1

A Proposed Methodology for Establishing a Safe Work Zone 

around an SPF Application to Exterior Walls of a Commercial 

Structure

SCOTT ECOFF

Bayer Material Science

 100 Bayer Road

 Pittsburgh, PA 15205

 

 

JIM LAMBACH

Bayer Material Science 

100 Bayer Road

 Pittsburgh, PA 15205

 

 

ABSTRACT

 Bayer MaterialScienceTM (BMS) evaluated airborne concentrations of spray polyurethane foam (SPF) chemicals during 

application of continuous insulation to exterior walls of commercial structures. Application of medium-density closed-cell 

SPF involves the use of various chemicals including methylene diphenyl diisocyanate (MDI), amine catalysts, and a 

hydrofluorocarbon. Airborne concentrations of these chemicals in the spray area require the applicator and helpers to wear 

respiratory protection and protective clothing. The potential for SPF chemical exposure to other construction trade workers 

has not been well characterized. The Center for the Polyurethanes Industry (CPI) in its “Health and Safety Product 

Stewardship Workbook for High-Pressure Application of Spray Polyurethane Foam” listed considerations for site 

preparation that include establishing a work zone around the work area to minimize exposure to adjacent workers during 

SPF application. It indicates that the distance between the SPF application work area and adjacent workers is typically 25 

feet, but adds that the distance depends on several factors. The purpose of this study was to assess airborne concentrations 

of SPF chemicals at specific distances from the application area and develop a methodology that could be used by the 

industry to help protect non-SPF workers from spray foam chemicals at commercial construction work sites.

 Based on our research, it appears that establishing the boundary for the “safe work zone” at a minimum distance of 50 feet 

is appropriate for exterior SPF work in the absence of control methods such as isolation and exhaust ventilation. Outside 

SPF application work is highly influenced by wind speed and at 25 feet downwind it appears likely that workers from other 

trades could periodically work in areas with airborne MDI monomer concentrations between 10% and 47% of the 

occupational exposure limit (OEL). This paper suggests using a guideline of less than (<) 10% of the OEL for establishing 

perimeter protection around the SPF applicator. Since there are many variables that can affect spray drift and movement of 

airborne chemical vapors around an SPF exterior wall application, a proposed methodology consisting of three steps is

outlined to help protect non-SPF workers prior to, during, and post application. 

BACKGROUND

 This study focused only on application of high pressure SPF systems manufactured by Bayer MaterialScience (BMS). 

The BMS SPF formulations evaluated in this study were those used to produce Bayseal® and EcoBayTM medium density 

closed cell foams. Four construction work sites were visited while SPF was applied to exterior walls, each in a different 

geographical region of the United States.

 

 The SPF contractors that volunteered to participate in this study were requested to obtain approval from the General 

Contractor (GC) before each site visit. BMS did not provide any guidance prior to the site visit on how or where to set-up a 

safe work zone around the SPF application area. This approach was used so BMS could observe current practices on how

safe work zones are established at a typical commercial construction project. Interviews with SPF supervisors and 

observations made during each site evaluation helped to assess current practices used to establish a safe work zone.
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 The typical SPF system is comprised of an “A” side and a “B” side which, when combined, form polyurethane foam within 

a few seconds. The A-side, polymeric methylene diphenyl diisocyanate (pMDI), contains approximately equal amounts of 

monomeric MDI (predominantly 4,4’-MDI, a chemically bonded two ring structure) and higher molecular weight oligomers 

of MDI (three-ring bonded structures and larger). The B-side is a blend of chemicals, typically containing polyols, flame 

retardants, catalysts, blowing agents, surfactants, and other additives. 

 There are several published studies documenting airborne concentrations of some chemical components contained within 

the A and B-side of a typical SPF system. The existing work shows clearly that MDI exposures for both the spray foam 

applicator and helper can exceed both task and work shift occupational exposure limits1

. This is true for both exterior and 

interior applications of SPF insulation, with outdoor projects generally resulting in airborne MDI levels less than 50% of 

those measured during interior SPF applications. Airborne concentration levels of some of the B-side components are not as 

well documented, but it would seem reasonable that one could detect these SPF constituents. It should be noted that some 

B-side chemical components, specifically many of the amine catalysts, do not have published exposure limits making it hard 

to interpret the air sampling data for determining a safe level of exposure. Because of the nature of the chemical hazards 

associated with SPF application, it is important for SPF installation contractors to not only be well aware of the protective 

measures needed for their own workers but also to establish worksite guidelines for protection of non-SPF trade workers at 

the site. The respiratory protection and protective clothing needed to prevent inhalation of and skin/eye contact with SPF 

chemicals requires proper selection and specific training to ensure PPE is used properly. Most non-SPF workers would not 

have the PPE or training needed to adequately protect them if assigned to a project that required working near an SPF 

application. The Center for the Polyurethanes Industry (CPI) (www.spraypolyurethane.org) and the Spray Polyurethane 

Foam Alliance (SPFA) (www.sprayfoam.org) are good resources for Health & Safety information as well as guidance on 

selection of personal protective equipment for SPF applicators and helpers.

