Industrial Hygiene 

Exposure Control

William P. Robert 

BASF Corporation
2

Overview

• Possible Anticipated Exposures

• Considerations for Controlling Exposure

• Isocyanate Neutralization and 

Decontamination

• Dermal Protection Considerations

• Respiratory Protection Considerations

• Conclusion
3

Possible Anticipated Exposures

• Respiratory Exposure (TDI / MDI)

– Process conditions such as heating or 

atomization (e.g., spraying)

– Poor ventilation

– Sawing / sanding / grinding parts

– Thermal degradation
4

Possible Anticipated Exposures

• Possible Dermal Exposure

– Handling liquid isocyanate

– Open pouring (e.g., molding)

– Incomplete cure (e.g., off ratio molding)

– Cleaning equipment

– Exposure to contaminated surfaces 
5

Possible Anticipated Exposures

• Possible Ingestion

– Swallowing isocyanates

• Eating or drinking in work station

• Smoking or using other tobacco products near 

isocyanates
6

Considerations for Controlling 

Exposure

• Engineering

– Providing adequate ventilation when working in an 

enclosed area (e.g., spray booth).

– Having hand wash stations or showers available in 

work area.

– Decontaminating surfaces that have come into 

contact with isocyanates.
7

Considerations for Controlling 

Exposure

• Personal Protective Equipment

– Chemical worker‟s goggles

– MDI or TDI-resistant long-sleeve coveralls or full 

body suits

– MDI or TDI-resistant fitted boots 

– Head protection, such as a close-fitting hood

– Air respirator or air-purifying respirator (consult 

your MSDS for guidance)
8

Considerations for Controlling 

Exposure

• Administration

– Controlling unauthorized or unprotected employee 

access to exposure areas.

– Training workers and staff on how to handle 

isocyanates.

– Conducting medical examinations of workers who 

will be handling isocyanates.

– Making material data safety sheets (MSDS) and other 

training materials available to persons working with 

isocyanates.
9

Isocyanate Neutralization and 

Decontamination- Surfaces

• Surface Contamination 

Assessment

• Methods for detection 

of isocyanates may 

include:

– Colorimetric swipes

– Turn red on contact with 

isocyanate

– Good for housekeeping check, 

employee training
10

Isocyanate Neutralization and 

Decontamination- Surfaces

• Neutralization means 

treating MDI or TDI with 

solid or liquid 

neutralizer to destroy 

the isocyanate groups 

and minimize exposure. 

• Decontamination means 

removing all detectable 

traces of diisocyanate

from a given surface or 

area. 
11

Isocyanate Neutralization and 

Decontamination- Surfaces

• Isocyanates react to form inert solids with:

– Alcohols

– Amines

– Water (slow reaction)

• Therefore, the basis for decontamination 

solutions usually include alcohol or amine in 

water solutions with surfactants

– Water – main reactant

– Amine/ Ammonia – catalyst

– Surfactant – surface tension breaker (greater contact 

between the water and the isocyanate)
12

Dermal Exposure Considerations

• Available data includes:

– API Technical Bulletin 178 – PMDI User 

Guidelines for Protective Clothing Selection

– API Technical Bulletin 179-TDI User 

Guidelines for Protective Clothing Selection

– Polyurethanes Expo 1999 Proceedings – paper 

by Robert and Hayward
13

Respiratory Protection Considerations

• Air purifying respirators (APRs)

• Supplied air respirators (SARs)
14

Respiratory Protection- APR

• Three types of Air 

Purifying Respirators:

– Full-face

– Half-face

– Powered APR

• Select cartridge type 

based on chemical 

and physical form of 

hazards present
15

Respiratory Protection- APR

• Select APR cartridge based on chemical and physical 

form of diisocyanates present:

• Consider organic vapor & particulate (OV/P100) 

APR Cartridge for MDI;Use Organic Vapor 

Cartridge for TDI
Industrial Hygiene 

Monitoring for 

Diisocyanates

William P. Robert 

BASF Corporation
17

Overview

• Why monitor for diisocyanates?

• Exposure evaluation

• Types of monitoring

• Summary of Product Stewardship 

monitoring in various industries

• Conclusion
18

Why monitor for diisocyanates?

• Why establish a monitoring program for 

diisocyanates?

– To assess and reduce the potential for 

workplace and community exposure

– Monitor airborne releases (e.g., spills, stack, 

etc.) from the site to identify and reduce 

exposures to the community or environment

– Compliance with regulatory requirements
19

Why monitor for diisocyanates?

• Workplace monitoring can be effective 

when conducted periodically, and, when 

there is the following:

– Reported health effect

– New process or product

– Change to existing equipment/process

– Suspected leak

– Spill or release 
20

Why monitor for diisocyanates?

