Health Hazard Evaluation Report 2016-0120-3307 Page 1

Evaluation of Chemical Exposures at Two Vape 

Shops in Texas

HHE Report 2016-0120-3307

May 2018

Leonard M. Zwack, ScD

Sophia Chiu, MD, MPH

Ryan F. LeBouf, PhD, CIH
Page 2 Health Hazard Evaluation Report 2016-0120-3307

Contents

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

Abbreviations ..................................... iii

Introduction......................................... 1

Methods ............................................... 2

Results .................................................. 4

Discussion .......................................... 12

Conclusions........................................ 15

Recommendations............................. 15

Appendix A ........................................ 17

Appendix B ........................................ 19

References.......................................... 22

Acknowledgements........................... 27

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. Photo by NIOSH.
Health Hazard Evaluation Report 2016-0120-3307 Page i

We evaluated exposures to 

vaping-related chemicals in 

two vape shops. Exposures 

to flavoring chemicals 

(diacetyl, 2,3-pentanedione) 

were all below occupational 

exposure limits. Exposure to 

formaldehyde, other volatile 

organic compounds, and 

nicotine were also low. We 

found evidence of residual 

nicotine on commonly 

touched surfaces throughout 

both vape shops.

Highlights of this Evaluation

The Texas Department of State Health Services asked the Health Hazard Evaluation Program 

to evaluate employees’ potential exposure to vaping chemicals in two shops.

What We Did

● We visited the vape shops in July 2016.

● We collected air samples for flavoring chemicals (diacetyl, 2,3-pentanedione, 

2,3-hexanedione, and acetoin), nicotine, volatile organic compounds, and formaldehyde. 

● We took wipe samples for nicotine and metals on commonly touched surfaces.

● We interviewed employees about their work 

and health. 

What We Found

● Employees vaped at work.

● Concentrations of flavoring chemicals in our air 

samples were below occupational exposure limits.

● Nicotine was detected on commonly touched 

surfaces throughout both shops.

● All employees wore chemical protective gloves 

when they were mixing e-liquids and working 

with concentrated nicotine solutions.

● Some employees reported liquid nicotine coming 

into contact with their skin or eyes while handling 

liquid nicotine or vaporizers. 

● None of the employees reported symptoms 

consistent with either nicotine toxicity or 

exposures to flavorings in the past 4 weeks.

What the Employer Can Do

● Implement a policy prohibiting vaping in the shop with e-liquids that contain diacetyl 

and 2,3-pentanedione. These chemicals are often found in dairy flavorings, brown 

flavorings such as butterscotch and caramel, and some fruit flavorings.

● Place a spill tray or drip pan under the large carboys to prevent liquid nicotine from 

spilling onto the counter during transfer from the large carboys to the transfer bottles.

● Inspect and replace broken caps and droppers on the bottles containing the liquid 

flavorings and nicotine.
Page ii Health Hazard Evaluation Report 2016-0120-3307

What Employees Can Do

● Wear nitrile gloves whenever handling liquids that contain nicotine.

● Wear nitrile gloves whenever handling customers’ vaporizers.

● Wear nitrile gloves, a long-sleeve laboratory coat, and goggles when working with 

concentrated nicotine solutions.

● Clean workstations and other commonly touched surfaces throughout the day.
Health Hazard Evaluation Report 2016-0120-3307 Page iii

Abbreviations

μg/m3 Micrograms per cubic meter

μg/sample Micrograms per sample

ACGIH® American Conference of Governmental Industrial Hygienists

CFR Code of Federal Regulations

FEMA Flavor and Extract Manufacturers Association of the United States

mg/mL Milligrams per milliliter

mL Milliliter

ND Not detected

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

PPE Personal protective equipment

REL Recommended exposure limit

STEL Short-term exposure limit

TLV® Threshold limit value

TWA Time-weighted average

VOC Volatile organic compound
Page iv Health Hazard Evaluation Report 2016-0120-3307

This page left intentionally blank
Health Hazard Evaluation Report 2016-0120-3307 Page 1

Introduction

The Texas Department of State Health Services requested assistance from the Health 

Hazard Evaluation Program. They asked us to evaluate employees’ exposures to chemicals 

associated with vaping at two vape shops. We visited the two shops in July 2016. We met 

with employer and employee representatives, measured employees’ exposures to vapingrelated chemicals, and interviewed employees about their work and health.

Background

Vaping is the process in which liquid is heated by an atomizer housed in an electronic 

nicotine delivery system or “e-cigarette.” The liquid becomes an aerosol of liquid droplets 

in air (commonly referred to as vapor) that the user inhales. The liquid (known as e-liquid 

or e-juice) is typically comprised of propylene glycol, vegetable glycerin, nicotine, and 

flavoring chemicals. Formaldehyde can also be generated as a breakdown product of 

propylene glycol. Other chemicals that have been associated with vaping include flavorings, 

nicotine, glycols, glycerin, other volatile organic compounds (VOCs), metals, and ultrafine 

particles composed of these chemicals, among others [AIHA 2014]. Diacetyl and its 

substitute, 2,3-pentanedione, are widely used flavoring chemicals. Serious respiratory disease 

and decreased lung function have been reported in employees exposed to diacetyl [NIOSH 

2016]. Other flavoring chemicals that can be used in e-liquid such as acetaldehyde and 

acetoin can also have adverse respiratory health effects [NIOSH 2016]. A laboratory study 

has shown that diacetyl and 2,3-pentanedione are present in the heated vapor that e-cigarettes 

produce [Allen et al. 2016]. A previous health hazard evaluation of exposures at a vape shop 

found detectable levels of flavorings in the air of the shop [NIOSH 2017]. Other studies have 

directly measured exposures to vaping-related chemicals in well-characterized rooms and 

chambers, though they often did not sample for flavoring chemicals [Czogala et al. 2014; 

Maloney et al. 2016; Schober et al. 2014; Schripp et al. 2013]. 

At the time of our visit, the same company operated two vape shops (shop A and shop B) and 

had 17 total employees. Both shops sold e-cigarettes and the e-liquids used in e-cigarettes. 

The shops were open from 10 a.m. to 8 p.m. Monday through Saturday. On Sunday, they 

were open from 12 p.m. to 5 p.m. The employer estimated that shop A was approximately 

2,000 square feet and included retail space, a lounge, an attached warehouse, and some 

offices. We observed shop B to be substantially smaller than shop A, containing retail space, 

a lounge, and some office space. The lounge area was a place for customers to congregate 

and vape. Shift lengths were variable, with most employees working up to 10 hours, 

depending upon the day. Generally, we observed approximately five employees working in 

shop A at any one time. Shop B typically had two or three employees working. 

These vape shops purchased premixed e-liquids from a supplier and resold them to 

customers. They also hand mixed custom e-liquid blends according to customers’ tastes and 

nicotine, propylene glycol, and vegetable glycerin preferences. Hand mixing of chemicals 

potentially exposed employees to concentrated levels of liquid nicotine. All counter 

employees generally performed the same tasks each day. The primary task was hand mixing 

of e-liquids for customers at a counter. Employees used liquid droppers to transfer the 
Page 2 Health Hazard Evaluation Report 2016-0120-3307

flavoring chemicals into various sized bottles of e-liquid that the customers purchased. In 

both shops, employees also refilled small bottles of nicotine, propylene glycol, and vegetable 

glycerin solutions from large carboys located in a separate room (Figure 1). 

Figure 1. Carboys containing nicotine, propylene glycol, and vegetable glycerin in the back room of a 

shop. One of the carboys appeared to be leaking, as indicated by fluid on the counter surface below 

the carboy nozzle and shown inside the yellow circle drawn on the figure. Photo by NIOSH.

Methods

Our primary objective was to evaluate employees’ potential exposures to chemicals 

associated with vaping in the shop. Our work involved (1) sampling air for specific flavoring 

chemicals associated with respiratory disease; (2) sampling air for nicotine, formaldehyde, 

and other VOCs; (3) sampling work surfaces for metals and nicotine; (4) observing work 

practices; and (5) conducting confidential medical interviews with employees.

Air Sampling for Vaping-related Chemicals

We collected personal air samples for specific flavoring chemicals and formaldehyde on 

employees during their full work shifts. For shop A, we sampled five employees on days 

1 and 2. For shop B, we sampled two employees on day 1 and three employees on day 2. 

