Jump to main content or area navigation.

Contact Us

facebook iconLike Us on Facebook 
You are here: EPA Home » DfE » Potential Chemical Exposure from SPF and Preventative Actions

Potential Chemical Exposure from SPF and Preventative Actions

Overview of Isocyanates
Isocyanates are a class of highly reactive chemicals with widespread industrial, commercial, and retail or consumer applications.

Exposure to isocyanates may cause skin, eye and lung irritation, asthma, and “sensitization.” Isocyanates have been reported to be the leading attributable chemical cause of work-related asthma. Both dermal and respiratory exposures can trigger adverse health responses.

EPA, other federal agencies, states, industry, and other countries have taken a variety of actions to address risks posed by exposure to isocyanates.

Potential Isocyanate Exposures
Isocyanate exposures from SPF may occur through a variety of pathways.

  • Spray application generates isocyanate vapors and aerosols.  Research data indicate that inhalation exposures during SPF insulation will typically exceed OSHA occupational exposure limits (OELs) and require skin, eye and respiratory protection. The work site should be restricted to persons wearing appropriate personal protective equipment.
  • Cutting or trimming the foam as it hardens (tack-free phase) generates dust that may contain unreacted isocyanates and other chemicals.
  • Vapors and aerosols can migrate through the building if the area is not isolated and properly ventilated.
  • After application, vapors, particles of SPF insulation, and dust may linger in a building until properly ventilated and thoroughly cleaned.
  • Any heat-generating processes such as drilling, welding, or sanding of the foam insulation may generate isocyanates.
  • Fires release isocyanates, hydrogen cyanide, amines, and other toxic chemicals into the air.  Fire departments have issued advisories and require the use of full supplied air respirators when fighting polyurethane fires.

Health Risks and Alerts
Exposures to isocyanates should be minimized.  The following were noted in the NIOSH Alert, Preventing Asthma and Death from MDI Exposure during Truck Bed Liner and Related Applications .

  • Isocyanates have been reported to be the leading attributable chemical cause of work-related asthma, a potentially life-threatening disease.
  • Exposure to isocyanates can cause contact dermatitis, skin and respiratory tract irritation, sensitization, and asthma.
  • Both skin and inhalation exposures can lead to respiratory responses.
  • Isocyanates can cause “sensitization,” which means that some people may become allergic to isocyanates and could experience allergic reactions including: itching and watery eyes, skin rashes, asthma, and other breathing difficulties. Symptoms may also be delayed up to several hours after exposure. If you are allergic or become sensitized, even low concentrations of isocyanates can trigger a severe asthma attack or other lung effects, or a potentially fatal reaction.
  • Some workers who become sensitized to isocyanates are subject to severe asthma attacks if they are exposed again. Death from severe asthma in some sensitized persons has been reported. NIOSH issued an earlier Alert in 1996, “ Preventing Asthma and Death from Diisocyanate Exposure ."
  • Sensitization may result from either a single exposure to a relatively high concentration or repeated exposures to lower concentrations over time.
  • Even if you do not become sensitized to isocyanates, they may still irritate your skin and lungs, and many years of exposure can lead to permanent lung damage and respiratory problems.
  • All skin contact should be avoided since contact with skin may lead to respiratory sensitization or cause other allergic reactions. Appropriate personal protective equipment (PPE) should be used during all activities that may present exposure to any isocyanate compounds to avoid sensitization.

Hazard Communication
Consumers should obtain copies of product literature and become informed of potential health effects and safe handling procedures for chemicals and products they are using or are being used or installed in their homes by contractors. Material Safety Data Sheets (MSDSs) provide information on health effects, exposure controls, safe handling procedures, personal protective equipment, and other important information.

The Occupational Health and Safety Administration (OSHA) requires employers to develop a written hazard communication program to inform workers about the hazards and identities of all chemicals used in the workplace. The program must also address the measures needed to protect workers against adverse effects from the use, handling, and potential exposure to chemicals in the workplace. Isocyanates hazards are addressed in specific OSHA Standards and the hazard communications standard (29 CFR 1910.1200) .

Models for Exposure Prevention to Chemicals in SPF
OSHA requires that workers be trained so that they are aware of the potential hazards and follow safe work practices. No one should be permitted in the work site during installation of SPF except workers who are wearing appropriate personal protective equipment. Training should include protection of applicators, and any potentially exposed workers, including other workers at the job site or workers re-entering the job site. EPA strongly recommends that building occupants receive clear guidance from the contractor on safe re-entry times in advance of the work to ensure there will be no exposure to SPF chemicals.