Current Guidance and Study Observations for Protection of non-SPF Workers

 

 It is the opinion of the authors that most SPF contractors are generally aware of the following guidance from the CPI

webpage titled “Health and Safety -Site Preparation” that addresses protection for non-SPF workers.

“If local exhaust ventilation and containment methods are not used, establish a safe work zone around the work area to 

protect adjacent workers. The distance between the work area and adjacent workers is typically 25 feet, but depends 

on several factors, including but not limited to volume of SPF applied, the area covered, and air movement. Signage 

may be used to communicate access restrictions. Consider limiting access to persons wearing proper personal 

protective equipment or trying to schedule other trade workers at times when SPF application is not underway.”

 

 The CPI “Health and Safety Product Stewardship Workbook for High-Pressure Application of Spray Polyurethane Foam” 

provides similar information. Another publication from the Canadian Urethane Foam Contractors Association also provides 

guidance to SPF contractors for protecting workers from other trades. It suggests that, since outside spray application is 

highly influenced by wind speed, an “exclusion zone” be established at 6 meters (20 feet) on either side of the applicator in

still air conditions, or 3 meters (10 feet) upwind and 8 meters (25 feet) downwind of the applicator.

2

 

 Engineering control techniques such as exhaust ventilation and isolation (e.g. plastic sheeting, tarps, wind screens) were 

not used at any of the work sites evaluated by BMS. The SPF contractors interviewed during this study agreed that it is 

necessary to establish protective measures to prevent exposure of non-SPF workers to the chemicals associated with 

application of high pressure spray foam insulation. However, implementing a standardized procedure to protect non-SPF 

workers is difficult. This is most likely due to how quickly SPF can be applied and the many variables that cause changing 

conditions at each construction project (e.g. project schedule, number of other contractors on site, height/size of the 

structure, proximity of other buildings/access roads to the work site, number of SPF applicators, type of work platforms

used by the SPF contractor to apply spray foam, environmental conditions such as wind, temperature, and humidity). 

STUDY METHODOLOGY

 There are many reference materials available from CPI/SPFA that explain the equipment used in applying polyurethane 

foam insulation. Therefore, the methodology described below will focus only on the SPF chemicals evaluated, how 

sampling locations were selected around the application area, and the air sampling and analytical techniques used to 

complete this study.

SPF Chemicals Evaluated
3

 The specific SPF chemical components selected for evaluation during installation of closed cell foam insulation used 

during this study included: 

• Polymeric MDI (the A-side material represents 50% by volume of the mixture to produce PU foam)

• Amine catalysts (three amines are included in each B-side SPF formulation but are not specifically identified for

proprietary reasons; they are identified in this report as Amine #1, #2, and #3)

• 1,1,1,3,3-Pentafluoropropane (blowing agent)

 Although there are other chemicals found in the B-side of the SPF formulation, this study focused only on the above 

chemicals. The primary reasons are listed below: 

• The chemical components evaluated are generally considered the most likely to be emitted during SPF application 

due to their composition within the formulation and physical characteristics (vapor pressure, boiling point, etc...)

• BMS industrial hygiene sampling and analytical methods exist for these chemicals (not publically available)

• Limitations associated with the number of pumps and types of sample media that can be practically used per 

sample location

Air Sampling and Analytical Techniques

General 

 Industrial hygiene air sampling pumps used during this investigation included SKC Airchek 52 and A.P. Buck Libra

models. The SKC Airchek sample pumps were used for collection of the amine and blowing agent samples. The Buck 

Libra sample pumps were used for collection of the MDI/pMDI samples. All air sampling pumps were calibrated before 

sample collection to the appropriate sampling rate, as specified in the Sampling and Analytical Method provided by the 

analytical laboratory, using a Bios DryCal® DC-Lite Primary Flow Meter. The sampling rate was measured after each 

sampling event, and the average of the pre- and post-value was used to calculate the total sample volume. To assess the 

airborne concentrations within the SPF Applicator breathing zone, the sample media was attached near the neck/shoulder 

area (outside the respirator). To assess airborne concentrations at specific locations around the SPF Applicator, tripods or 

step ladders were used to mount the sample media at breathing zone height (e.g. 4 to 6 feet above ground level). All 

samples were analyzed at the BMS Industrial Hygiene Laboratory, which is accredited by the American Industrial Hygiene 

Association (AIHA). 