• Further, it may also be appropriate to monitor 

the community and the environment. Some 

additional monitoring may include:

– Stack emissions testing

– Airborne release during and after spills (e.g., 

transportation incidents)
21

Exposure Evaluation

• The potential for exposure can depend on:

– Physical form and properties of the material

– Handling procedures

– Ventilation and type of environment

(e.g., confined space)

– Personal protective equipment

– Conditions of temperature and pressure

– Contact with other materials
22

Exposure Evaluation • Routes of exposure – Inhalation – Dermal – Eye – Ingestion • Nature of exposure – Vapor (gas) – Aerosol (mist)
23

Types of Monitoring

• Industrial Hygiene

– Personal

• Time-weighted average (TWA), long-term

• Short term exposure limit (STEL)

• Ceiling limit (C)

– Area

• Point source

• Leaks, spills and accidents

• Other

– Emissions (Stack) Sampling*

– Fugitive emissions*

*Not discussed in this presentation.
24

Types of Monitoring

Exposure Limits*

 MDI TDI

Ave Concentration (ppb)

Long Term (TWA) 5 5 

 Short Term (STEL) 20 

 Max Concentration (ppb)

 Ceiling 20 20

* As determined by OSHA, ACGIH
25

Measurements of Airborne MDI 

Concentration in the U.S. Workplace

This article summarizes data collected in 1984 through 1999. 

• 606 surveys were conducted for 251 companies at 317 facilities

– 3583 personal (breathing zone) samples and 4551 area samples

• Extremely low airborne MDI concentrations were measured 

• 74.6% of personal samples were non-detectable

• Modifications of OSHA Method 47 

• The LOQs ranged from 0.1–0.5 μg/sample 

Source: Booth, K. , Cummings, B. , Karoly, W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. 

W. , et al. (2009). Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in 

the U.S. workplace. Journal of Occupational and Environmental Hygiene, 6(4), 228-238.
26

Air Sampling Data

Source: Booth, K. , Cummings, B. , Karoly, W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). 

Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational 

and Environmental Hygiene, 6(4), 228-238.
27

Air Sampling Data

Source: Booth, K. , Cummings, B. , Karoly, W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). 

Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational 

and Environmental Hygiene, 6(4), 228-238.
28

Discussion

Based on MDI concentrations measured:

• very low vapor pressure

• whether the material is heated or sprayed

• how the diisocyanate is reacted

• whether manufacturing processes are open or closed 

systems

• whether impinger or filter paper sampling methods are 

used

Source: Booth, K. , Cummings, B. , Karoly, W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). 

Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational 

and Environmental Hygiene, 6(4), 228-238.
29

Conclusions

• Majority of personal samples show MDI concentrations 

ranging from below the LOQ to < TLV, however there 

can be higher concentrations. They include the following:

• Where MDI mixtures are spray applied or in situations 

where MDI is heated concentrations may be higher.

• When MDI is sprayed or used at elevated temperatures, 

consider additional control measures. 

Source: Booth, K. , Cummings, B. , Karoly, W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). 

Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational 

and Environmental Hygiene, 6(4), 228-238.
30

Industrial Hygiene Sampling Methods

• Air Sampling Techniques Most Commonly 

Used for Diisocyanates include:

– Direct Methods

• Paper tape

• Colorimetric (e.g., passive/active badge)

– Indirect Methods

• Chemically-treated filters

• Impinger solutions
31

Direct Sampling Methods Paper Tape 

Technology

• Summary

– Typically, the type of sampling method used to 

collect “real time” measurements of airborne 

isocyanates may use chemically treated paper tape. 

This technology is based on a comparison of light 

reflectance to the color/stain on the tape, which 

could be subject to interference.
32

Direct Sampling Methods Colorimetric 

Technology

• Summary

– Things to consider when using badge technology:

• Can be a valuable tool for the industrial hygienist:

– Worker acceptance is high

– Badge programs can operate efficiently with the oversight of 

an IH/Safety Professional

– screening tool

– visually evident characteristic color change
33

Indirect Sampling Methods

• Benefits:

– Provides a representative sampling of the environment

– Enables efficient collection and accurate reporting

– Lower LOQ and greater sensitivity than direct reading 

instrument

– Analysis available for:

• Monomers and oligomers 

• Considerations:

– Will need air sampling equipment (i.e., pump, calibrator, etc.) 

and training as to the use of this equipment

– Sample media (filter/impinger solution) requires 

preparation/handling prior to and after sampling
34

Indirect Sampling Methods

• Non-Spray applications

– When monomeric isocyanates are involved (i.e., MDI and TDI) 

consider glass fiber filters coated with a reagent (i.e., PP or 

MP).