  • NIOSH considers SPF insulation application to have similar hazards to other spray polyurethane applications with it calling for the same safety procedures and personal protective equipment as detailed in the 2006 NIOSH Alert, Preventing Asthma and Death from MDI Exposure during Truck Bed Liner and Related Applications .
  • In January 2008, NIOSH followed up the 2006 Alert with a poster, called “ Got Everything Covered? ,” that provides helpful tips on protecting workers from the hazards of isocyanate exposure during spray-on truck bed liner applications.
  • EPA's Design for the Environment Program, through its Automotive Refinishing Partnership , has developed numerous health and safety materials, including a Self-Evaluation Checklist of Best Practices (PDF) (18 pp, 182 KB, about PDF ), which helps businesses, vocational schools, and community colleges evaluate current practices and identify areas where improvements can be made to protect workers, students, and surrounding communities from isocyanates and other toxic chemicals. This approach provides a model for similar risk-management activities in other sectors with isocyanate exposures, e.g., spray polyurethane foam installation.
Health and Safety Information from Other Organizations
The American Chemistry Council’s Center for the Polyurethanes Industry (CPI) and the Spray Polyurethane Foam Alliance (SPFA) have developed communication and product stewardship materials targeted to SPF professionals and posted them on their spray polyurethane foam: health and safety Exit EPA Disclaimer site.

Isocyanate Compounds Commonly Used in SPF and related products
Isocyanates are chemical substances containing an isocyanate (-N=C=O) functional group. Diisocyanates have two isocyanate functional groups. Other isocyanates contain several isocyanate groups. There is concern for exposure to any isocyanate-containing material related to SPF use, including products that contain only a single isocyanate.

The most common isocyanate compounds used in SPF are listed in the table below. SPF contains MDI and MDI-based polyisocyanates. There are numerous chemical names and synonyms for members of the class of isocyanates and the list below is not all-inclusive.

Chemical Name CAS Number
4,4'-Methylene diphenyl diisocyanate (MDI) 101-68-8
Polymeric Diphenylmethane Diisocyanate (pMDI) 9016-87-9
Diphenylmethane Diisocyanate Mixed Isomers 26447-40-5
2,4'-MDI 5873-54-1
2,2'-MDI 2536-05-2
Generic MDI 26447-40-5
4,4'-MDI homopolymer 25686-28-6
Generic MDI homopolymer 39310-05-9
4,4'-MDI dimer 17589-24-1
Uretonimine of 4,4'-MDI 31107-36-5
4,4'-MDI/ 2,4'-MDI copolymer 109331-54-6

The world production-volume of isocyanates Exit EPA Disclaimer is estimated to be in excess of six million tons annually with growth of 10 to 15 percent annually.  The most widely used isocyanates are:

  • Methylene diphenyl diisocyanates (MDI)
  • Toluene diisocyanates (TDI)
  • Hexamethylene diisocyanates (HDI)
  • MDI-, TDI-, and HDI-based isocyanates

Isocyanates have a broad range of uses in the manufacture of consumer products, including:

Spray applications of isocyanates may generate aerosols, mist, and vapors that can be inhaled or come in contact with the eyes or skin. Potential exposures may occur through skin contact or inhalation of particulates and dust particles containing isocyanates.

Top of page


Material Safety Data Sheets (MSDS) and Product Literature

Ask your retailer or distributor to provide you product literature as well as the Material Safety Data Sheets (MSDS) for the material you are using. MSDSs can also be found on the product manufacturer website.  You can also search the U.S. Department of Health and Human Services’ Household Products Database.


Preventative Actions

Carefully review product ingredients and use information, such as material safety data sheets (MSDSs), to determine the appropriate practices that applicators should follow when using the product.

Isolate SPF installation area.

Avoid exposure without the use of appropriate personal protective equipment (PPE), including gloves, respirators, and protective clothing. Any two-component spray applicators should wear supplied air respirators.  All applicators and other workers in the area should wear appropriate PPE.

During SPF installation, residents and other unprotected building occupants should vacate the premises until after the foam is applied, cured, trimmed, and the area has been thoroughly cleaned to eliminate any residual isocyanates and ventilated. Some manufacturers recommend 23 to 72 hours before re-occupancy for two-component applications and 6 to 12 hours for one component foam applications, but re-entry time is dependent on product formulation and other factors.


Printable version (PDF) (1 pg, 88KB, about PDF )


SPF Safety Tips for Weatherizing with Spray Foam Postcard
Picture of postcard of safety tips for weatherizing with spray foam.

Download a postcard of Safety Tips for Weatherizing with Spray Foam (PDF) (2 pg, 477 KB)

Jump to main content.