 

Polymeric MDI (includes monomeric forms of MDI and oligomers of MDI referred to as pMDI)

 For the purpose of this paper, pMDI refers to three-ring bonded structures and larger. Air samples for monomeric MDI 

and pMDI were collected using glass impingers containing 15 milliliters of a solution of toluene and 1-(2-pyridyl) 

piperazine backed up by coated 13 millimeter (mm) glass fiber filters (SKC, 1.0 μm, type AE) mounted in two-piece 

Millipore Swinnex cassettes. Each filter is coated with 2 milligrams (mg) of 1-(2-pyridyl) piperazine and diethyl phthalate. 

Per the BMS sampling and analytical method, the sample flow rate was approximately 1.0 liter per minute (LPM). Soon 

after completion of the sampling period and post calibration, the filter was removed from the Swinnex holder and desorbed 

in 2 milliliters (mL) of acetonitrile/dimethyl sulfoxide (90:10 v/v) solution. The impinger solution was transferred from the 

midget impingers to amber glass bottles where they were subsequently packaged for shipment to the laboratory. When 

airborne MDI/pMDI is drawn through the impinger solution and the filter, it is converted to a stable urea derivative, which 

is quantitatively analyzed by High Performance Liquid Chromatograph (HPLC) with fluorescence detection. BMS 

Sampling and Analytical Methods 1.20.1 (impinger solution) and 1.7.7 (filter desorption fluid) were used for evaluation of 

MDI/pMDI.

Amine Catalysts 

 Sampling for amine catalysts was accomplished using XAD-2 sorbent tubes (SKC Inc. 226-30-06; 8 mm diameter x 110 

mm). Sampling was conducted at a rate of approximately 0.5 LPM. Each sample was quantitatively analyzed by Gas 

Chromatograph/Mass Spectrometer (Nitrogen Phosphorus Detector) using BMS Industrial Hygiene Laboratory Method 

2.10.3. 

Blowing Agent 
4

 Sampling for the blowing agent (1,1,1,3,3-pentafluoropropane or HFC-245fa) was accomplished using a large charcoal 

tube (SKC Inc. 226-09, 8 mm x 110 mm). Sampling was conducted at a rate of approximately 0.05 LPM. Each sample was 

quantitatively analyzed by Gas Chromatograph/Flame Ionization Detector using BMS Industrial Hygiene Laboratory 

Method 3.53.0.

 

Occupational Exposure Limits (OEL)

MDI/pMDI 

 The American Conference of Governmental Industrial Hygienists (ACGIH) has adopted a Threshold Limit Value – Time 

Weighted Average (TLV-TWA) for 4,4’-methylene bisphenyl isocyanate (MDI) of 51 micrograms per cubic meter (ug/m3

) 

or 5 parts per billion (ppb). This is an airborne concentration for a normal 8-hour workday and a 40-hour workweek and 

represents conditions under which nearly all workers can be exposed without adverse health effect. In addition, the federal 

Occupational Safety and Health Administration (OSHA) has established a Permissible Exposure Limit (PEL) for 4,4’-MDI 

of 200 ug/m3 or 20 ppb as a Ceiling (C) limit. The Ceiling limit is a concentration that should not be exceeded without the 

use of proper respiratory protection during any part of the work day. 

 At present, neither an ACGIH TLV nor a federal OSHA PEL has been established for 2,4’-MDI or polymeric MDI 

(pMDI). However, Bayer MaterialScience recommends that the exposure limit for 4,4’-MDI (51 ug/m3

) be used for the 

2,4’-MDI isomer as well as for pMDI. 

Amine Catalysts 

 At present, none of the amine catalysts evaluated during this study have published occupational exposure limits (OELs).

1,1,1,3,3-Pentafluoropropane (blowing agent HFC-245fa) 

 The American Industrial Hygiene Association (AIHA) has established a Workplace Environmental Exposure Level 

(WEEL) for 1,1,1,3,3-pentafluoropropane of 300 parts per million (ppm) as an 8-hour TWA concentration. The AIHA 

Guideline Foundation WEEL provides guidance for protecting most workers from adverse health effects related to 

occupational chemical exposures. They are not intended for the general public and are normally averaged over an 8-hour 

workday and serve to protect against acute and chronic health effects. 

