of green beans. However, 

because N95s are not protective against alpha-diketones (diacetyl, 2,3-pentanedione, 

or 2,3-hexanedione), NIOSH-certified organic vapor cartridges would be warranted for 

flavoring.
Health Hazard Evaluation Report 2017-0020-3316 Page 21

Some employees reported upper and lower respiratory symptoms. Upper respiratory disease 

such as allergic rhinitis (hay fever, nasal allergies) and sinusitis are sometimes associated 

with lower respiratory symptoms and asthma and might precede the diagnosis of asthma 

[Shaaban et al. 2008; EAACI Task Force on Occupational Rhinitis et al. 2008; Rondón et 

al. 2012, 2017; Sahay et al. 2016]. Upper respiratory involvement (e.g., rhinitis, sinusitis) 

can result in suboptimal control of asthma. Asthma symptoms often improve when away 

from exposures that trigger symptoms while other lung diseases such as obliterative 

bronchiolitis or COPD generally do not improve. Spirometry can be used to help detect and 

follow individuals with asthma and other lung diseases such as obliterative bronchiolitis 

or COPD. Spirometry can show if air is exhaled from the lungs more slowly than normal 

(i.e., obstructive abnormality) or if the amount of air exhaled is smaller than normal (i.e., 

restrictive abnormality). In asthma, there is intermittent airways obstruction which is 

reversible after treatment with bronchodilator medications (e.g., albuterol). In obliterative 

bronchiolitis, scar tissue prevents the small airways (bronchioles) from opening up when 

albuterol is given. In other words, the airways are fixed and not responsive (reversible) to 

bronchodilator medicine. The obstructed airways prevent rapid emptying of the lung air 

sacs (alveoli) during exhalation. This explains why the respiratory symptoms of those with 

occupational obliterative bronchiolitis do not tend to improve when away from work-related 

exposures; however, avoidance of further exposure can stop progression of the disease 

[Akpinar-Elci et al. 2004].

Spirometry and impulse oscillometry measure different things. Spirometry assesses 

airflow and is the breathing test typically used to screen for flavoring-related lung disease. 

Impulse oscillometry assesses the airways response to a sound or pressure wave and has 

not commonly been used to screen for flavoring-related lung disease. In general, during 

the impulse oscillometry test, a small pressure impulse (sound wave) is imposed upon the 

inspiratory and expiratory airflow during normal tidal breathing. This pressure wave causes 

a disturbance in the airflow and pressure, and the response of the airways (i.e., change in 

pressure to change in flow) is a measure of the resistance to airflow in the airways [Desiraju 

and Agrawal 2016]. Impulse oscillometry might be useful as an indirect measure of airflow 

obstruction and helpful in individuals not able to perform forced breathing maneuvers that 

are required during the spirometry test. The impulse oscillometry test has been used for many 

years to measure changes in the airways of children with lung problems such as asthma and 

cystic fibrosis [Song et al. 2008; Komarow et al. 2011; Shi et al. 2012; Schulze et al. 2016]. 

More recently, impulse oscillometry has been used to investigate lung problems in adults 

exposed to dust or chemicals, such as World Trade Center emergency responders and soldiers 

returning from deployment overseas [Oppenheimer et al. 2007; Berger et al. 2013; Weinstein 

et al. 2016]. Over the years, researchers have developed reference (predictive) equations for 

different populations of children for oscillometry [Malmberg et al. 2002; Park et al. 2011; 

Lee et al. 2012; de Assumpção et al. 2016]. For adults, there are fewer reference equations 

available for oscillometry [Vogel and Smidt 1994; Newbury et al. 2008; Schulz et al. 2013]. 