We selected two locations in each shop to sample general room air (referred to as “area” 

air samples). Area samples were collected for nicotine, flavoring chemicals, VOCs, and 

formaldehyde. For shop A, one set of area air samples was collected directly at the end of the 

mixing counter. The other was taken in the back of the shop, near an employee who mixed 

e-liquids to fill internet orders. For shop B, one set of area air samples was collected at the

end of the mixing counter, while the other set was collected behind the mixing counter.
Health Hazard Evaluation Report 2016-0120-3307 Page 3

Flavoring Chemicals

We measured flavoring chemicals using two air sampling methods, silica gel tubes and 

evacuated canisters. The silica gel tube method was developed by the Occupational Safety 

and Health Administration (OSHA) for measuring flavoring chemicals in the air. The 

evacuated canister method is experimental and still undergoing validation by the National 

Institute for Occupational Safety and Health (NIOSH). 

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

and 2,3-hexanedione using sets of two silica gel sorbent tubes in series with pumps calibrated to 

a flow rate of 50 cubic centimeters per minute. We collected samples at both shops and at both 

area sampling locations over 2 days. These samples were analyzed for flavoring chemicals in 

accordance with OSHA Method 1013 [OSHA 2008] and OSHA Method 1016 [OSHA 2010a]; 

however, an alternate detector (mass spectrometer) was used to increase method sensitivity 

[LeBouf and Simmons 2017]. The analytical limits of detection were as follows: acetoin, 

0.04 micrograms per sample (μg/sample); diacetyl, 0.03 μg/sample; 2,3-pentanedione, 

0.03 μg/sample; and 2,3-hexanedione, 0.04 μg/sample. The limits of quantitation were as 

follows: acetoin, 0.14 μg/sample; diacetyl, 0.088 μg/sample; 2,3-pentanedione, 

0.094 μg/sample; and 2,3-hexanedione, 0.13 μg/sample.

We used evacuated canisters to collect personal and area air samples for diacetyl, 

2,3-pentanedione, 2,3-hexanedione, and acetaldehyde. The evacuated canister sampling 

setup consisted of a 450-milliliter (mL) evacuated canister equipped with a restricted 

flow controller set to collect a 9-hour air sample. The canister air samples were analyzed 

using a preconcentrator/gas chromatograph/mass spectrometer system according to a 

published method validation study [LeBouf et al. 2012] with the following modifications: 

the preconcentrator was an Entech Instruments Model 7200, and four additional chemicals, 

acetaldehyde, diacetyl, 2,3-pentanedione, and 2,3-hexanedione, were included in the analysis. 

The limit of detection of the sampling and analytical method is the lowest mass that can be 

currently measured. The limit of quantitation is the lowest mass that can be reported with 

acceptable precision. The analytical limits of detection were as follows: acetaldehyde, 

0.3 parts per billion (ppb); diacetyl, 0.3 ppb; 2,3-pentanedione, 0.4 ppb; 2,3-hexanedione, 

0.6 ppb. The limits of quantitation were as follows: acetaldehyde, 0.89 ppb; diacetyl, 

0.86 ppb; 2,3-pentanedione, 1.2 ppb; 2,3-hexanedione, 2.1 ppb. These detection and 

quantitation limits were multiplied by the individual sample pressure dilution factors to 

obtain the minimum detectable and quantifiable concentrations displayed in the results table 

footnotes. At present, this canister method is partially validated [LeBouf et al. 2012] and not 

considered the standard method.

Formaldehyde in Air

We collected full-shift personal and area air samples for formaldehyde using SKC UMEx 

100 passive badges. The air samples were collected and analyzed in accordance with OSHA 

Method 1007 [OSHA 2005]. 
Page 4 Health Hazard Evaluation Report 2016-0120-3307

Nicotine in Air

We collected area air samples for nicotine using XAD-4 tubes with pumps calibrated to a 

flow rate of 200 cubic centimeters per minute. The air samples were analyzed in accordance 

with NIOSH Method 2551 [NIOSH 2018]. 

Volatile Organic Compounds in Air

The personal and area canister sampling described above was also able to quantify 16 

target VOCs. Additional compounds were tentatively identified using the National Institute 

of Standards and Technology 2011 mass spectral library (NIST/EPA/NIH Mass Spectral 

Database NIST11, Scientific Instrument Services, Ringoes, NJ).

Surface Sampling for Elements and Nicotine

We collected wipe samples for elements (minerals and metals) from several surfaces in the vape

shop that employees commonly touched during their work. These samples were collected using

premoistened Palintest® Dust Wipes following NIOSH Method 9102 [NIOSH 2018]. We used

a disposable template to collect each wipe sample over an area of 100 square centimeters. The

wipe samples were analyzed according to NIOSH Method 7303 [NIOSH 2018].

We collected surface wipe samples for nicotine using sterile cotton swabs (ITW Texwipe 

Model STX705W) that were wetted with ethyl acetate and 0.01% triethylamine. Most 

samples were collected using a disposable template, covering an area of 100 square 

centimeters. The wipe samples were analyzed according to NIOSH Method 2551, which was 

modified to incorporate the use of cotton swabs [NIOSH 2018].

Confidential Employee Interviews

We invited all employees working in both shops during our visit to participate in confidential 

interviews. During the interviews, we discussed workplace exposures, work history and 

practices, medical history, and employees’ experiences with vaping. 

Results

Workplace Observations

Employees and customers vaped inside the shop. During the site visit, employees reported 

that the air inside the shop could get “cloudy” or hazy when many people were vaping 

simultaneously. However, we did not observe haziness or lingering vapor clouds in shop A. 

In shop B, we noticed some minimal haziness during the second day of sampling. On the 

days of our visits, we observed that employees did most of the vaping inside the shop. 

Customers would sometimes vape while sampling flavors or waiting to be helped by a staff 

member, but this practice was relatively infrequent compared to the employees’ vaping. 

When customers did sample flavors, they stood directly across from employees working at 

the counter. 
Health Hazard Evaluation Report 2016-0120-3307 Page 5

Ventilation in shop A was provided by two air handling units attached to the ceiling that 

delivered ducted supply air to the entire shop. Employees in the shop reported that they 

periodically changed the air handling unit filters. We were not able to look at the air handling 

units in shop B because they were located above the suspended ceiling tiles. However, we 

observed that supply air vents in the ceiling provided conditioned air. Employees stated that 

they did not have control over the air handling units in this shop, and that the building owner 

maintained it.

Employees reported that they cleaned floors, counters, displays, and the counter with cleaning 

agents including Clorox® wipes and sprays, Pine-Sol® surface cleaner, and glass cleaners. 

While we were at the shops, we observed employees cleaning the mixing counter multiple times 

throughout the day.

At a mixing station in the back of shop B, we observed a transfer bottle of nicotine solution 

that appeared to be leaking. We also observed older bottles of flavoring chemicals that 

appeared to be damaged. We did not observe this mixing station to be in use during our 

2 days in this shop. This mixing station was located in the same room where employees 

ate lunch. At both shops, we observed that the flavoring chemicals and nicotine used at 

the mixing counters were stored in secondary containers. This included both glass vials 

(flavorings, nicotine) as well as plastic carboys (nicotine). None of these containers was 

labeled as required by the OSHA hazard communication standard [1910.1200]. This standard 

requires that all hazardous chemicals stored outside of their original container have a label 

that contains, at a minimum, the identity of the hazardous chemical and the hazards present.

At the nicotine mixing station in the back of shop A, we observed that one of the large 

carboys had a small leak (Figure 1). The shop did not have any secondary containment in 

place, such as a spill tray or drip pan to catch liquids leaking from carboys and accumulating 

on the counter below the carboy.

Personal Protective Equipment

The company provided employees with nitrile gloves for use when mixing e-liquids and 

when working with chemicals. We observed that employees always wore gloves during 

these tasks, as required by company policy. When wearing gloves, employees generally used 

a new pair for each bottle of e-liquid they were mixing and did not reuse gloves between 

e-liquid mixing tasks. Sometimes, employees would change their gloves multiple times when 

working with one customer. Employees transferring nicotine from the large carboys to the 

smaller transfer bottles wore gloves during this process.