• When sampling for MDI, desorb filters in the field.

– An impinger also can be used with a solution containing PP or 

MP (depending upon preference).

• Spray applications

– Where reactive aerosols (PMDI or polyisocyanates) are 

generated, consider impingers (containing a PP or MP solution).

• If aerosols are less than 3μm, consider backing-up the impinger

with a filter.
35

Exposure Monitoring

Sampler Types: 

– Coated Filter

– Impinger

Impinger + filter
36

Conclusion

• Consider periodic monitoring of airborne 

diisocyanates in the workplace. 

• Various instruments are available to assist in 

the assessment of the workplace.

• CPI is another resource; technical bulletins are 

available on the website for “easy access” at 

www.polyurethane.org.
APPENDIX 
Industrial Hygiene 

Exposure Control
39

Isocyanate Decontamination-Skin

• Animal testing concluded

– Polypropylene glycol, corn oil and polyglycol-based 

cleaner were generally more effective than soap and 

water

– Cleaning soon after exposure was important 

– Cleaning did not completely remove skin 

contamination

– Engineering controls, good work practices and PPE 

should be first defense against skin contamination
40

Respiratory Protection- APR

• To meet the OSHA criteria for APR use, 

respirators have a NIOSH certified End of 

Service Life Indicator (ESLI) or employers 

must follow a cartridge change schedule.

• APR cartridge change schedules are 

typically based on objective information 

or data. 
41

Respiratory Protection- APR

• OSHA Respirator 

Rule:

– User cannot rely on 

odor as a signal to 

change respirator 

cartridge for any 

chemical.
42

Respiratory Protection- APR

• Objective Information or Data for 

Cartridge Change Schedules

– Respirator manufacturers (e.g., see product 

pamphlet or website) 

– OSHA Technical Links „Isocyanates‟ website (Spence 

et al.; no breakthrough for OV/P100 after 24 hrs at 

500 ppb MDI aerosol)

– Technical Journals (Dharmarajan et al.[Am. Ind.Hyg. 

Assoc. J. (47):393-398 (1986)]; no breakthrough 

after 40 hrs at 2000 ppb TDI
43

Respiratory Protection- SARs

• Sources of breathing air include:

– Self contained breathing apparatus (SCBA)

– Air-lines

• Per OSHA, supply air should be equal to 

atmospheric air:

– 19.5 % to 23.5% oxygen

– Maximum 1000 ppm CO2

– Maximum 10 ppm CO
44

Respiratory Protection Written 

Respirator Program

• Voluntarily or company policy required by 

OSHA if employees wear respirators -

Applies to all respirators.
Industrial Hygiene 

Monitoring for 

Diisocyanates
46

Discussion

• OSB and many of the Binder applications involve spraying. 

Some CASE and Rigid Foam applications may also be spray 

applied. 

• During the manufacturing of OSB, engineered lumber, MDF, 

particleboard, etc., the PMDI on/in the substrate can be viable 

for hours, since there are no catalysts or polyol components to 

accelerate the reaction. The curing of PMDI on/in the various 

substrates takes place in the press under high temperature 

and pressure.

• On the other hand, spray applications in CASE, Rigid Foam, and 

some Binders usually involve a two-component system where the 

PMDI/MDI and catalyst containing polyols are combined via 

separate pressurized hoses into a mix head in the desired ratio. 

Once the two components are sprayed onto a surface, the 

reaction is completed within a minute or less. Some 

applications are made with rollers or brushes.

Source: Booth, K. , Cummings, B. , Karoly, W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). 

Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational 

and Environmental Hygiene, 6(4), 228-238.
47

Binders/ OSB

• 97.5% of the personal and 88.2% of the area samples 

were below the TLV. End-use applications are in 

construction (mainly in OSB), machinery and foundry. 

• For OSB, 97.2% of the personal and 93.4% of the area 

samples were below the TLV. 

*ACGIH MDI TLV is 0.051 mg/m3

Source: Booth, K. , Cummings, B. , Karoly, W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). 

Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational 

and Environmental Hygiene, 6(4), 228-238.
48

CASE (Coatings, Adhesives, 

Sealants, and Elastomers)

• Of the 417 personal entries, 126 were spray 

applications, 124 were brush/roller coating 

applications, and 79 were pour applications. 

• Of the 26 sampling results that were above the TLV, 17 

were spray applications; of the 13 that were the PEL, 9 

were spray applications. Personnel conducting spray 

applications are normally equipped with additional 

PPE, including respiratory protection.

*ACGIH MDI TLV is 0.051 mg/m3

* OSHA MDI PEL is 0.2 mg/m3

Source: Booth, K. , Cummings, B. , Karoly, W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). 

Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational 

and Environmental Hygiene, 6(4), 228-238.
49

Rigid Foam

• Personal and area sampling results below the 

TLV were 96.3% and 84.6% respectively.

• Spray-applied rigid foams are used as 

insulation on roofs of commercial buildings 

and as wall insulation for residential homes. 

• Many pour-in-place applications are used as 

insulation. 

Source: Booth, K. , Cummings, B. , Karoly, W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). 

Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational 

and Environmental Hygiene, 6(4), 228-238.
50

Rigid Foam

• The area (42/113) and personal (17/53) sample results 

for laminate boardstock that were above the TLV, 

37.2%, and 32.1% were non-spray applications. 

• In boardstock production, the chemical components are 

brought together in a mix head and open poured onto a 

continuous facing that is being transported by a 

conveyor. As the foam begins to rise, a second facing is 

brought into contact with the rising foam. The 

assembly moves through a heated conveyor press that 

controls the board thickness and accelerates the curing 

of the foam. The cured, sandwiched foam bonds to the 

facings and exits the press where it is cut to length, 

stacked, and made ready for shipment. 

Source: Booth, K. , Cummings, B. , Karoly, W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). 

Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational 

and Environmental Hygiene, 6(4), 228-238.
51

Flexible Foam

• Personal (99.1%) and area (95.5%) sampling results 

were below the TLV. End-use applications are in 

transportation, bedding, furniture, packaging, textiles, 

and others. 

• Subcategories under this product type include mainly 

foam-in-place or pour-in-place applications. 

Source: Booth, K. , Cummings, B. , Karoly, W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). 

Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational 

and Environmental Hygiene, 6(4), 228-238.
52

RIM (Reaction Injection Molding)

• Personal (99.5%) and area (97.0%) sampling results were below the 

TLV. 

• These processes refer to the injection of MDI/polyol mixture into a 

closed mold. The main applications (subcategories) are in the 

automotive and associated transportation, machinery, and foundry 

industries. 

• End products include automobile hoods, bumpers, body panels, 

chassis parts, spare wheel covers, tractor roofs, tractor seats, and 

others. 

Source: Booth, K. , Cummings, B. , Karoly, W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). 

Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational 

and Environmental Hygiene, 6(4), 228-238.
53

Other Foam

• Personal (97.3%) and area (93.9%) sampling results 

were below the TLV. 

• Subcategories include filling sealant cans and mostly 

carpet backing (rebond)/pour-in-place applications. 

Source: Booth, K. , Cummings, B. , Karoly, W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). 

Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational 

and Environmental Hygiene, 6(4), 228-238.
54

Other

• Personal (98.1%) and area (92.7%) sampling results 

were below the TLV. 

• Subcategories under this product type include extrusion 

(TPU), injection molding, bulk unloading from 

railcars/trucks, R&D lab testing, packaging, tote 

charging, and others. 

Source: Booth, K. , Cummings, B. , Karoly, W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). 

Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational 

and Environmental Hygiene, 6(4), 228-238.
55

Sampling

When monitoring for airborne MDI/PMDI, the analytical results can vary 

depending on the sampling method used.

• Use of impingers is suggested when air sampling for twocomponent, spray-applied systems that are fast reacting. The 

captured airborne particulates dissolve in the impinger, thereby 

facilitating the reaction between diisocyanates and the derivatizing

agent in the liquid medium.

• If a filter paper method is used, the airborne MDI/polyol

particulates impact on the filter media and the unreacted 

diisocyanate groups, which react rapidly with the polyol, may be 

physically hindered from reacting with the derivatizing agent on the 

filter. Consequently, the viable MDI in the sample could be 

underestimated.

• Therefore, consider field desorption of the filters to prevent the 

underestimation of MDI in the samples collected.

Source: Booth, K. , Cummings, B. , Karoly, W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). 

Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational 

and Environmental Hygiene, 6(4), 228-238.
56

Indirect Sampling Methods

• Most frequently used methods: 

– OSHA 42 (37mm PP-coated filter) -TDI

– OSHA 47 (37mm PP-coated filter) – MDI*

– NIOSH 5521 (Impinger with MP in toluene) – TDI/MDI

• Less frequently used methods: 

– NIOSH 5525 (MAP)

• Total NCOs (complex analysis) for monomer and oligomer species

– ISO-CHEK® (2-stage (untreated/MAMA) filter)

PP = 1-(2-pyridyl)piperazine

MP = 1-(2-methoxyphenyl)piperazine

MAP = 1-(9-anthracenylmethyl) piperazine

MAMA = 9-(N-methylaminomethyl)anthracene

Note: Airborne MDI is best collected using a 13mm filter which 

then is field desorbed