The predicted values we used for oscillometry measures were based on gender and age 

according to reference values recommended by the manufacturer. Unlike predictive equations 

used for spirometry, the impulse oscillometry reference equations we used did not take into 

account height, race, or smoking status [Vogel and Smidt 1994].
Page 22 Health Hazard Evaluation Report 2017-0020-3316

We recommend starting a medical monitoring program because air sampling detected 

employee exposures to diacetyl and 2,3-pentanedione that exceeded the respective NIOSH 

RELs, and some participants reported respiratory symptoms. All employees involved in 

production tasks (e.g., roasting, interacting with open storage bins/containers of roasted 

coffee, grinding, weighing, flavoring, or packaging coffee) should participate in the 

workplace medical monitoring program. A medical monitoring program is a means of early 

identification of employees who might be developing lung disease (e.g., asthma, obliterative 

bronchiolitis) and can help prioritize interventions to prevent occupational lung disease. 

The NIOSH medical survey results can serve as a baseline for employees who participated, 

if they choose to share these results with their healthcare provider. In a workplace with risk 

of occupational lung disease, prevention of smoking-related lung disease is important and 

makes the detection of work-related adverse effects easier. The Centers for Disease Control 

and Prevention offers tools and resources for setting up a smoking cessation program [CDC 

2017b].

Conclusions

We identified full-shift employee exposures to diacetyl and 2,3-pentanedione in the 

production area that exceeded the NIOSH RELs. Overall, full-shift air concentrations of 

diacetyl and 2,3-pentanedione were consistently higher in the flavoring and grinding areas. 

The tasks of flavoring roasted coffee beans by hand, grinding flavored roasted coffee beans, 

and weighing and packaging roasted coffee were associated with higher diacetyl levels, 

likely due to the close proximity of the employee’s breathing zone to the roasted beans and 

flavoring. CO and CO2 levels were low throughout most of the facility; the highest CO and 

CO2 levels were observed in the production area of the facility, especially at the grinding 

area. Personal CO exposure increased during flavoring and grinding; however, personal 

CO levels were below the NIOSH ceiling limit. We observed opportunities to reduce strain 

on the body during certain tasks, decrease the risk of potential burns, and improve general 

small warehouse safety. Recommendations are made to reduce employee exposure to these 

occupational hazards and to protect respiratory health. 

Some employees reported mucous membrane symptoms and/or respiratory symptoms. One 

spirometry test result indicated mild obstruction. We recommend a medical monitoring 

program to identify any employees who might be developing lung disease (e.g., asthma, 

obliterative bronchiolitis) and to help management prioritize interventions to prevent 

occupational lung disease. All employees involved in production tasks (e.g., roasting, 

interacting with open storage bins/containers of roasted coffee, grinding, weighing, flavoring, 

or packaging coffee) should participate in the workplace medical monitoring program.

Recommendations

On the basis of our findings, we recommend the actions listed below. Our recommendations 

are based on an approach known as the hierarchy of controls. This approach groups actions 

by their likely effectiveness in reducing or removing hazards. In most cases, the preferred 
Health Hazard Evaluation Report 2017-0020-3316 Page 23

approach is to eliminate hazardous materials or processes and install engineering controls to 

reduce exposure or shield employees. 

Engineering Controls

Engineering controls reduce employees’ exposures by removing the hazard from the process 

or by placing a barrier between the hazard and the employee. Engineering controls protect 

employees effectively without placing primary responsibility of implementation on the 

employee. 

1. Work with a qualified ventilation engineer to install local exhaust ventilation at 

the grinders and around the coffee flavoring activities. Consider consolidating 

these activities into the same space, preferably near an exterior wall, to make the 

implementation of effective engineering controls easier.

2. Consult with a ventilation engineer to install a dilution ventilation system that meets 

current local mechanical codes. This system should consistently supply fresh, outdoor 

air to the production space. If properly selected, it could also be used to help heat 

and cool the production space throughout the year. The system should be operated 

whenever production activities are ongoing, but it could be shut off during unoccupied 

periods.

3. Conduct follow-up personal air sampling on employees with primary duties in the 

production area to verify that the modifications have been effective in reducing alphadiketone exposures to below the recommended exposure limits.

