Spray Polyurethane Processes 

Daniel Almaguer, M.S.

Kathleen Ernst

Disclaimer: The findings and conclusions in this presentation are those 

of the author(s) and do not necessarily represent the views of the 

National Institute for Occupational Safety and Health (NIOSH). 

Mention of company names or products does not constitute endorsement 

by the Centers for Disease Control and Prevention (CDC) or NIOSH.
Who is NIOSH? 

 Created under the OSHAct of 1970

 Mission -To ensure safety and health at 

work for all people through research and 

prevention.

 Responsible for conducting occupational safety 

and health research.

 Education and Training.

 To provide leadership in research to prevent 

work-related illness, injury, disability, and 

death.
DART - EPHB

Division of Applied Research & Technology (DART)

Engineering & Physical Hazards Branch (EPHB)

 Conduct research on engineering controls (e.g. 

ventilation) to reduce exposures to hazardous 

agents.

 Engineers, Industrial Hygienists

 Identify, evaluate, design and disseminate 

information on engineering controls.
Spray Polyurethanes Usage 

 Products 

 Flexible foams

 Rigid foams

 Coatings

 Adhesives

 Industries

 Construction 

 Tanks and Pipes

 Bedding

 Adhesives

 Sealants

 Elastomers

 Binders

 Bedding

 Furniture

 Appliance

 Electronics

 Wheels and tires

 Packaging

 Textiles and Fibers
Polyurethanes = Isocyanates

 Isocyanates - highly reactive compounds 

containing the isocyanate group (-NCO)

 Isocyanates react readily with alcohol (- OH 

or hydroxyl) groups to produce polyurethane 

polymers

 Isocyanates are one of the raw materials from 

which polyurethane materials are made.
What is the Concern/Problem?

 Isocyanates are the leading attributable chemical 

cause of occupational asthma in the United States 

and many other industrialized countries

 Workers with asthmatic symptoms from 

isocyanate exposure often continue to have 

symptoms even after exposures have ended.

 Affected workers often have to leave their jobs to 

prevent further progression of respiratory 

symptoms.
MDI Health Effects

 Health effects result from inhalation and 

skin exposures. 

 Irritation and Lung Injury

 Respiratory Sensitization 

 Dermal Sensitization

 Acute exposure for some sensitized 

individuals may prove fatal (Feb. 2003).
Spray Polyurethane Foam 

Insulation (SPF)

 NIOSH has not conducted a study of SPF 

insulation process.

 NIOSH has conducted a comprehensive 

study of the TBL process.

 NIOSH has conducted a review of industry 

information on the SPF insulation process.

 Presentation of what we know about the two 

processes.
NIOSH Truck Bed-Liner (TBL) 

Study

 Identify shops with help of major 

companies.

 Assessed MDI exposures in TBL shops.

 PBZ and area sampling for MDI.

 Airflow measurements and evaluation of LEV.

 Evaluated spray booths and LEV systems to 

identify the best controls. 

 Recommended control strategies including 

engineering control design.
NIOSH TBL Study (cont.)

 Designed improved LEV system for sprayon bed-liner shops. CPI has also designed 

improved LEV.

 Compare isocyanate sampling methods: 

filter cassette vs. impinger/cassette.

 Disseminate information.

 TBL Alert

 TBL PPE Poster
MDI used in both TBL and SPF

 Methylenebis(phenyl isocyanate) [MDI] is used 

in both the TBL and SPF insulation processes.

 Studies show MDI in these two processes 

exceed the OELs.

 Heated product will result in increased airborne 

MDI concentrations.
TBL and SPF Insulation Processes 

Two Part Chemical Application

 Part A – Isocyanate 

 MDI

 pMDI

 Part B – Polyol Resin

 Amine catalyst

 SPF has a blowing agent

Applied with hand-held spray 

gun using pressurized system
Isocyanate Mixing and Curing

Component A

(Isocyanate)

Mix Polyurethane

Cure time?

Component B

(Resin)

Mix

TBL - Isocyanate component is 

almost always added in excess

to the mix to ensure a complete 

reaction. SPF?
Dermal Hazards before spraying

(Applies to both TBL and SPF)

 Absorption of isocyanates through skin 

 Can lead to sensitization

 Contamination and cross contamination of work surfaces can 

occur. Employees are exposed to the raw isocyanates handling 

opened containers and setting up equipment.
Hazards During Spraying

(TBL and SPF Spray Gun User)

 Inhalation and skin 

absorption

 MDI droplets in spray 

aerosol

 Increased MDI vapor 

from exothermic reaction

SPF process has additional 

workers in the area 

during spraying
TBL Real Time Aerosol Spray

Highly Variable Concentrations 

3

4

5

6

Relative Conc (mg/m3)