Air Sampling Results

Flavoring Chemicals

Table 1 presents the personal air monitoring results for flavoring chemicals using silica 

gel tubes and analyzed using the modified OSHA methodology. The results of the 

experimental evacuated canister sampling are presented in Appendix A. The conclusions and 
Page 6 Health Hazard Evaluation Report 2016-0120-3307

None of the personal air samples for the flavoring chemicals were above any 8-hour timeweighted average (TWA) occupational exposure limit (OEL). The lowest OEL for these 

chemicals was the NIOSH recommended exposure limit (REL) of 5 ppb for diacetyl and 

9.3 ppb for 2,3-pentanedione. OELs for 2,3-hexanedione and acetoin have not been 

established. Appendix B describes these and other OELs in more detail.

Table 1. Personal air sampling results for flavoring chemicals (ppb)*

Employee Date Sample duration 

(minutes)†

Diacetyl 2,3-

pentanedione

2,3-

hexanedione

Acetoin

Shop A

1 Day 1 449 [0.4] [1.3] ND ND

1 Day 2 461 ND 1.4 ND ND

2 Day 1 377 ND 0.8 ND ND

3 Day 1 358 [0.3] 1.5 ND ND

4 Day 1 367 ND [1.3] ND ND

4 Day 2 363 ND 1.3 ND ND

5 Day 1 373 ND 1.4 ND ND

5 Day 2 527 [0.3] 1.4 ND ND

6 Day 2 529 ND 1.7 ND [1.8]

7 Day 2 558 [0.3] 1.5 ND ND

Shop B

8 Day 1 432 ND ND ND ND

8 Day 2 508 ND ND ND ND

9 Day 1 507 ND ND ND ND

10 Day 2 521 ND ND ND ND

11 Day 2 520 ND [0.4] ND ND

ACGIH TLV 10 — — —

NIOSH REL 5.0 9.3 — —

OSHA PEL — — — —

ACGIH TLV = American Conference of Governmental Industrial Hygienists threshold limit value

OSHA PEL = OSHA permissible exposure limit

ND = Not detected

[ ] = Estimated concentration; this concentration was between the minimum detectable and 

minimum quantifiable concentrations.

*The minimum detectable concentration range was 0.3–0.4 ppb for diacetyl and 2,3-pentanedione, 

0.4–0.6 ppb for 2,3-hexanedione, and 1.4–1.9 ppb for acetoin. The minimum quantifiable 

concentration range was 1.0–1.3 ppb for diacetyl and 2,3-pentanedione, and 4.7–6.4 ppb 

for acetoin.

†Employee shift lengths varied. For each employee sampled, we sampled for the entire shift.

recommendations presented in this report for the flavoring chemicals are based on the data 

collected using the OSHA sampling methodology, and not on the experimental canister data. 
Health Hazard Evaluation Report 2016-0120-3307 Page 7

The results for the area air samples taken over the entire work day in two shops using silica 

gel tubes are presented in Table 2. In shop A we found detectable levels of diacetyl and 

quantifiable levels of 2,3-pentanedione. In shop B, we did not find detectable concentrations 

of any of the flavoring chemicals measured.

Table 2. Area air sample concentrations (ppb) of flavoring chemicals*

Location Date Sample 

duration 

(minutes)

Diacetyl 2,3-

pentanedione

2,3-

hexanedione

Acetoin

Shop A

Back mixing 

station

Day 1 519 [0.4] [1.2] ND ND

Back mixing 

station

Day 2 542 ND 1.4 ND ND

End of counter Day 1 518 [0.4] 1.3 ND ND

End of counter Day 2 537 ND 1.4 ND ND

Shop B

Behind counter Day 1 539 ND ND ND ND

Behind counter Day 2 541 ND ND ND ND

End of counter Day 1 551 ND ND ND ND

End of counter Day 2 546 ND ND ND ND

*The minimum detectable concentration ranged from 0.3–0.4 ppb for diacetyl and 2,3-pentanedione, 

from 0.4–0.6 parts ppb for 2,3-hexanedione, and from 1.4–1.9 for acetoin. The minimum 

quantifiable concentration for ranged from 1.0–1.3 ppb for diacetyl and 2,3-pentanedione.

[ ] = Estimated concentration; this concentration was between the minimum detectable and 

minimum quantifiable concentrations.

Table 3 presents the personal air sampling results for formaldehyde. All sample results 

were below the OSHA PEL for formaldehyde. Two employees in shop A had formaldehyde 

exposures at or just above the NIOSH REL of 16 ppb. None of the other employees we 

monitored in shop A and none of the employees at shop B had exposures to formaldehyde 

at or above OELs. In general, personal formaldehyde concentrations in shop A were slightly 

higher than concentrations in shop B.
Page 8 Health Hazard Evaluation Report 2016-0120-3307

Table 3. Personal air sample results for formaldehyde

Employee Date Location Sample 

duration 

(minutes)*

Formaldehyde 

(ppb)

1 Day 1 Shop A 447 14

1 Day 2 Shop A 502 14

2 Day 1 Shop A 406 12

3 Day 1 Shop A 501 11

4 Day 1 Shop A 493 15

4 Day 2 Shop A 443 3.6

5 Day 1 Shop A 485 17

5 Day 2 Shop A 562 5.9

6 Day 2 Shop A 549 7.1

7 Day 2 Shop A 543 16

8 Day 1 Shop B 565 3.3

8 Day 2 Shop B 570 6.8

9 Day 1 Shop B 563 4.9

10 Day 2 Shop B 575 6.2

11 Day 2 Shop B 571 6.3

NIOSH REL 16

OSHA PEL 750

*Employee shift lengths varied. For each employee sampled, we sampled for their entire shift.

Table 4 presents the area air sample results for formaldehyde. For both shops, concentrations of 

formaldehyde in the air were generally low and similar to those found in the personal air samples.

Table 4. Area air sample results (ppb) for formaldehyde

Location Date Sample duration 

(minutes)

Formaldehyde 

(ppb)

Shop A - Back mixing station Day 2 521 16

Shop A - End of counter Day 2 516 17

Shop B - Behind counter Day 1 385 3.4

Shop B - Behind counter Day 2 545 6.1

Shop B - End of counter Day 1 385 4.9

Shop B - End of counter Day 2 546 6.1
Health Hazard Evaluation Report 2016-0120-3307 Page 9

Nicotine in Air

Table 5 presents the results for the nicotine area air samples. With the exception of one 

nondetectable sample in shop B, all of the airborne nicotine concentrations were detectable, 

but below the minimum quantifiable concentration. 

Table 5. Area air sample results for nicotine

Location Date Sample duration 

(minutes)

Nicotine (micrograms per 

cubic meter [μg/m3])*

Shop A - Back mixing station Day 1 520 [1.4]

Shop A - Back mixing station Day 2 532 [3.7]

Shop A - End of counter Day 1 524 [2.1]

Shop A - End of counter Day 2 522 [3.5]

Shop B - Behind counter Day 1 563 [0.8]

Shop B - Behind counter Day 2 562 [1.8]

Shop B - End of counter Day 1 557 ND

Shop B - End of counter Day 2 545 [1.1]

[ ] = Estimated concentration; this concentration was between the minimum detectable and 

minimum quantifiable concentrations.

*The minimum detectable concentration range was 0.5–0.6 μg/m3, while the minimum quantifiable 

concentration range was 11–13 μg/m3.

Volatile Organic Compounds in Air

Laboratory analysis of the personal air samples collected using evacuated canisters indicated 

the presence of multiple chemicals. Quantifiable concentrations of ethanol (220–4,000 ppb), 

acetone (ND–60 ppb), isopropyl alcohol (100–400 ppb), limonene ([3.3]–32 ppb), and 

benzene (ND–3.7 ppb) were identified in some of the samples. Detectable, but not quantifiable, 

concentrations of toluene, ethylbenzene, m,p-xylene, o-xylene, and alpha-pinene were also 

identified. Employees’ exposures to all of the compounds identified were well below OELs. 

For the area samples, we identified quantifiable concentrations of acetone (ND–49 ppb), 

benzene (ND–11 ppb), limonene (ND–21 ppb), ethanol (160–1,400 ppb), ethylbenzene 

(ND–4.9 ppb), isopropyl alcohol (90–2,300 ppb), m,p-xylene (ND–6.4 ppb), methyl 

methacrylate (ND–15.5 ppb), o-xylene (ND–3.6 ppb), and toluene (ND–5.8 ppb). Detectable, 

but not quantifiable, concentrations of methylene chloride were also identified.