Administrative Controls

Administrative controls are employer-dictated work practices and policies implemented 

to reduce or prevent hazardous exposures. Their effectiveness depends on employer 

commitment and employee acceptance. Regular monitoring and reinforcement are necessary 

to ensure that policies and procedures are followed consistently.

1. Require lift gates for all deliveries of green beans. 

2. Use two employees when moving bags of green beans. Communicate throughout the 

lifting and moving of the bag so that both employees are lifting, lowering, and moving 

at the same time, avoiding jerking motions.

3. Pull the grinders forward to reduce the need to reach to the back of the table that they 

are sitting on.

4. Do not flavor roasted beans by hand. Instead, use an automatic mechanism that 

minimizes employee contact with flavored beans during blending. Until an alternative 

method of flavoring beans is introduced, to reduce strain on the body during shaking 

of flavoring buckets, keep hands below shoulder height, and do not shake the flavoring 

bucket over shoulder level.

5. To prevent excessive bending and reaching, store heavier, more commonly used items 

on shelves that are between knee and shoulder height.
Page 24 Health Hazard Evaluation Report 2017-0020-3316

6. Always pour green beans into the roaster hopper from the control panel side of the 

roaster to help prevent the possibility of contact with the hot roaster exhaust duct.

7. Turn heat sealers off after packaging tasks are completed.

8. Ensure the small rolling table near the roaster is not blocking the roaster’s emergency 

stop button.

9. Place a lock on the roaster control panel in accordance with OSHA control of 

hazardous energy (lockout/tagout) standard 29 CFR 1910.147. When an employee is 

cleaning the roaster, the employee performing the cleaning should keep the key on 

their person for the duration of the cleaning task.

10. Periodically clean the roaster’s exhaust in accordance with manufacturer instructions 

to remove chaff build up to reduce a fire hazard and to improve the efficiency, energy 

usage, and roaster performance. 

11.Include roaster exhaust checks and any future local exhaust systems in a preventive 

maintenance schedule to ensure they operate appropriately.

12.Continue to cover bins of roasted beans to reduce the overall emission of alphadiketones and other chemicals (e.g., CO, CO2

) into the workplace and lower employee 

exposure.

13.Eliminate the use of compressed air and dry sweeping as much as possible during 

cleaning. Instead, use a vacuum system with a high-efficiency particle air filter and wet 

methods whenever possible.

14. Ensure employees understand potential hazards (e.g., diacetyl, 2,3-pentanedione, CO, 

CO2, green and roasted coffee dust) in the workplace and how to protect themselves. 

OSHA’s Hazard Communication Standard, also known as the “Right to Know Law” 

[29 CFR 1910.1200] requires that employees are informed and trained on potential 

work hazards and associated safe practices, procedures, and protective measures. 

15.Ensure employees are educated to consider the risks of further exposure if they 

develop lower respiratory symptoms (e.g., cough, shortness of breath, wheezing) 

that are progressive and severe in degree. Employees should report new, persistent, 

or worsening symptoms to their personal healthcare providers and to a designated 

individual at this workplace. Employees with new, persistent, or worsening symptoms 

should share this report with their healthcare providers.

Personal Protective Equipment

The effectiveness of personal protective equipment in the form of respiratory protection in 

controlling respiratory exposures depends on avoiding breakdowns in implementation that 

result in insufficient protection. Proper use of respiratory protection (respirators) requires a 

comprehensive respiratory protection program and a high level of employee and management 

involvement and commitment to assure that the right type of respirator is chosen for each 

hazard, respirators fit users and are maintained in good working order, and respirators are 

worn when they are needed. Supporting programs such as training, change-out schedules, 

and medical assessment might be necessary. Respirators should not be the sole method for 
Health Hazard Evaluation Report 2017-0020-3316 Page 25

controlling hazardous inhalation exposures. Rather, respirators should be used until effective 

engineering and administrative controls are in place. 