Sampling Locations

Personal 

 Personal air samples were collected on the SPF applicator for the purpose of determining the airborne concentrations of 

each SPF chemical evaluated in the immediate spray zone or application area. The personal samples were collected only 

during application of SPF insulation. The personal MDI air samples were typically collected for a sample period of one to 

two hours. The personal amine/blowing agent air samples were typically collected for a sample period of two to three 

hours. The sample time periods were based primarily on the ability to report to a specific minimum airborne concentration. 

Application of SPF insulation occurred for approximately four hours at each of the work sites visited.

Area 

 Because many SPF contractors are aware of the CPI guideline of establishing a distance of 25 feet between the SPF 

application work area and other non-SPF workers, area sample locations were established at a distance of 25 feet left, right, 

and behind the Applicator. Another area air sample location was selected at a distance of approximately 50 feet downwind 

of the Applicator. For each site visit, one additional area sample location was selected inside the building. The sample 

inside the building was located on the opposite side of the wall from where the SPF was being applied, at a distance of 

approximately 10 feet from the exterior wall. Window and doorway openings were covered with plastic at each site. Air 

sampling equipment was mounted on tripods or step ladders and moved as the job progressed.

RESULTS AND DISCUSSION

 All the air sample results are illustrated on three tables found at the end of this paper. Table 1 illustrates the airborne 

concentrations of MDI and pMDI (oligomers). Table 2 illustrates the airborne concentrations of the amine catalysts 
5

evaluated. Table 3 illustrates the airborne concentrations of 1,1,1,3,3-pentafluoropropane (blowing agent). The following 

paragraphs summarize the airborne concentrations found, and the applicable criteria levels used to compare results.

Personal Sample Results - SPF Applicator

 MDI/pMDI

 Airborne concentrations of MDI and pMDI were detected on all the SPF Applicator samples collected at each of the four 

work sites. As discussed previously, the individual sample periods on the Applicator generally ranged from one to two 

hours resulting in multiple long-term samples collected per work shift. The average airborne concentrations of monomeric 

MDI (2,4 and 4,4-MDI added together) in the Applicator breathing zone for each site visit were 31 micrograms per cubic 

meter (ug/m3

), 70, 85 and 195 ug/m3. This correlates to airborne MDI concentrations during SPF application ranging from 

61% to 382% of the recommended occupational exposure limit (ACGIH TLV = 51 ug/m3

). The values illustrated in Table 1

are the average airborne MDI concentrations found during the spray period and not the 8-hour work shift average. The 

airborne concentrations of pMDI were similar to the airborne concentrations for monomeric MDI. The average airborne 

concentrations of pMDI in the Applicator breathing zone for each site visit were 17, 79, 111, and 191 ug/m3

. 

 

 Amine Catalysts

 

 Airborne concentrations of amine catalysts were detected on only one SPF Applicator (at site visit #2). One of the amines 

in the SPF formulation (Amine #2) resulted in airborne concentrations of 37 and 41 parts per billion (ppb) on the Applicator

at this particular work site. Other than these two data points, all other amine airborne concentrations were non-detectable 

(ND) less than the analytical limit of quantitation (LOQ).٭ Table 2 illustrates the LOQ values for each sample. None of 

the amine catalysts evaluated have a published occupational exposure limit (OEL). 

 ٭Note: The limit of quantitation (LOQ) refers to a minimum concentration of a chemical that can be measured within the 

specified limits of precision and accuracy set by the laboratory analytical method (instrumentation). The LOQ is also 

dependent upon the sample duration and flow rate, which is used to calculate the volume of air sampled. When reporting 

non-detectable (ND), it means that the chemical is not present in a sufficient amount to be reliably quantified below this 

value.

 Blowing Agent

 Airborne concentrations of blowing agent were detected on two SPF Applicators (at site visit #3 and #4). The airborne 

concentrations of blowing agent where detected ranged from 3.8 parts per million (ppm) to 6.8 ppm. These values are less 

than 3% of the OEL. All other blowing agent air sample results as illustrated in Table 3 were less than the LOQ (all ND < 

10 ppm). The blowing agent has an OEL of 300 ppm (AIHA WEEL). 

Area Sample Results

MDI/pMDI

 The outline below summarizes the airborne concentrations of MDI/pMDI at 25 feet (left, behind, right), 50 feet downwind 

of the SPF Applicator, and inside the building. 

• 25 Feet: Detectable airborne concentrations of MDI monomer (2,4 and 4,4’-MDI) were found at three of the 

four work sites surveyed. MDI was detected on eleven of eighteen area air samples collected at 25 feet to the 

left, behind, or right of the SPF Applicator. The average airborne concentration of MDI monomer at the 

eleven sample locations where detected was 9.5 ug/m3 (approximately 18% of the TLV of 51 ug/m3

) and 

ranged from 1.0 to 23.9 ug/m3

. PMDI was detected on only four of eighteen area air samples collected at 25 

feet. 