In addition to the VOCs quantified, 41 other chemicals were tentatively identified in the personal 

and area canister air samples. This included substances on the Flavor and Extract Manufacturers 

Association of the United States (FEMA) list of substances that “may pose potential respiratory 

hazards when improperly handled” [FEMA 2012]. We tentatively identified benzaldehyde, 

furfural, and isobutyraldehyde in our samples. FEMA classifies these chemicals as “high priority” 

substances. Pyridine, ethyl acetate, isoamyl acetate, dimethyl disulfide, and isobutyl acetate were 

also tentatively identified. FEMA classifies these as “low priority” substances. These priority 

levels were assigned by FEMA based on “available inhalation exposure data in animals and 

humans, chemical structure, volatility, and volume of use.”
Page 10 Health Hazard Evaluation Report 2016-0120-3307

Elements on Surfaces

We took surface wipe samples for minerals and metals throughout both vape shops over 

2 days of sampling in each shop. This included surfaces that employees or customers 

touched and included the employee and patron sides of the mixing counters, top of the 

repair counters, and breakroom lunch tabletops. Quantifiable concentrations of aluminum, 

calcium, chromium, copper, iron, lithium, magnesium, manganese, nickel, potassium, 

silver, strontium, tin, and zirconium were identified in the wipe samples. Detectable, but not 

quantifiable, concentrations of barium, indium, tellurium, titanium, yttrium, and zinc were 

also identified in some samples. 

Nicotine on Surfaces

We took surface wipe samples for nicotine throughout both vape shops over 2 days of 

sampling in each shop. For both shops, we sampled surfaces at the nicotine mixing area, on 

the mixing counter, the online mixing counter in the back of the shop, the break room 

mixing bar, the repair counter, and the table used by customers. The laboratory was not able 

to achieve an adequate recovery for the sampling media we used and was not able to 

calculate a limit of quantitation for these data. All but one of the surfaces sampled had 

detectable levels of nicotine at concentrations greater than 0.1 micrograms per 100 square 

centimeters. The table used by customers had a nondetectable level of nicotine on it. There 

are no OELs for dermal exposure to nicotine.

Confidential Employee Interviews

Of 16 employees working during the dates of our visit, 15 participated in the interviews and 

one employee declined. Fourteen were male, and one was female. The median age was 31 

years (range: 21–44 years). 

Employees worked at this company for a median of 17 months (range: 1–56 months). Ten 

employees worked at shop A, four worked at shop B, and one worked at both shops. Two 

employees had previously worked at another vape shop. Employees reported working a 

median of 42.5 hours per week (range: 36–50 hours). 

Of 15 employees, 13 reported mixing e-liquid as part of their job duties. Table 6 shows the 

types of tasks and personal protective equipment (PPE) used while mixing e-liquids that 

employees reported. All 13 employees reported 100 milligrams per milliliter (mg/mL) as the 

highest concentration of nicotine that they had handled. 
Health Hazard Evaluation Report 2016-0120-3307 Page 11

Table 6. Type of job duties and reported PPE use when 

mixing e-liquids (n = 13) 

Type of job duty or PPE Number (%) of employees

Cleaning equipment 12 (92)

Cleaning work surfaces 12 (92)

Gloves, always 13 (100)

Closed toe shoes, always 13 (100)

Long pants 

Always 8 (62)

Sometimes 5 (38)

Table 7 presents the number of employees who reported receiving training on various safety 

topics. All interviewed employees reported receiving training on how to handle liquid 

nicotine safely. Most reported having received training related to liquid nicotine or flavorings.

Table 7. Health and safety training received by interviewed employees (n = 15)

Type of training Number (%) of employees

How to handle liquid nicotine safely 15 (100)

How to clean up spills of liquid nicotine or e-liquid 14 (93)

Types of PPE required for job duties 14 (93)

What to do if liquid nicotine or e-liquid gets into eyes, mouth, 

or skin 12 (80)

Health risks related to work with liquid nicotine 12 (80)

Health risk related to work with flavorings 14 (93)

Six of 13 employees who mix e-liquid reported ever having liquid nicotine or e-liquid 

coming into contact with their skin, eyes, or mouth while mixing e-liquid. Four employees 

reported they had two to five episodes of contact within the past month. We asked for details 

about these recent incidents. All four employees reported wearing gloves, but the liquid 

nicotine or e-liquid came into contact with their wrist or forearm above the glove. Three 

employees reported the contact occurred when there was dripping when they were trying to 

quickly transfer liquid from the dropper. One employee reported splashing liquid nicotine 

onto the forearm while pouring from one bottle to another without using a funnel. All four 

employees reported that they were able to wash the affected area right away and did not have 

any symptoms associated with coming into contact with liquid nicotine or e-liquid. 

Four employees reported liquid nicotine or e-liquid coming into contact with their skin or eyes 

during other job tasks. One employee reported spilling concentrated nicotine 

(100 mg/mL) on his arm while filling a container more than a year ago. He reported sweating 

and feeling “jittery” after the incident. One employee reported liquid nicotine coming into 

contact with his wrist above the glove when he was handling a leaking bottle of liquid nicotine. 

One employee reported hot e-liquid splashing into his eye while he was inspecting a customer’s 
Page 12 Health Hazard Evaluation Report 2016-0120-3307

nonfunctioning e-cigarette. He was not wearing safety glasses at the time. He washed his eye 

in a sink for 3 minutes. He experienced eye burning and redness for approximately 30 minutes, 

with no changes in his vision. Another employee reported contact with e-liquid on multiple 

occasions. He reported getting e-liquid on his ungloved hands approximately 75%–80% of the 

time when inspecting customers’ e-cigarettes. He also reported e-liquid splashing into his ear 

twice in the past month when he held an e-cigarette tester next to his ear to listen for a popping 

sound that indicated it was ready for customer use. 

Fourteen of the 15 interviewed employees reported vaping every day at work. One employee 

is a former vaper. Employees reported using a median of 10 mL (range: 4–30 mL) of e-liquid 

at work, which corresponds to approximately 60% (range: 40%–100%) of their daily e-liquid 

use. Ten employees reported demonstrating how to vape for customers by actually vaping 

themselves. Thirteen employees reported that it gets cloudy or hazy when others are vaping 

around them at work. None of the employees reported currently smoking.

One employee reported eye irritation when working with cinnamon or menthol flavorings in 

the past 4 weeks. None of the employees reported symptoms related to nicotine toxicity, such 

as nausea, vomiting, racing or irregular heartbeat, dizziness, and increased salivation in the 

past 4 weeks. None of the employees reported respiratory symptoms such as cough, shortness 

of breath, chest tightness, or wheezing in the past 4 weeks that might raise suspicion 

for flavorings-related disease. One employee reported currently having asthma that was 

diagnosed by a healthcare provider, but asthma symptoms were not worse while at work.

Discussion

None of the airborne concentrations of the specific flavoring chemicals we measured were 

above applicable OELs using the OSHA sampling methodology. In addition to the OSHA 

sampling methodology, we also tested the use of the evacuated canisters to measure flavoring 

compounds in the air. At present, this canister method is partially validated [LeBouf et al. 

2012] and not considered the standard method. Some employees wore a silica gel tube and an 

evacuated canister at the same time. The concentrations measured by the evacuated canister 

tended to be higher than corresponding concentrations measured by the OSHA silica gel tube 

method (Table A1). In the area samples collected, we similarly observed that the canisters 

measured higher concentrations of the flavoring chemicals than did the OSHA silica gel tube 

method (Table A2). 

Personal air sampling results for formaldehyde, a breakdown product of propylene glycol, 

were well below the OSHA PEL and OSHA action level. Most samples were also below the 

NIOSH REL, which is much lower than the OSHA PEL. NIOSH recognized formaldehyde 

as a potential occupational carcinogen in 1981 and, following the NIOSH carcinogen policy 

in existence at the time, set the REL to the “lowest feasible concentration,” which for 

formaldehyde was defined as the analytical limit of quantification of 16 ppb for up to 8 hours 

[NIOSH 1981]. Since then, experience has shown that this REL is actually not the “lowest 

feasible concentration” because formaldehyde in the ambient air can exceed 16 ppb, a fact 

NIOSH has acknowledged [Lemen 1987]. Area sampling results showed that background 

formaldehyde concentrations were similar to the personal sampling results and that shop 
Health Hazard Evaluation Report 2016-0120-3307 Page 13

B generally had lower formaldehyde concentrations than shop A. Low concentrations of 

formaldehyde exist in many indoor environments because of off gassing from furnishings, 

clothing, and other materials.