1. In addition to engineering and administrative controls, respiratory protection is a 

potential option to further reduce exposures to alpha-diketones (e.g., diacetyl and 

2,3-pentanedione). If follow-up air sampling after engineering controls have been 

installed and administrative controls are implemented indicates levels of diacetyl 

and 2,3-pentanedione remain above their respective NIOSH REL or STEL, or if a 

long delay is anticipated before these controls can be put into place, we recommend 

respiratory protection be used during tasks with elevated exposures. Respirators used 

to reduce exposures to diacetyl and 2,3-pentanedione should be NIOSH-certified and 

equipped with organic vapor cartridges. The choice of respirator should be guided 

by personal exposure sampling for diacetyl and 2,3-pentanedione (NIOSH 2004). 

For reference, air-purifying half-face respirators have an assigned protection factor 

(APF) of 10, and air-purifying full-face respirators have an APF of 50. Also, there are 

powered-air purifying respirators that have APFs of 25, 50, or 1000. A respirator’s 

APF refers to the maximal level of protectiveness a specific respirator design can 

achieve under laboratory conditions. The OSHA APFs can be found in Table 1 of 

OSHA Respiratory Protection Standard at https://www.osha.gov/pls/oshaweb/owadisp.

show_document?p_table=STANDARDS&p_id=12716. 

If respiratory protection is used, a written respiratory protection program should be 

implemented as required by the OSHA Respiratory Protection Standard (29 CFR 

1910.134), including training, fit testing, maintenance, and use requirements. 

2. Continue to offer employees the voluntary use of N95 disposable filtering-facepiece 

respirators when moving burlap bags of green beans, when cleaning the exhaust 

system of chaff, when emptying the chaff containers, or when cleaning the green 

bean storage area. N95 respirators should be available in various sizes, and each 

potential N95 user should receive a copy of Appendix D of the OSHA Respiratory 

Protection Standard (https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_

table=standards&p_id=9784). Information about Appendix D and voluntary use 

of respirators can be found on the OSHA website at https://www.osha.gov/video/

respiratory_protection/voluntaryuse_transcript.html.

 Please be aware that N95s are not protective against alpha-diketones (diacetyl, 

2,3-pentanedione, or 2,3-hexanedione). In cases of dual exposure to dust and alphadiketones, such as those in flavorings, NIOSH-certified organic vapor cartridges 

(for the alpha-diketones) and particulate cartridges/filters (for the dust) would be 

warranted.

Medical Monitoring

The purpose of a medical monitoring program is to help assure the health of employees 

who have workplace exposures (e.g., diacetyl, 2,3-pentanedione, green coffee beans/dust) 

known to pose risk for potentially serious health conditions such as asthma or obliterative 

bronchiolitis. 
Page 26 Health Hazard Evaluation Report 2017-0020-3316

1. Some coffee processing workers who flavor coffee or have exposure to flavored 

coffee production using the flavoring chemicals diacetyl and 2,3-pentanedione 

have developed obliterative bronchiolitis [Bailey et al. 2015]. Headspace analyses 

of the liquid flavorings used to flavor coffee in this facility identified diacetyl and 

2,3-pentandione, and personal air sampling conducted in the production area identified 

levels in air exceeding the NIOSH REL. In view of this, as detailed in the NIOSH 

Criteria Document [NIOSH 2016], we recommend that the employer implement a 

medical monitoring program for all employees who work in or enter production areas 

for a total of 40 or more hours per year. According to the NIOSH Criteria Document, 

employees should have baseline evaluations before they are allowed to work in or 

enter areas where they might be exposed to diacetyl, 2,3-pentanedione, or similar 

flavoring compounds. The spirometry we conducted in January 2017 could serve as a 

baseline for survey participants. 