• 50 Feet: Detectable airborne concentrations of MDI monomer were found at two of the three work sites 

surveyed at this distance. MDI was detected on three of the five area air samples collected at 50 feet 

downwind of the SPF Applicator. The three detectable airborne MDI results at 50 feet downwind were 1.0, 

2.4, and 3.9 ug/m3 (approximately 2% to 8% of the TLV). PMDI was not detected on any of the area air 

samples collected at 50 feet. 

• Inside Building: Detectable airborne concentrations of MDI monomer were found inside the building at one of 

the four work sites surveyed. The one work site where MDI monomer was detected resulted in airborne 

concentrations of 14.0 and 19.8 ug/m3 (27% to 39% of the TLV). Breaches (e.g. small holes and openings) in 
6

the plastic covering the windows were observed in close proximity to the sampling stations inside the building 

and most likely contributed to the detectable airborne MDI values. 

Amine Catalysts

 

 The outline below summarizes the airborne concentrations of amine catalysts at 25 feet (left, behind, right), 50 feet 

downwind of the SPF Applicator, and inside the building. 

• 25 Feet: All sixteen area air samples collected at 25 feet were ND less than the LOQ for all three amines 

contained within the SPF formulations. 

• 50 Feet: All six area air samples collected at 50 feet were ND less than the LOQ for all three amines 

contained within the SPF formulations.

• Inside Building: All seven area air samples collected inside the building during spray application were ND 

less than the LOQ for all three amines contained within the SPF formulations. 

 Blowing Agent

The outline below summarizes the airborne concentrations of blowing agent at 25 feet (left, behind, right), 50 feet 

downwind of the SPF Applicator, and inside the building. 

• 25 Feet: All fifteen area air samples collected at 25 feet were ND less than the LOQ for 1,1,1,3,3-

pentafluoropropane. The LOQ values for each sample were all < 1% of the OEL of 300 ppm.

• 50 Feet: All four area air samples collected at 50 feet were ND less than the LOQ for 1,1,1,3,3-

pentafluoropropane. The LOQ values for each sample were all < 1% of the OEL.

• Inside Building: All seven area air samples collected inside the building during spray application were ND 

less than the LOQ. The LOQ values for each sample were all < 1% of the OEL.

Criteria Used to Assess Acceptable Airborne Chemical Concentrations to non-SPF Workers

 Exposure assessment models exist to assign a risk factor to employees working with hazardous agents (e.g. chemical 

hazards, physical hazards such as noise, biological hazards, etc...). It is beyond the scope of this paper to provide a 

summary of the various models/techniques available for conducting occupational exposure assessments. It is important to 

note there are many factors to consider when assessing the hazards associated with an exposure such as application of SPF 

insulation. These factors include: the unique toxic characteristics of each chemical agent involved, potential changes in the 

toxic characteristics when they exist in mixtures, potential for some chemicals to be absorbed into the body upon skin 

contact, variations in duration of exposure to chemicals, type of PPE/work clothing worn, and environmental conditions. 

 For the purpose of this paper, the authors relied primarily upon air monitoring data in determining guidance for 

establishing a boundary (perimeter distance) sufficient to protect non-SPF workers from SPF chemical vapors and aerosols. 

The authors used recommended criteria published by the American Industrial Hygiene Association (AIHA) in a reference 

entitled: “A Strategy for Assessing and Managing Occupational Exposures.” Figure 1 below is specific to occupational 

exposures (work sites) and not to be used for establishing criteria for members of the general public (by-standers that are not 

assigned to work at the site). 

Figure 1

Criteria for Assessing Occupational Exposure to Chemicals3

Exposure Rating٭ Description Actual or Estimated Exposure

(% of OEL)

1 Highly Controlled < 10%

2 Well Controlled 10-50%

3 Controlled 50-100%

4 Poorly Controlled >100% ٭Ratings based on “A Strategy for Assessing and Managing Occupational Exposures”, 2006, 3rd edition. American

Industrial Hygiene Association, Fairfax, VA.

 Based on the criteria above, the “safe work zone” boundary for non-SPF workers at an SPF insulation project should be 

established so that chemical exposures are less than 10% of a published occupational exposure limit (i.e. OSHA PEL, AIHA 
7

TLV, AIHA WEEL, NIOSH REL) or a chemical manufacturer’s recommended limit. Material Safety Data Sheets (MSDS) 

are one reference for finding regulatory, professional association, organizational (i.e. NIOSH), or manufacturer OELs.