0

1

2

13:30:1313:31:0413:31:5513:32:4613:33:3713:34:2813:35:1913:36:1013:37:0113:37:5213:38:4313:39:3413:40:2513:41:1613:42:0713:42:5813:43:4913:44:4013:45:3113:46:2213:47:1313:48:0413:48:5513:49:4613:50:3713:51:2813:52:1913:53:1013:54:0113:54:5213:55:4313:56:3413:57:2513:58:1613:59:0713:59:5814:00:4914:01:4014:02:3114:03:2214:04:1314:05:0414:05:55

Time (h:m:s)

Relative Conc (mg/m3)

Unknown in SPF process – hazdust particle counter used 

to collect realtime data, not specific for MDI
Sampling Pump/Media 

for MDI Aerosols

NIOSH TBL Study compared impinger sampling 

method with filter method. Results indicated 

impingers captured levels of MDI 2-5 times higher

than filters
NIOSH TBL Study Results vs.

Canadian SPF Insulation Results

 TBL samples collected at six shops.

 Canadians SPF – five sites

 MDI monomer samples ranged up to 5.4 mg/m3

 Canadian SPF – 2.1 mg/m3  Canadian SPF – 2.1 mg/m3

 NIOSH REL = 0.2 mg/m3; 15-min. ceiling

= 0. 02 mg/m3; 8-10 hour TWA 

 OSHA PEL = 0.2 mg/m3; 10-min. ceiling
Other SPF Chemicals of 

concern

 Amine catalysts – considered 

proprietary in many cases 

 Blowing agent 
Spray Booth Results

 Samples exceeded NIOSH REL

 by 3 to 27 times the REL

 Canadian study - SPF exceed REL by 10.5x

 Always wear PPE, full-face respirator, and 

use exhaust ventilation when spraying.
Preparation Area Results

 Samples collected outside spray area/enclosure

 To assess ventilation and integrity of enclosure

 Below NIOSH REL

 But, some samples showed detectable 

concentrations

 Results document MDI is escaping enclosures

 Basis for Recommending enclosing spray area 

– Isolate the SPF spray area
Exhaust Results

 Detectable MDI concentrations were found at 

some exhaust locations.

 Sample location and wind direction possibly 

affected results, giving “non-detect” reading.

 Exhaust to unoccupied area.

 Prevent access to exhaust area.

 Does exhaust need to be filtered? 

discussion/research needed
Post Spray Results

 Detectable MDI concentrations in booth

 All below NIOSH REL

 15-30 minutes TWA samples: concentrations 

higher at the beginning of the sample period

 Assessment of SPF needed to determine when it 

is safe to re-enter and/or re-occupy area.

 Do not re-enter booth without PPE. Minimum 

needed is full-face APR with HEPA filters and 

chemical protective clothing to protect skin.
TBL Recommendations for 

Worker Protection
NIOSH TBL Alert - 2006

Contains Recommendations for:

 Workers

 Employers

 Future Research

 Engineering controls

 Exposure monitoring

 Respiratory protection

 Medical monitoring

 Surveillance

 Decontamination 
GOT EVERYTHING COVERED?

Keep yourself working safe by reading these helpful tips each day

before spraying...........

 To protect my lungs, wear a full-face supplied-air 

respirator 

 To help me see and to keep mask clean, use a peel-off 

shield 

 To protect my skin, wear a full-bodied suit and 

after spraying..............

 Remember to wash my hands and face before eating and drinking 

 If I experience symptoms, such as shortness of breath or skin irritation, 

tell my supervisor and my doctor 

 To protect my skin, wear a full-bodied suit and 

chemical-resistant gloves 

 To keep the ventilation system operating at its best, 

make sure the filters are clean 
GOT EVERYTHING COVERED?

For more information on protecting yourself from the hazards 

of isocyanate exposure during spray-on truck bedliner 

application:

Contact the National Institute for Occupational Safety and 

Health at 

1-800-CDC-INFO (1-800-232-4636)

Also visit the NIOSH Isocyanate Topic Page at 

http://www.cdc.gov/niosh/topics/isocyanates/

DEPARTMENT OF HEALTH AND HUMAN 

SERVICES

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

DHHS (NIOSH) Publication No. 2008-109
TBL Recommendations

 Use Personal Protective Equipment (PPE) and 

respirator- Applies to SPF

 Enclose the spray booth – SPF isolate area to 

ensure others are not exposed

 Provide adequate exhaust ventilation to remove 

MDI – SPF explore ways to safely exhaust

 Limit access to spray area - Applies to SPF

 Exhaust through roof and prevent access-SPF 

prevent access to exhaust area

 Do not re-enter booth without PPE- SPF spray area
Protective Clothing and Equipment

(TBL and SPF)

 Full-face supplied air 

respirator.* NIOSH-approved 

supplied-air respirator with a full 

facepiece operated in a pressuredemand or other positive-pressure 

mode

 Supply air must come from 

uncontaminated area

 Chemical protective clothing to 

protect skin

 Hooded respirators acceptable 

if tested and certified to meet 

higher APF of 1000
Eye and Face Protection

 Vapors of diisocyanates are corrosive and 

severely damaging to the eyes. Contact may 

cause permanent eye damage.
Hand and Skin Protection

 Protective equipment such as gloves and 

faceshields must be worn to protect skin. 