2. Employees in the medical monitoring program should be evaluated with a 

questionnaire (to obtain health and work task information) and spirometry (to assess 

lung function) every six months due to the potentially rapid development of lung 

disease. If an employee is identified to have lung disease from exposure to diacetyl, 

2,3-pentanedione, or a similar flavoring compound, then all employees who perform 

similar job tasks or have a similar or greater potential for exposure should be evaluated 

every three months [NIOSH 2016].

Smoking Cessation Program

In a workplace with risk of occupational lung disease, prevention of smoking-related lung 

disease is important and makes the detection of work-related adverse effects easier. We 

recommend implementing a smoking cessation program to assist employees to stop smoking. 

The Centers for Disease Control and Prevention offers tools and resources for setting up a 

smoking cessation program [CDC 2017b].
Health Hazard Evaluation Report 2017-0020-3316 Page 27

Table A1. OSHA Methods 1013/1016 personal and area full-shift air sampling results by location, 

NIOSH survey, January 2017

Above Minimum Maximum Sample Above Analyte Location N LOD Concentration Concentration Type REL N N (%) (ppb) (ppb)

Diacetyl Personal Off-site Work Area 1 0 (0%) <0.2 <0.2 0

Diacetyl Personal Production Area 4 4 (100%) 7.4 20.7 4

Diacetyl Area Administration 2 2 (100%) 1.8 2.0 N/A

Diacetyl Area Flavoring 2 2 (100%) 10.0 12.1 N/A

Diacetyl Area Green Bean Storage 2 2 (100%) 9.8 11.6 N/A

Diacetyl Area Grinding 6 6 (100%) 12.6 27.7 N/A

Diacetyl Area Outside 2 1 (50%) <0.3 0.5 N/A

Diacetyl Area Production Area 2 2 (100%) 8.3 9.5 N/A

Diacetyl Area Production Office 2 2 (100%) 10.2 11.7 N/A

Diacetyl Area Roasting 2 2 (100%) 5.4 12.6 N/A

2,3-Pentanedione Personal Off-site Work Area 1 1 (100%) 0.2 0.2 0

2,3-Pentanedione Personal Production Area 4 4 (100%) 7.1 24.0 1

2,3-Pentanedione Area Administration 2 2 (100%) 1.7 2.1 N/A

2,3-Pentanedione Area Flavoring 2 2 (100%) 9.7 11.0 N/A

2,3-Pentanedione Area Green Bean Storage 2 2 (100%) 9.2 10.2 N/A

2,3-Pentanedione Area Grinding 6 6 (100%) 12.1 28.0 N/A

2,3-Pentanedione Area Outside 2 0 (0%) <0.3 <0.3 N/A

2,3-Pentanedione Area Production Area 2 2 (100%) 7.1 9.2 N/A

2,3-Pentanedione Area Production Office 2 2 (100%) 9.7 11.1 N/A

2,3-Pentanedione Area Roasting 2 2 (100%) 4.9 11.1 N/A

2,3-Hexanedione Personal Off-site Work Area 1 0 (0%) <0.1 <0.1 —

2,3-Hexanedione Personal Production Area 4 1 (25%) <0.2 0.5 —

2,3-Hexanedione Area Administration 2 0 (0%) <0.2 <0.2 N/A

2,3-Hexanedione Area Flavoring 2 0 (0%) <0.2 <0.2 N/A

2,3-Hexanedione Area Green Bean Storage 2 0 (0%) <0.2 <0.2 N/A

2,3-Hexanedione Area Grinding 6 4 (67%) <0.2 0.7 N/A

2,3-Hexanedione Area Outside 2 0 (0%) <0.2 <0.2 N/A

2,3-Hexanedione Area Production Area 2 0 (0%) <0.2 <0.2 N/A

2,3-Hexanedione Area Production Office 2 0 (0%) <0.2 <0.2 N/A

2,3-Hexanedione Area Roasting 2 0 (0%) <0.2 <0.2 N/A

Note: OSHA=Occupational Safety and Health Administration; NIOSH=National Institute for Occupational Safety 

and Health; N=number of samples; Above LOD N (%)=number and percentage of samples above the limit of 

detection (LOD); ppb=parts per billion; < indicates below the LOD; Above REL N=number of samples above the 

NIOSH recommended exposure limit (REL); N/A indicates that NIOSH RELs are specified for personal air samples 

and cannot be directly applied to area air samples; “—” indicates there is currently no REL for 2,3-hexanedione.