 The authors recognize that using the above criteria is a conservative approach to establishing a “safe work zone” for 

exterior SPF applications. Because there are several chemicals associated with this type of operation and the various factors 

discussed previously that can influence risk of exposure, it appears to be a prudent approach in the efforts to prevent 

exposure to non-SPF workers.

CONCLUSIONS & RECOMMENDATIONS

 It is common at construction projects for several other construction trades such as plumbers, carpenters, ironworkers, and 

electricians to be at the work site during SPF application. The OSHA Hazard Communication regulation (1910.1200 and 

1926.59) defines minimum requirements that must be established when chemicals are handled/used at multi-employer work 

sites. To briefly summarize the requirements, the OSHA Hazard Communication standard requires the contractor using a 

hazardous chemical that could result in exposure to other workers to provide labeling and MSDS information about those 

chemicals. There is no specific guidance on how to establish a “safe work zone” nor is there a clearly defined safe airborne 

concentration for a chemical where other workers would be considered “not” exposed. It would be difficult to provide 

specific guidance due to the many variables discussed earlier that affect risk of exposure to chemicals. So, it is not 

surprising that safety professionals involved with overseeing an SPF insulation project struggle with the concept of 

establishing a safe working distance for non-SPF workers. The following paragraphs provide a proposed methodology for 

protecting non-SPF workers during an exterior insulation construction project.

 Airborne concentrations of amine catalysts and blowing agent were below the analytical limit of quantitation at the 25 feet 

sample locations set up to the right, behind, and left of the Applicator. However, airborne MDI monomer concentrations 

above 10% of its OEL were found at these sample locations at three of the four work sites evaluated. Therefore, the 

findings of this study indicate that MDI is the primary airborne SPF chemical detected during exterior SPF application. 

BMS believes that establishing a boundary for the “safe work zone” at a minimum distance of 50 feet helps protect non-SPF 

workers in the absence of control methods such as isolation and exhaust ventilation at the SPF application area.

 Inhalation of SPF chemicals is not the only exposure route of concern. One must also consider the potential for direct 

skin/eye contact with SPF chemical aerosols (e.g. mist particles from spray drift). Other non-SPF workers would not 

typically be provided PPE to prevent skin contact from chemical hazards. Therefore, a comprehensive tiered approach is 

necessary when establishing guidelines to protect non-SPF construction trade workers from chemical hazards associated 

with an SPF insulation project.

 As a starting point for protecting non-SPF workers, the authors suggest that SPF contractors read and be knowledgeable 

with the CPI/SPFA guidance document entitled “Exterior Spray Polyurethane Foam Insulation Health & Safety Q&A.” The

tiered approach below includes many good work practices published in this document, as well as findings based upon

observations made during this field study.

 Proposed Methodology to Establish a Safe Work Zone and Protection of non-SPF Workers at Commercial 

Construction Work Sites

A. Step #1: Planning of SPF Work (prior to the date of application)

• Meet with the General Contractor, Construction Manager, and building owner representatives to discuss 

chemical hazards of SPF application work. Use health and safety information like that available from CPI 

and SPFA to inform them of potential SPF hazards and good work practices to establish to protect other 

workers. 

• Request that the General Contractor assist in properly scheduling SPF application work to avoid other trades 

from being on site while SPF is sprayed. 

• If other construction trades must be on site, establish protective measures to ensure non-SPF trade workers 

are not within 50 feet of the SPF application area in the absence of control methods such as isolation and 

ventilation. In some situations, a perimeter greater than 50 feet may be necessary due to natural air 

movement (wind speed), size of SPF area to be sprayed, and height of the structure.

• Inform supervisors of non-SPF trade workers of the chemical hazards associated with SPF application work

per OSHA Hazard Communication requirements.

• Develop an Overspray Mitigation Plan (see CPI/SPFA document referenced previously). 
8

• Plan to isolate and ventilate the spray application area when it appears difficult to control overspray or site 

conditions restrict the ability to establish a safe work zone of 50 feet.

B. Step #2: SPF Application (on the day of application)

• Check wind forecast for day (adjust overspray mitigation plan as necessary)

• Restrict access to the SPF application area.

• Establish a boundary (safe work zone) of at least 50 feet to the left, behind, and right of the SPF Applicator. 

Be sure to take into account factors that can affect spray drift and the entire area where SPF will be applied.

• Post warning signs and install physical barriers (e.g. snow fence, saw horses, warning tape, cones, etc...) to 

help keep non-SPF workers from entering the safe work zone.

• Ensure all window and doorway openings are covered. When other construction trade employers must work 

on the other side of the building enclosure, use durable building materials (e.g. wood) along with tarps or 

plastic sheeting to prevent SPF mist and vapors from entering the structure through window/doorway 

openings.