In addition to the specific flavoring chemicals we looked for in the air samples (diacetyl, 

2,3-pentanedione, 2,3-hexanedione, and acetoin), we also identified other flavoring chemicals 

and VOCs in the air of the vape shops. Results from the air samples we collected using 

evacuated canisters showed very low concentrations of chemicals found in cleaning products 

(limonene, isopropanol), as well as other chemicals that could be classified as flavoring 

chemicals. Some of the flavoring chemicals found were on the FEMA list of substances 

that “may pose potential respiratory hazards when improperly handled.” Concentrations of 

nicotine in the air of the shop were also very low. 

Over the 4 days of our evaluation in the two shops, we observed that employees vaped 

throughout the day. Customers also vaped inside of the shop, though the amount they vaped 

varied. Our observations indicate that most of an employee’s exposure to vaping-related 

chemicals inside these vape shops was due to direct inhalation of vaping-related chemicals 

from their personal e-cigarette. They were also exposed to secondhand emissions from 

coworkers’ and patrons’ e-cigarettes. This observation was similar to what we observed in a 

previous health hazard evaluation [NIOSH 2017]. Our air sampling only measured vaping 

chemicals present in the air from the emissions of e-cigarettes and exhaled breath. We did 

not measure chemical concentrations directly inhaled from an employee’s own e-cigarette. 

However, the concentrations of vaping chemicals directly inhaled during vaping would likely 

be higher than the concentrations from secondhand emissions. Although our air sampling 

results showed very low exposures to vaping chemicals, exposure would have been even 

lower if employees had not been vaping in the shop. 

We detected the presence of metals, such as chromium, copper, and nickel on surfaces in the 

shop. This finding was not surprising given that these metals have also been measured by other 

researchers in e-liquids (chromium, nickel) and in vapor from e-cigarettes (chromium, nickel, 

and copper) [Hess et al. 2017; Williams et al. 2013]. Some of the other elements that we detected 

on surfaces are found in human sweat (calcium, potassium, magnesium, and phosphorous). It is 

unknown if their presence on surfaces was from e-cigarettes, people touching surfaces, or both. 

Although most employees reported cleaning equipment and work surfaces for mixing 

e-liquid during the interviews, almost all commonly touched surfaces had detectable levels of 

nicotine, suggesting that housekeeping processes can be improved. In addition, it is important 

to use good chemical handling procedures whenever working with nicotine, especially the 

stock nicotine solution. 

Nicotine is a potent and potentially lethal toxin that is quickly absorbed from all routes of entry, 

including the skin or eyes [Brandon et al. 2015]. Exposure to nicotine can occur by inhalation, 

skin absorption, and ingestion. If nicotine gets on the skin, employees should immediately wash 

the affected area with soap and water. Research has shown that it only takes 3 to 5 minutes for 

nicotine to be absorbed through the skin [Zorin et al. 1999]; after that length of time, nicotine 

cannot be washed off and remains in the skin where it continues to be absorbed into the body. 

During interviews, employees reported that nicotine or nicotine-containing e-liquid came 
Page 14 Health Hazard Evaluation Report 2016-0120-3307

into contact with their skin or eyes. All four employees who reported exposures while 

mixing e-liquid in the last month stated that skin exposure occurred on uncovered wrists or 

forearms, despite wearing gloves as required. None of these employees reported symptoms 

consistent with nicotine toxicity; however, an employee reported symptoms consistent with 

nicotine exposure after skin contact from concentrated nicotine spilling on his arm during an 

earlier incident. Longer gloves or sleeves covering the arms could minimize the likelihood 

of this type of skin contact. Most employees reported receiving training on how to clean up 

spills and what to do if nicotine or e-liquid gets into their eyes, mouth, or skin. Inspecting 

customers’ e-cigarettes without gloves and verifying that an e-cigarette tester was ready for 

use were identified as other tasks where employees might have skin and eye exposure to 

nicotine. Ways to reduce nicotine exposures to employees during these tasks include finding 

another way to tell if an e-cigarette tester is ready and wearing gloves and eye protection. 

Few standards define “acceptable” levels of workplace surface contamination. Wipe samples, 

however, can provide information regarding the effectiveness of housekeeping practices, 

the potential for exposure to contaminants by skin absorption or ingestion, the potential for 

contamination of employee clothing and subsequent transport of the contaminant outside 

the workplace, and the potential for other activities (e.g., sweeping) to generate airborne 

contaminants. Overall, we found low levels of some surface contaminants during our evaluation.

The health effects associated with vaping are not well understood. According to the U.S. 

Surgeon General’s report on e-cigarette use among youth and young adults, e-cigarette 

aerosol is not harmless because it contains nicotine, flavorings, other additives, and ultrafine 

particles [DHHS 2016]. The United States Food and Drug Administration has warned 

consumers about potential health risks associated with e-cigarettes and has finalized a rule 

extending their regulatory authority to cover electronic cigarettes [FDA 2013, 2016]. While 

none of the interviewed employees reported respiratory symptoms in the previous 4 weeks, 

flavoring chemicals such as diacetyl and 2,3-pentanedione have been associated with serious 

respiratory disease [NIOSH 2016]. One way to reduce exposure to these chemicals is to not 

use products containing them. Studies have shown that even flavors that are reported as being 

free of diacetyl may still contain it [Allen et al. 2016; Rutledge 2015]. The health risks of 

flavoring chemicals that may be used as substitutes for diacetyl and 2,3-pentanedione may 

not be known, and precautionary measures such as engineering controls are recommended to 

protect employees exposed to these substitutes [NIOSH 2016; OSHA 2010b].

This evaluation had limitations that could influence the generalizability of our findings. First, 

sampling occurred over 2 days in each shop during the summer, and our measurement results 

may not be representative of all other times or seasons. Over the 2 days we spent in each shop, 

we observed many employees vaping but we did not observe a large number of customers 

vaping. Most of the customers we observed were in the shop to purchase liquids, and did not 

vape much. Moreover, we do not know the chemical composition of the e-liquids employees 

and customers vaped over the course of our evaluation. The low air concentrations of flavoring 

chemicals that we measured during our evaluation may occur because the e-liquids employees 

and customers used contained low levels of the flavoring compounds we measured. Finally, 

our sampling method for nicotine was not able to capture nicotine that had potentially adsorbed 

onto particulate matter.
Health Hazard Evaluation Report 2016-0120-3307 Page 15

Conclusions

Employees were exposed to low levels of flavoring chemicals in the air while working in 

the vape shops. Although the measured concentrations were below all applicable OELs, to 

better protect the health of employees, we recommend that the employer implement a policy 

prohibiting vaping in the workplace with e-liquids that contain diacetyl and 2,3-pentanedione. 

Some employees reported liquid nicotine or e-liquid coming into contact with their skin and 

eyes. Analyzing which work tasks are associated with nicotine exposure to identify PPE needs, 

training employees on proper chemical handling procedures, and ensuring consistent use of 

chemical protective nitrile gloves when handling liquids containing nicotine or customers’ 

e-cigarettes will likely reduce employees’ work-related exposure to nicotine.

Recommendations

On the basis of our findings, we recommend the actions listed below. We encourage the vape 

shops to use an employee-employer health and safety committee or working group to discuss our 

recommendations and develop an action plan. Those involved in the work can best set priorities 

and assess the feasibility of our recommendations for the specific situation at the vape shops. 

Our recommendations are based on an approach known as the hierarchy of controls (Appendix 

B). This approach groups actions by their likely effectiveness in reducing or removing hazards. 

In most cases, the preferred approach is to eliminate hazardous materials or processes and 

install engineering controls to reduce exposure or shield employees. Until such controls are in 

place, or if they are not effective or feasible, administrative measures and PPE may be needed.

Elimination and Substitution

Eliminating or substituting hazardous processes or materials reduces hazards and protects 

employees more effectively than other approaches. Prevention through design, considering 

elimination or substitution when designing or developing a project, reduces the need for 

additional controls in the future.