Appendix A: Tables
Page 28 Health Hazard Evaluation Report 2017-0020-3316

Table A2. OSHA Methods 1013/1016 personal task-based air sampling results, NIOSH survey, January 2017

Mean 

Above Minimum Maximum (minutes) Sample Analyte Task N LOD Concentration Concentration Sample Type N (%) (ppb) (ppb) Duration 

(range) 

Diacetyl Personal Cleaning Roaster 1 1 (100%) 2.9 2.9 —

Diacetyl Personal Flavor coffee 2 2 (100%) 22.7 67.2 10 (6–13)

Diacetyl Personal Grind coffee beans 2 2 (100%) 11.9 32.0 9 (7–11)

Diacetyl Personal Move roasted coffee 1 1 (100%) 13.3 13.3 —

Diacetyl Personal Package coffee 4 4 (100%) 23.0 53.2 13 (10–17)

Diacetyl Personal Roast coffee beans 4 4 (100%) 5.8 15.9 12 (7–14)

Diacetyl Personal Work with green beans 1 1 (100%) 4.8 4.8 —

2,3-Pentanedione Personal Cleaning Roaster 1 1 (100%) 3.8 3.8 —

2,3-Pentanedione Personal Flavor coffee 2 2 (100%) 24.2 82.6 10 (6–13)

2,3-Pentanedione Personal Grind coffee beans 2 2 (100%) 18.3 36.4 9 (7–11)

2,3-Pentanedione Personal Move roasted coffee 1 1 (100%) 13.7 13.7 —

2,3-Pentanedione Personal Package coffee 4 4 (100%) 29.0 56.8 13 (10–17)

2,3-Pentanedione Personal Roast coffee beans 4 4 (100%) 4.6 19.0 12 (7–14)

2,3-Pentanedione Personal Work with green beans 1 1 (100%) 6.0 6.0 —

2,3-Hexanedione Personal Cleaning Roaster 1 0 (0%) <0.7 <0.7 —

2,3-Hexanedione Personal Flavor coffee 2 0 (0%) <0.8 <1.7 10 (6–13)

2,3-Hexanedione Personal Grind coffee beans 2 1 (50%) <=1.3 1.3 9 (7–11)

2,3-Hexanedione Personal Move roasted coffee 1 0 (0%) <0.7 <0.7 —

2,3-Hexanedione Personal Package coffee 4 2 (50%) <0.6 2.0 13 (10–17)

2,3-Hexanedione Personal Roast coffee beans 4 0 (0%) <0.7 <1.5 12 (7–14)

2,3-Hexanedione Personal Work with green beans 1 0 (0%) <1.0 <1.0 —

Note: OSHA=Occupational Safety and Health Administration; NIOSH=National Institute for Occupational Safety and 

Health; N=number of samples; Above LOD N (%)=number and percentage of samples above the limit of detection (LOD); 

ppb=parts per billion; < indicates below the LOD; <= indicates less than or equal to the LOD; “—” indicates that only one 

sample was taken so a mean could not be calculated and a range is not reported.
Health Hazard Evaluation Report 2017-0020-3316 Page 29

Diacetyl 2,3-Pentanedione 2,3-Hexanedione Source Description (ppb) (ppb) (ppb)

Table A3. Instantaneous evacuated canister method* source air sampling results, NIOSH survey, January 2017

Flavoring roasted whole beans with butterscotch flavoring, sampled at 

top of mixing bucket 27.5 68.6 <9.6

Grinding butterscotch-flavored coffee, sampled at grinder discharge (1) 65.5 61.9 1.9

Grinding butterscotch-flavored coffee, sampled at grinder discharge (2) 489 604 13.7

Headspace of butterscotch flavoring bottle <3.8 1,469 <9.4

Note: NIOSH=National Institute for Occupational Safety and Health; ppb=parts per billion; < indicates below the limit of 

detection.