 Double glove

 Use tools, such as spatulas, to avoid skin 

contact.

 Treat outside of containers as contaminated.
Hand and Skin Protection (cont.)

 Protective clothing (coveralls, gloves, booties) should 

be made of a material resistant to isocyanates.

 Gloves:

 Butyl rubber gives the best protection.

 Nitrile rubber, chlorinated polyethylene, and polyvinyl 

alcohol provide adequate protection for short term 

exposure.

 Even the most resistant materials may be penetrated 

quickly and should be replaced often.
Work Practice Controls

 Contaminated clothing and equipment should be 

decontaminated before it is reused.

 For example: a solution of 90% water, 3-8% ammonia and 2% 

liquid detergent.

 Do not take contaminated work clothing home. 

 Eyewash fountains should be provided in the immediate 

work area for emergency use.

 Do not eat, smoke or drink where isocyanates are 

handled, processed or stored. 

 Wash hands carefully before eating, drinking, smoking 

or going to the washroom.
Medical Surveillance

 A physical examination, including an occupational 

and medical history, at the beginning of employment.

 Lung function tests and history of asthma, bronchitis, 

emphysema, allergies, or other breathing problems.

 Yearly follow-up examinations, including lung 

function tests at the beginning and end of a single 

shift or work week.

 See a pulmonary specialist if symptoms from 

isocyanate exposure develop. 
Enclosure Design*

 Isolate the spray process – Applies to SPF.

 Build a spray enclosure to contain airborne MDI 

within the enclosure. 

 WARNING: This will result in increased 

concentrations within the enclosure, so the enclosure 

will need exhaust ventilation

 Limit physical dimensions of the enclosure to the 

smallest floor area and room volume compatible 

with the spray operation to maximize the 

efficiency of the ventilation system.

* CPI - Website has information on TBL 

enclosures
Ventilation of Spray Enclosure

 Provide exhaust ventilation to capture vapor and 

particulate MDI near the point of generation.

 SPF explore use of air movers to exhaust, every space would be 

different;

 Clean up of residual dust from trimming is an issue; 

 Ensure exhaust area is clearly labeled; 

 Prevent access to exhaust area.

 Provide make-up air for the enclosure.

 Balance supply air and exhaust air to ensure that the spray 

enclosure is under negative pressure.

 For SPF process this needs to be studied or assessed.

 Assessment of blowing agent and amine catalyst needed
Ventilation of Spray Enclosure 

(cont.)

 The exhaust rate should be based on the physical 

dimensions of the spray enclosure and provide a 

minimum of 6 air changes per hour.

 Make-up air supply up air supply and exhaust should and exhaust should be located be located 

to generate a directed air flow that maximizes 

ventilation efficiency and contaminant control. 

 For the SPF process this needs to be studied
Ventilation of Spray Enclosure 

(cont.)

 Discharge the exhaust air through the roof.

 Locate exhaust stack away from air intakes, 

garage doors, or other openings where the exhaust 

could re-enter the shop or other occupied areas.

 Ensure exhaust is discharged above the roof 

recirculation region (See Industrial Ventilation: A 

Manual of Recommended Practice [ACGIH 2004]

to determine the recirculation region). 

 Control access to exhaust discharge areas by 

physical barrier and warning signs. 

 Needs to be assessed for the SPF process.
Implementation GAP

Hierarchy of controls

 Elimination

 Substitution - replace high hazard with low 

hazard

 Engineering – ventilation, enclosure

 Protective Clothing and Equipment -

respirators, ear plugs, gloves

 Administrative - training, procedures, policy

 Gap between what we know and what the 

worker does.
Initial Assessment of SPF

 The industry has a wealth of Information on 

spray polyurethane products.

 Indications that the information is not 

consistently reaching the worker.

 We need to work collaboratively to protect 

the health of the SPF workforce.

 Develop a series of messages for the worker

 Ensure that correct information gets to the 

workers
Sources of OS&H Information

 NIOSH Website: www.cdc.gov/NIOSH

 NIOSH 800 Number -- 1-800-CDC-INFO

 OSHA Website: www.osha.gov

 Manufacturers or Product Distributors

 Center for the Polyurethanes Industry 

website – www.polyurethane.org – many 

publications on MDI and other isocyanates.
Contact Information

Daniel Almaguer, MS

NIOSH

Division of Applied Research and Technology

Engineering and Physical Hazards Branch

4676 Columbia Parkway, Mailstop R-5

Cincinnati, Ohio 45226

Phone: (513) 841-4221

FAX: (513) 841-4506