1. Implement a policy prohibiting vaping in the shop with e-liquids that contain diacetyl 

and 2,3-pentanedione.

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. Fix the large carboys containing nicotine, propylene glycol, and vegetable glycerin to 

ensure that they do not leak.

2. Replace the broken and leaking caps on transfer bottles of flavorings, nicotine, and 

other chemicals so that they do not leak.

3. Install secondary containment underneath the carboys so that if spills or leaks occur, 
Page 16 Health Hazard Evaluation Report 2016-0120-3307

the chemical can be easily contained and cleaned up. This could consist of a small spill 

tray or drip pan that will prevent the leaking material from splashing on the counters 

below the carboys.

Administrative Controls

The term administrative controls refers to employer-dictated work practices and policies 

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. Instruct employees to immediately use soap and water to wash skin that comes into 

contact with nicotine. Nicotine is absorbed through the skin in only 3 to 5 minutes; 

after that, the nicotine cannot be washed off [Zorin et al. 1999].

2. Train employees on the potential hazards in the vaping industry such as flavorings, nicotine, 

and formaldehyde and how to protect themselves. The OSHA hazard communication 

standard [29 CFR 1910.1200] requires that employees are informed and trained on potential 

work hazards and associated safe practices, procedures, and protective measures.

3. Instruct employees to clean their stations and other commonly touched surfaces 

throughout the day to prevent accumulation of nicotine on them.

4. Review current work practices and update current PPE policies to prevent skin 

exposure to nicotine.

5. Label on all secondary containers used to store flavorings and nicotine. The labels must 

meet the requirements of the OSHA hazard communication standard, https://www.osha.

gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10099.

Personal Protective Equipment

Proper use of PPE requires a comprehensive program and a high level of employee 

involvement and commitment. The right PPE must be chosen for each hazard. Supporting 

programs such as training, change-out schedules, and medical assessment may be needed. 

PPE should not be the sole method for controlling hazardous exposures. Rather, PPE should 

be used until effective engineering and administrative controls are in place.

1. Train employees and require them to wear chemical protective gloves made out of nitrile 

whenever working with nicotine. This should include activities such as mixing e-liquids, 

filling transfer bottles, and handling customers’ e-cigarettes. Because nicotine can break 

through the glove material in as little as 6 to 9 minutes, employees should not reuse gloves 

and should use a new pair of gloves each time they start a new task involving nicotine.

2. Provide long-sleeved lab coats and goggles or face shields and instruct employees 

on their use to prevent contact with the eyes, skin, or clothing when handling the 

stock nicotine solution, such as when transferring from the stock solution container 

to another container. Gloves with a longer cuff could be used to help protect against 

nicotine spills on the wrist and forearm for employees mixing e-liquids.
Health Hazard Evaluation Report 2016-0120-3307 Page 17

Table A1. Personal air sampling results for flavoring chemicals using evacuated canisters (ppb)*

Employee Date Sample 

duration 

(minutes)†

Diacetyl 2,3-

pentanedione

2,3-

hexanedione

Acetaldehyde

Shop A

1 Day 1 479 [2.4] [2.3] ND ND

4 Day 1 431 3.3 4.3 ND ND

5 Day 1 398 [2.9] [2.8] ND ND

5 Day 2 588 [2.3] [2.6] ND ND

6 Day 2 595 [3.7] [5.1] ND ND

7 Day 2 558 4.4 4.7 [3] ND

Shop B

8 Day 1 495 [1.4] [1.4] ND ND

8 Day 2 589 [2.5] [2.1] ND ND

9 Day 1 572 [1.5] ND ND ND

10 Day 2 589 [2] ND ND ND

11‡ Day 2 577 ND ND ND ND

ACGIH TLV 10 — — —

NIOSH REL 5.0 9.3 — —

OSHA PEL — — — —

[ ] = Estimated concentration; this concentration was between the minimum detectable and 

minimum quantifiable concentrations.

*For employees 1–10, the minimum detectable concentration range was 1–2 ppb for diacetyl and 

acetaldehyde, 1–3 ppb for 2,3-pentanedione, and 2–5 ppb for 2,3-hexanedione. The minimum 

quantifiable concentration range was 2.6–6.7 ppb for diacetyl, 3.6–9.3 ppb for 2,3-pentanedione, 

and 6.4–17 ppb for 2,3-hexanedione. 

†Employee shift lengths varied. For each employee sampled, we sampled for their entire shift.

‡Employee 11’s minimum detectable concentrations were substantially higher than other samples 

due to an excess of ethanol in the sample. The minimum detectable concentration was 10 ppb for 

diacetyl, 2,3-pentanedione, and acetaldehyde, and 20 ppb for 2,3-hexanedione.

Appendix A: Tables
Page 18 Health Hazard Evaluation Report 2016-0120-3307

Table A2. Area air sample concentrations of flavoring chemicals using evacuated canisters (ppb)*

Location Date Sample 

duration 

(minutes)

Diacetyl 2,3-

pentanedione

2,3-

hexanedione

Acetaldehyde

Shop A

Back mixing 

station

Day 1 521 5.9 [4.5] ND ND

Back mixing 

station

Day 2 542 [2.9] [2.9] ND ND

End of 

counter

Day 1 527 [3.5] [1.8] ND ND

End of 

counter

Day 2 537 12.5 21.2 18 ND

Shop B

End of 

counter

Day 1 556 [2.7] [2.6] ND ND

End of 

counter

Day 2 546 [1.3] [1.6] ND ND

Behind 

counter

Day 1 554 4.1 [3.9] ND ND

Behind 

counter

Day 2 542 [2.6] [2.9] ND ND

[ ] = Estimated concentration; this concentration was between the minimum detectable and 

minimum quantifiable concentrations.

*The minimum detectable concentration was 1 ppb for diacetyl and acetaldehyde, 1–2 ppb for 

2,3-pentanedione, and 2–3 ppb for 2,3-hexanedione. The minimum quantifiable concentration 

range was 3.2–4.6 ppb for diacetyl and 4.5–6.4 ppb for 2,3-pentanedione.
Health Hazard Evaluation Report 2016-0120-3307 Page 19

Appendix B: Occupational Exposure Limits and 

Health Effects

NIOSH investigators refer to mandatory (legally enforceable) and recommended OELs for 

chemical, physical, and biological agents when evaluating workplace hazards. OELs have 

been developed by federal agencies and safety and health organizations to prevent adverse 

health effects from workplace exposures. Generally, OELs suggest levels of exposure that 

most employees may be exposed to for up to 10 hours per day, 40 hours per week, for a 

working lifetime, without experiencing adverse health effects. However, not all employees 

will be protected if their exposures are maintained below these levels. Some may have 

adverse health effects because of individual susceptibility, a pre-existing medical condition, 

or a hypersensitivity (allergy). In addition, some hazardous substances act in combination 

with other exposures, with the general environment, or with medications or personal habits 

of the employee to produce adverse health effects. Most OELs address airborne exposures, 

but some substances can be absorbed directly through the skin and mucous membranes.

Most OELs are expressed as a TWA exposure. A TWA refers to the average exposure during 

a normal 8- to 10-hour workday. Some chemical substances and physical agents have 

recommended short-term exposure limits (STEL) or ceiling values. Unless otherwise noted, 

the STEL is a 15-minute TWA exposure. It should not be exceeded at any time during a 

workday. The ceiling limit should not be exceeded at any time.

In the United States, OELs have been established by federal agencies, professional 

organizations, state and local governments, and other entities. Some OELs are legally 

enforceable limits; others are recommendations. 

● The U.S. Department of Labor OSHA PELs (29 CFR 1910 [general industry]; 29 CFR 

1926 [construction industry]; and 29 CFR 1917 [maritime industry]) are legal limits. 

These limits are enforceable in workplaces covered under the Occupational Safety and 

Health Act of 1970. 

● NIOSH RELs are recommendations based on a critical review of the scientific and 

technical information and the adequacy of methods to identify and control the hazard. 

NIOSH RELs are published in the NIOSH Pocket Guide to Chemical Hazards [NIOSH 

2010]. NIOSH also recommends risk management practices (e.g., engineering controls, 

safe work practices, employee education/training, PPE, and exposure and medical 

monitoring) to minimize the risk of exposure and adverse health effects.