*Sampling duration approximately 30 seconds; source air samples were collected by placing the inlet of the canister sampler 

at the source.

Table A4. Instantaneous evacuated canister pre- and post-shift background air sampling results, 

NIOSH survey, January 2017

Concentration Analyte Sample Type Sample Location Pre- or Post-shift (ppb)

Diacetyl Background Administration Pre-shift 2.7

Diacetyl Background Administration Post-shift 5.1

Diacetyl Background Production Office Pre-shift 10.3

Diacetyl Background Production Office Post-shift 23.1

Diacetyl Background Production Area Pre-shift 7.1

Diacetyl Background Production Area Post-shift 21.3

2,3-Pentanedione Background Administration Pre-shift 1.6

2,3-Pentanedione Background Administration Post-shift 5.5

2,3-Pentanedione Background Production Office Pre-shift 7.9

2,3-Pentanedione Background Production Office Post-shift 27.2

2,3-Pentanedione Background Production Area Pre-shift 5.7

2,3-Pentanedione Background Production Area Post-shift 24.7

2,3-Hexanedione Background Administration Pre-shift 1.0

2,3-Hexanedione Background Administration Post-shift 1.0

2,3-Hexanedione Background Production Office Pre-shift 1.0

2,3-Hexanedione Background Production Office Post-shift 0.9

2,3-Hexanedione Background Production Area Pre-shift 0.9

2,3-Hexanedione Background Production Area Post-shift 5.9

Note: NIOSH=National Institute for Occupational Safety and Health; ppb=parts per billion.
Page 30 Health Hazard Evaluation Report 2017-0020-3316

Table A5. Headspace analysis results* for bulk samples of roasted coffee beans and 

flavoring, NIOSH survey, January 2017

Diacetyl 2,3-Pentanedione 2,3-Hexanedione Bulk Sample Description (ppb) (ppb) (ppb)

Whole roasted coffee beans #1 2,965 3,620 <0.6

Whole roasted coffee beans #2 3,886 4,599 <0.6

Whole roasted coffee beans #3 4,391 4,431 <0.6

Whole roasted coffee beans #4 6,966 8,014 <0.6

Whole roasted coffee beans #5 1,704 3,709 <0.6

Whole roasted coffee beans #6 3,582 3,750 <0.6

Whole roasted coffee beans #7 1,384 1,526 <0.6

Whole roasted coffee beans #8 4,455 5,565 <0.6

Whole roasted coffee beans #9 7,013 7,982 <0.6

Whole roasted coffee beans #10 3,842 5,025 <0.6

Butterscotch flavoring <0.3 6,866 <0.6

Note: NIOSH=National Institute for Occupational Safety and Health; ppb=parts per billion; < 

indicates below the limit of detection.

*The roasted coffee beans off-gassed for different amounts of time, and this could be responsible for 

some of the differences in headspace analysis results.
Health Hazard Evaluation Report 2017-0020-3316 Page 31