C. Step #3: Post Spray Application

• Non-SPF workers should not enter the spray area until the SPF contractor has removed all spray equipment 

and cleared the work zone. 

• Establish appropriate housekeeping procedures to clean up debris associated with SPF application work

before leaving the site. 

• Ensure all waste materials (SPF debris, empty drums, or any liquid A or B-side chemicals) are disposed of 

properly (e.g. contact the chemical manufacturer and federal, state, and local agencies to be aware of the 

regulations pertaining to this work). 

REFERENCES 

1. Spence, M., 2009. “The Current MDI Industrial Hygiene Data on Spray Foam” in Center for the Polyurethanes 

Industry (CPI) Conference, 2009.

2. Canadian Urethane Foam Contractors Association (CUFCA). 2005 Assessment of Isocyanate Exposure during 

Outdoor Spray Application of Polyurethane Foam for Cavity Wall Insulation. CUFCA Safety Bulletin, Winnipeg, 

Manitoba: Canadian Urethane Foam Contractors Association. 

3. Ignacio, J.S., Bullock, W.H. 2006. ISBN: 978-1-931504-69-0 “A Strategy for Assessing and Managing Occupational 

Exposures”, American Industrial Hygiene Association (AIHA). 

ACKNOWLEDGEMENTS

 This study was conducted by Bayer MaterialScience LLC, Spray Foam Roofing & Insulation Group, Product Safety & 

Regulatory Affairs Department, and the Industrial Hygiene & Environmental Analytics Laboratory located in Pittsburgh, 

PA.

 

The project was completed with the support of various Bayer MaterialScience employees including: 

Spray Foam Roofing & Insulation 

RJ Anderson

Terry Roye

Industrial Hygiene & Environmental Analytics Lab

Karen Mattson

Tom Frampton

Luann Bidka-Rieck

Jason Miller

Product Safety & Regulatory Affairs
9

Tim Feeley

Cathie Sayles

Brian Karlovich

BIOGRAPHIES

Author Names

Scott Ecoff is an Industrial Hygienist with the Product Safety & Regulatory Affairs group, Bayer 

MaterialScience (BMS), Pittsburgh, PA. Scott has 26 years of experience in the industrial 

hygiene field. He is a Certified Industrial Hygienist (CIH) in Comprehensive Practice (1989). 

Jim Lambach is the Head of Technology and Technical Marketing for the Spray Polyurethane 

Insulation and Roofing Materials business of Bayer MaterialScience. Jim has 24 years of

experience in the polyurethane industry, working in various capacities. 
10

Table 1

Airborne MDI Concentrations (ug/m3)

1 during Exterior Wall SPF Applications at Commercial 

Buildings

Notes:

1

ug/m3 is read micrograms per cubic meter 2

Applicator airborne concentrations shown are the average airborne MDI and pMDI (oligomer) concentrations of 2 or 3 

personal samples collected during SPF application (not the 8-hr average). Actual SPF application occurred for 

approximately 4.0 hours at each work site visited. 3

dw is read downwind

4

ND is read non-detectable less than (<) the number reported, which is the laboratory limit of quantitation (LOQ)

MDI Monomer OEL = 51 ug/m3 (8-hr TLV-TWA); Bayer recommends the same OEL for Oligomer or pMDI.

Applicator2 25 Feet Left 25 Behind 25 Feet Right 50 Feet Downwind Inside Building 

during SPF Work

Survey 

#

Monomer Oligomer Monomer Oligomer Monomer Oligomer Monomer Oligomer Monomer Oligomer Monomer Oligomer

1

CO

195 191 5.8

(dw)3

ND4 < 27

(dw)

- - - - - - ND <0.8 ND < 25

- - 4.7

(dw)

ND< 24

(dw)

- - - - - - ND <0.9 ND < 28

2

PA

31 17 6.0

(dw)

ND< 18

(dw)

1.0 ND< 19 - - 1.0 ND< 17 ND<0.5 ND< 16

- - ND<0.8

(dw)

ND< 23

(dw)

1.0 ND< 23 - - ND< 0.7 ND< 22 ND<0.6 ND< 19

3

NV

70 111 ND < 1.1 ND< 33 ND < 1.3

(dw)

ND < 38

(dw)

ND < 1.1 ND < 33 ND < 1.4 ND <43 ND< 1.1 ND< 34

ND < 1.1 ND< 32 ND < 2.5 ND < 77 ND < 1.8

(dw)

ND < 53

(dw)

-- -- ND< 1.3 ND< 38

4

TX

85 79 8.5

(dw)

ND< 22

(dw)

9.9 10.0 23.9 33.0 3.9 ND <25 14.0 13.3

23.5

(dw)

21.3

(dw)

11.4 ND< 29 18.3 14.5 2.4 ND <32 19.8 27.5
11

Table 2

Airborne Amine Concentrations (ppb)1 during Exterior Wall SPF Applications at Commercial 

Buildings

NOTES: 

1ppb is read parts per billion

2ND is read non-detectable less than (<) the number reported, which is the laboratory limit of quantitation (LOQ). 3dw is read downwind

None of the amine compounds evaluated have an OEL. 