● Another set of OELs commonly used and cited in the United States is the ACGIH 

TLVs. The TLVs are developed by committee members of this professional 

organization from a review of the published, peer-reviewed literature. TLVs are not 

consensus standards. They are considered voluntary exposure guidelines for use by 

industrial hygienists and others trained in this discipline “to assist in the control of 

health hazards” [ACGIH 2017].
Page 20 Health Hazard Evaluation Report 2016-0120-3307

Outside the United States, OELs have been established by various agencies and organizations 

and include legal and recommended limits. The Institut für Arbeitsschutz der Deutschen 

Gesetzlichen Unfallversicherung (Institute for Occupational Safety and Health of the German 

Social Accident Insurance) maintains a database of international OELs from European Union 

member states, Canada (Québec), Japan, Switzerland, and the United States. The database, 

available at http://www.dguv.de/ifa/GESTIS/GESTIS-Internationale-Grenzwerte-fürchemische-Substanzen-limit-values-for-chemical-agents/index-2.jsp, contains international 

limits for more than 2,000 hazardous substances and is updated periodically. 

OSHA requires an employer to furnish employees a place of employment free from 

recognized hazards that cause or are likely to cause death or serious physical harm 

[Occupational Safety and Health Act of 1970 (Public Law 91–596, sec. 5(a)(1))]. This is true 

in the absence of a specific OEL. It also is important to keep in mind that OELs may not 

reflect current health-based information.

When multiple OELs exist for a substance or agent, NIOSH investigators generally 

encourage employers to use the lowest OEL when making risk assessment and risk 

management decisions. NIOSH investigators also encourage use of the hierarchy of controls 

approach to eliminate or minimize workplace hazards. This includes, in order of preference, 

the use of (1) substitution or elimination of the hazardous agent, (2) engineering controls 

(e.g., local exhaust ventilation, process enclosure, dilution ventilation), (3) administrative 

controls (e.g., limiting time of exposure, employee training, work practice changes, medical 

surveillance), and (4) PPE (e.g., respiratory protection, gloves, eye protection, hearing 

protection). Control banding, a qualitative risk assessment and risk management tool, is a 

complementary approach to protecting employee health. Control banding focuses on how 

broad categories of risk should be managed. Information on control banding is available at 

http://www.cdc.gov/niosh/topics/ctrlbanding/. This approach can be applied in situations 

where OELs have not been established or can be used to supplement existing OELs.

Diacetyl and 2,3-pentanedione

Diacetyl (2,3-butanedione) and 2,3-pentanedione, a diacetyl substitute, are VOCs with an 

intense buttery flavor. Exposure to diacetyl is associated with an increased risk for severe 

lung disease and lung function decline [NIOSH 2016]. Irreversible lung disease, such 

as obliterative bronchiolitis, has been reported in employees in industries with diacetyl 

exposures [Kreiss 2007; van Rooy et al. 2007]. Severe airway damage and disease has also 

been observed in laboratory animals after exposure to diacetyl or 2,3-pentanedione [Hubbs et 

al. 2008; Morgan et al. 2012]. Because of the potential health effects associated with diacetyl 

and 2,3-pentanedione exposure, NIOSH has a REL and 15-minute STEL for both of these 

flavoring chemicals. 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 a guideline to indicate when steps should be 

taken to reduce exposures in the workplace. The NIOSH REL is 5 ppb for diacetyl with 
Health Hazard Evaluation Report 2016-0120-3307 Page 21

a STEL of 25 ppb. NIOSH also has an action level of 2.6 ppb for diacetyl. The REL for 

2,3-pentanedione is 9.3 ppb, and the STEL is 31 ppb [NIOSH 2016]. The higher REL and 

STEL for 2,3-pentanedione does not imply that 2,3-pentanedione is of lower toxicity than 

diacetyl. Rather, the REL and STEL for 2,3-pentanedione are based upon the lowest level at 

which the substance reliably can be detected using the existing validated analytical method 

[NIOSH 2016].
Page 22 Health Hazard Evaluation Report 2016-0120-3307

References

ACGIH [2017]. 2017 TLVs® and BEIs®: threshold limit values for chemical substances and 

physical agents and biological exposure indices. Cincinnati, OH: American Conference of 

Governmental Industrial Hygienists.

AIHA [2014]. White paper: electronic cigarettes in the indoor environment. Falls Church, 

VA: American Industrial Hygiene Association.

Allen JG, Flanigan SS, LeBlanc M, Vallarino J, MacNaughton P, Stewart JH, Christiani DC 

[2016]. Flavoring chemicals in e-cigarettes: diacetyl, 2,3-pentanedione, and acetoin in a 

sample of 51 products, including fruit-, candy-, and cocktail-flavored e-cigarettes. Environ 

Health Perspect 124(6):733–739, http://dx.doi.org/10.1289/ehp.1510185.

CFR. Code of Federal Regulations. Washington, DC: U.S. Government Printing Office, 

Office of the Federal Register.

Brandon TH, Goniewicz ML, Hanna NH, Hatsukami DK, Herbst RS, Hobin JA, Ostroff 

JS, Shields PG, Toll, BA, Tyne CA, Viswanath K, Warren GW [2015]. Electronic nicotine 

delivery systems: a policy statement from the American Association for Cancer Research and 

the American Society of Clinical Oncology. Clin Cancer Res 21(3):514–525, 

http://dx.doi.org/10.1158/1078-0432.CCR-14-2544.

Czogala J, Goniewicz ML, Fidelus B, Zielinska-Danch W, Travers MJ, Sobczak A [2014]. 

Secondhand exposure to vapors from electronic cigarettes. Nicotine Tob Res 16(6):655–662, 

http://dx.doi.org/10.1093/ntr/ntt203.

DHHS [2016]. E-cigarette use among youth and young adults: a report of the Surgeon 

General. Atlanta, GA: U.S. Department of Health and Human Services, Centers for Disease 

Control and Prevention, National Center for Chronic Disease Prevention and Health 

Promotion, Office on Smoking and Health, 

https://e-cigarettes.surgeongeneral.gov/documents/2016_SGR_Full_Report_508.pdf.

FDA [2013]. FDA warns of health risks posed by e-cigarettes, 

https://www.fda.gov/ForConsumers/ConsumerUpdates/ucm173401.htm.

FDA [2016]. Vaporizers, e-cigarettes, and other electronic nicotine delivery systems (ENDS), 

https://www.fda.gov/TobaccoProducts/Labeling/ProductsIngredientsComponents/ucm456610.htm.

FEMA [2012]. Respiratory health and safety in the flavor manufacturing workplace – 2012 

update. Washington, DC: The Flavor and Extract Manufacturers Association of the United States.

Hess CA, Olmedo P, Navas Acien A, Goessler W, Cohen JE, Rule AM [2017]. E-cigarettes 

as a source of toxic and potentially carcinogenic metals. Environ Res 152:221–225, 

http://dx.doi.org/10.1016/j.envres.2016.09.026.
Health Hazard Evaluation Report 2016-0120-3307 Page 23

Hubbs AF, Goldsmith WT, Kashon ML, Frazer D, Mercer RR, Bateeilli LA, Kullman GJ, 

Schwegler-Berry D, Friend S, Castranova V [2008]. Respiratory toxicologic pathology of 

inhaled diacetyl in Sprague-Dawley rats. Toxicol Pathol 36(2):330–344, 

https://dx.doi.org/10.1177/0192623307312694.

Kreiss K [2007]. Flavoring-related bronchiolitis obliterans. Curr Opin Allergy Clin Immunol 

7(2):162–167, https://dx.doi.org/10.1097/ACI.0b013e3280298235.

LeBouf RF, Stefaniak AB, Virji MA [2012]. Validation of evacuated canisters for sampling 

volatile organic compounds in healthcare settings. J Environ Monit 14(3):977–983, 

http://dx.doi.org/10.1039/c2em10896h.

LeBouf RF, Simmons M [2017]. Increased sensitivity of OSHA method analysis of diacetyl 

and 2,3-pentanedione in air. J Occup Environ Hyg 14(5):343–348, 

http://dx.doi.org/10.1080/15459624.2016.1252846.

Lemen RA [1987]. Official letter from R.A. Lemen, Director, Division of Standards 

Development and Technology Transfer, National Institute for Occupational Safety and 

Health, U.S. Department of Health and Human Services, Cincinnati, OH to Tom Hall, Docket 

Office, Department of Labor, Washington, DC, dated February 9.