Table A6. Real-time* area air monitoring for carbon dioxide, carbon monoxide, temperature, 

and relative humidity, NIOSH survey, January 2017

Area Sample Location Measurement Minimum Maximum Average

Administrative CO2 (ppm) 644.0 1,595.0 928.3

CO (ppm) <0.1 1.1 0.2

Temperature (°F) 71.3 78.4 74.9

Relative Humidity (%) 21.8 41.4 29.9

Flavoring CO2 (ppm) 430.0 1,774.0 1,150.0

CO (ppm) <0.1 8.1 2.1

Temperature (°F) 62.6 88.8 80.0

Relative Humidity (%) 25.0 48.4 32.7

Green Bean Storage CO2 (ppm) 500.0 1,785.0 1,134.0

CO (ppm) 0.6 6.5 3.5

Temperature (°F) 69.4 82.7 77.9

Relative Humidity (%) 24.4 31.6 28.6

Grinding CO2 (ppm) 428.0 2,015.0 1,197.9

CO (ppm) <0.1 78.9 3.8

Temperature (°F) 67.4 86.1 79.6

Relative Humidity (%) 21.3 46.8 30.5

Production Area CO2 (ppm) 386.0 1,707.0 1,216.5

CO (ppm) <0.1 9.3 3.6

Temperature (°F) 64.3 82.7 74.6

Relative Humidity (%) — — —

Roasting CO2 (ppm) 400.0 2,041.0 1,099.3

CO (ppm) <0.1 2.4 0.3

Temperature (°F) 67.4 91.3 84.3

Relative Humidity (%) 16.1 33.7 20.8

Note: NIOSH=National Institute for Occupational Safety and Health; ppm=parts per million; CO2

=carbon 

dioxide; CO=carbon monoxide; °F=degrees Fahrenheit, “—”=no data.

*Real-time instruments were set to log data at 10-second intervals.
Page 32 Health Hazard Evaluation Report 2017-0020-3316

Table A7. Real-time total volatile organic compound sampling by 

area, NIOSH survey, January 2017

Minimum Maximum Average Area Sample Location (ppb) (ppb) (ppb)

Flavoring 16 11,907 4,405

Roasting <0.1 1,911 657

Administrative <0.1 2,036 456

Production Office <0.1 4,770 648

Note: NIOSH=National Institute for Occupational Safety and Health;

 ppb=parts per billion; < indicates below the limit of detection.

Table A8. Real-time* personal air monitoring results for carbon 

monoxide, NIOSH survey, January 2017

Minimum Maximum Average Sample ID (ppm) (ppm) (ppm)

1 <0.1 19 2.7

2 <0.1 47 1.6

3 <0.1 157 2.6

4 <0.1 55 1.9

Note: NIOSH=National Institute for Occupational Safety and Health; 

ppm=parts per million; < indicates below the limit of detection.

*Personal CO monitors were set to log data at 10-second intervals.
Health Hazard Evaluation Report 2017-0020-3316 Page 33

Figure B1. Real-time* personal carbon monoxide air monitoring levels for one employee, 

NIOSH survey, January 2017. Note: CO=carbon monoxide; ppm=parts per million.

*Personal CO monitor was set to log data at 10-second intervals.

Appendix B: Figures

0

5

10

15

20

25

9:329:429:52

10:0210:1210:2210:3210:4210:5211:0211:1211:2211:3211:4211:5212:0212:1212:22

CO (ppm)

Time of Day 

Flavoring coffee

Grinding flavored coffee
Page 34 Health Hazard Evaluation Report 2017-0020-3316

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Health Hazard Evaluation Report 2017-0020-3316 Page 43

Keywords: NAICS 311920 (Coffee roasting), Ohio, diacetyl, 2,3-pentanedione, 2,3-hexanedione, coffee, flavorings, carbon monoxide, carbon dioxide, volatile organic compounds 

(VOCs). 
Page 44 Health Hazard Evaluation Report 2017-0020-3316

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Acknowledgments

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Data Analysis Support: Nicole Edwards, Kathleen Fedan, and Brian Tift

Laboratory Support: Dru Burns, Kyle Hatcher, Ryan LeBouf, and Anand Ranpara

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Recommended citation for this report:

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Department of Health and Human Services, Centers for Disease Control and 

Prevention, National Institute for Occupational Safety and Health, NIOSH HHE 

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