Applicator 25 Feet Left 25 Feet Behind 25 Feet Right 50 Feet Downwind Inside Building during 

SPF work

Survey 

#

Amine

#1

Amine

#2

Amine 

#3

Amine

#1

Amine

#2

Amine 

#3

Amine

#1

Amine

#2

Amine 

#3

Amine

#1

Amine

#2

Amine 

#3

Amine

#1

Amine

#2

Amine 

#3

Amine

#1

Amine

#2

Amine 

#3

1-CO ND2

<20

ND

< 70

ND

< 11

ND

<12

(dw)3

ND

< 40

(dw)

ND

< 6

(dw)

-- -- -- -- -- -- -- -- -- ND

< 13

ND

<44

ND

< 7

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

2-PA ND

< 19

37 ND 

< 11

ND

< 17

(dw)

ND

< 19

(dw)

ND

< 10

(dw)

ND

< 20

ND

< 22

ND

< 11

-- -- -- ND

< 16

ND

< 18

ND

< 12

ND

< 14

ND

< 16

ND

< 8

ND

< 23

41 ND

< 13

ND

< 22

(dw)

ND

< 25

(dw)

ND

< 13

(dw)

-- -- -- -- -- -- ND

< 20

ND

< 23

ND

< 11

ND

< 17

ND

< 19

ND

< 10

3

NV

ND

< 31

ND

< 35

ND

< 36

ND

< 19

ND

< 21

ND

< 21

ND

< 19

(dw)

ND

< 22

(dw)

ND

< 22

(dw)

ND

< 19

ND

< 21

ND

< 21

ND

< 19

ND

< 21

ND

< 21

ND

< 22

ND

< 25

ND

< 25

ND

< 14

ND

< 16

ND

< 16

ND

< 19

ND

< 22

ND

< 22

ND

< 37

ND

< 75

ND

< 67

ND

< 18

(dw)

ND

< 21

(dw)

ND

< 21

(dw)

ND

< 19

ND

< 22

ND

< 22

ND

< 24

ND

< 27

ND

< 27

4

TX

ND

< 26

ND

< 47

ND

< 15

ND

< 17

(dw)

ND

< 31

(dw)

ND

< 10

(dw)

ND

< 17

ND

< 30

ND

< 10

ND

< 15

ND

< 27

ND

< 8

ND

< 14

ND

< 25

ND

< 8

ND

< 20

ND

< 36

ND

< 11

ND

< 23

ND

< 41

ND

< 13

ND

< 15

(dw)

ND

< 27

(dw)

ND

< 9

(dw)

ND

< 15

ND

< 27

ND

< 9

ND

< 17

ND

< 30

ND

< 9

ND

< 16

ND

< 29

ND

< 9

ND

< 17

ND

< 30

ND

< 10
12

Table 3

Airborne 1,1,1,3,3-Pentafluoropropane (245fa) Concentrations (ppm)1 during 

Exterior Wall SPF Applications at Commercial Buildings

Notes: 

1

ppm is read parts per million

2

ND is read non-detectable less than (<) the number reported, which is the laboratory limit of quantitation (LOQ) 3

dw = downwind 

AIHA WEEL = 300 ppm (8-hr TWA) for pentafluoropropane

Survey Applicator 25 Feet Left 25 Feet Behind 25 Feet Right 50 Feet Behind Inside Building 

during SPF Work

1 - CO ND2 < 2.0 ND < 1.3 (dw)3 -- -- -- ND < 1.4

2 - PA ND < 4.0 ND < 2.2 (dw)

ND < 2.8 (dw)

--

--

--

--

--

--

ND < 2.0

ND < 2.4

3 - NV ND < 4.0

6.8 

ND < 2.7

ND < 2.8

ND < 2.9 (dw)

ND < 10.1

ND < 2.7

ND < 2.9 (dw)

ND < 2.8

ND < 3.0

ND < 2.7

ND < 2.7

4 – TX 5.6

3.8

ND < 2.7 (dw)

ND < 2.7 (dw)

ND < 2.3

ND < 2.4

ND < 2.2

ND < 2.7

ND < 2.1

ND < 2.7

ND < 2.8

ND < 2.1
13