Maloney JC, Thompson MK, Oldham MJ, Stiff CL, Lilly PD, Patskan GJ, Shafer KH, Sarkar 

MA [2016]. Insights from two industrial hygiene pilot e-cigarette passive vaping studies. 

J Occup Environ Hyg 13(4):275–283, http://dx.doi.org/10.1080/15459624.2015.1116693.

Morgan DL, Jokinen MP, Price HC, Gwinn WM, Palmer SM, Flake GP [2012]. Bronchial 

and bronchiolar fibrosis in rats exposed to 2,3-pentanedione vapors: implications for 

bronchiolitis obliterans in humans. Toxicol Pathol 40(3):448–465, 

https://dx.doi.org/10.1177/0192623311431946.

NIOSH [1981]. Current intelligence bulletin 34 – formaldehyde: evidence of carcinogenicity. 

Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease 

Control, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication 

No. 81-111, https://www.cdc.gov/niosh/docs/81-111/.

NIOSH [2010]. NIOSH pocket guide to chemical hazards. Cincinnati, OH: U.S. Department 

of Health and Human Services, Centers for Disease Control and Prevention, National 

Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 2010-168c, 

http://www.cdc.gov/niosh/npg/. 

NIOSH [2016]. Criteria for a recommended standard: occupational exposure to diacetyl 

and 2,3-pentanedione. Cincinnati, OH: U.S. Department of Health and Human Resources, 

Centers for Disease Control and Prevention, National Institute for Occupational Safety and 

Health, DHHS (NIOSH) Publication No. 2016-111, 

https://www.cdc.gov/niosh/docs/2016-111/pdfs/2016-111-all.pdf.
Page 24 Health Hazard Evaluation Report 2016-0120-3307

NIOSH [2017]. Evaluation of chemical exposures at a vape shop. By Zwack LM, Stefaniak 

AB, LeBouf RF. Cincinnati, OH: U.S. Department of Health and Human Services, Centers 

for Disease Control and Prevention, National Institute for Occupational Safety and Health, 

Health Hazard Evaluation Report 2015-0107-3279, 

http://www.cdc.gov/niosh/hhe/reports/pdfs/2015-0107-3279.pdf.

NIOSH [2018]. NIOSH manual of analytical methods (NMAM). 5th ed. O’Connor PF, 

Ashley K, eds. Cincinnati, OH: U.S. Department of Health and Human Services, Centers 

for Disease Control and Prevention, National Institute for Occupational Safety and Health, 

DHHS (NIOSH) Publication No. 2014-151, http://www.cdc.gov/niosh/nmam.

OSHA [2005]. Sampling and analytical methods: method 1007 – formaldehyde, 

https://www.osha.gov/dts/sltc/methods/mdt/mdt1007/1007.html.

OSHA [2008]. Sampling and analytical methods: method 1013 – acetoin and diacetyl, 

http://www.osha.gov/dts/sltc/methods/validated/1013/1013.html. 

OSHA [2010a]. Sampling and analytical methods: method 1016 – 2,3-pentanedione, 

http://www.osha.gov/dts/sltc/methods/validated/1016/1016.html. 

OSHA [2010b]. Occupational exposure to flavoring substances: health effects and hazard 

control, https://www.osha.gov/dts/shib/shib10142010.html.

Rutledge R [2015]. Gasping for action: lab tests reveal popular e-cigarette liquids contain 

harmful chemicals. Milwaukee Journal Sentinel, October 20, 

http://archive.jsonline.com/watchdog/watchdogreports/lab-tests-reveal-popular-e-cigaretteliquids-contain-harmful-chemicals-b99583582z1-334833961.html.

Schober W, Szendrei K, Matzen W, Osiander-Fuchs H, Heitmann D, Schettgen T, Jörres RA, 

Fromme H [2014]. Use of electronic cigarettes (e-cigarettes) impairs indoor air quality and 

increases FeNO levels of e-cigarette consumers. Int J Hyg Environ Health 217(6):628–637, 

http://dx.doi.org/10.1016/j.ijheh.2013.11.003.

Schripp T, Markewitz D, Uhde E, Salthammer T [2013]. Does e-cigarette consumption cause 

passive vaping? Indoor Air 23(1):25–31, http://dx.doi.org/10.1111/j.1600-0668.2012.00792.x.

van Rooy FG, Rooyackers JM, Prokop M, Houba R, Smit LAM, Heederik D [2007]. 

Bronchiolitis obliterans symdrome in chemical employees producing diacetyl for food flavorings. 

Am J Respir Crit Care Med 176(5):498–504, http://dx.doi.org/10.1164/rccm.200611-1620OC.

Williams M, Villarreal A, Bozhilov K, Lin S, Talbot P [2013]. Metal and silicate particles 

including nanoparticles are present in electronic cigarette cartomizer fluid and aerosol. PLOS 

ONE 8(3):1–11, http://dx.doi.org/10.1371/journal.pone.0057987.

Zorin S, Kuylenstierna F, Thulin H [1999]. In vitro test of nicotine’s permeability through 

human skin. Risk evaluation and safety aspects. Ann Occup Hyg 43(6):405–413, 

http://dx.doi.org/10.1093/annhyg/43.6.405.
Health Hazard Evaluation Report 2016-0120-3307 Page 25

Keywords: North American Industry Classification System (NAICS) 453991 (Tobacco 

Stores), Texas, Vaping, E-Cigarette, Diacetyl, 2,3-Pentanedione, 2,3-Hexanedione, 

Formaldehyde, Nicotine, Metals, Propylene Glycol, Acetaldehyde, Acetoin, VOCs, Vape 

Shop, Flavorings
Page 26 Health Hazard Evaluation Report 2016-0120-3307

This page left intentionally blank
Health Hazard Evaluation Report 2016-0120-3307 Page 27

The Health Hazard Evaluation Program investigates possible health hazards in the workplace 

under the authority of the Occupational Safety and Health Act of 1970 (29 U.S.C. § 669(a)

(6)). The Health Hazard Evaluation Program also provides, upon request, technical assistance 

to federal, state, and local agencies to investigate occupational health hazards and to prevent 

occupational disease or injury. Regulations guiding the Program can be found in Title 42, Code 

of Federal Regulations, Part 85; Requests for Health Hazard Evaluations (42 CFR Part 85).

Disclaimer

The recommendations in this report are made on the basis of the findings at the workplace 

evaluated and may not be applicable to other workplaces.

Mention of any company or product in this report does not constitute endorsement by NIOSH.

Citations to Web sites external to NIOSH do not constitute NIOSH endorsement of the 

sponsoring organizations or their programs or products. NIOSH is not responsible for the 

content of these Web sites. All Web addresses referenced in this document were accessible as of 

the publication date.

Acknowledgments

Analytical Support: Maxxam Analytics

Desktop Publisher: Shawna Watts 

Editor: Ellen Galloway 

Industrial Hygiene Field Assistance: Matthew Duling, Stephen Jackson

Logistics: Donnie Booher, Kevin Moore, Emily Hall, Heidi Bojes

Availability of Report

Copies of this report have been sent to the employer and employees at the facility. The state and 

local health department and the Occupational Safety and Health Administration Regional Office 

have also received a copy. This report is not copyrighted and may be freely reproduced. 

Recommended citation for this report:

NIOSH [2018]. Evaluation of chemical exposures at two vape shops in Texas. By 

Zwack LM, Chiu S, LeBouf RF. Cincinnati, OH: U.S. Department of Health and 

Human Services, Centers for Disease Control and Prevention, National Institute for 

Occupational Safety and Health, Health Hazard Evaluation Report 2016-0120-3307, 

http://www.cdc.gov/niosh/hhe/reports/pdfs/2016-0120-3307.pdf.
To receive NIOSH documents or more information about 

occupational safety and health topics, please contact NIOSH:

Telephone: 1–800–CDC–INFO (1–800–232–4636)

TTY: 1–888–232–6348

CDC INFO: www.cdc.gov/info

or visit the NIOSH Web site at www.cdc.gov/niosh

For a monthly update on news at NIOSH, subscribe to 

NIOSH eNews by visiting www.cdc.gov/niosh/eNews.

Delivering on the Nation’s promise:

Promoting productive workplaces through safety and health research