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Potential Chemical Exposures From Spray Polyurethane Foam

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Possible exposure routes

When spray polyurethane foam is being used, the work site should be restricted to persons wearing appropriate personal protective equipment. The information on this page is meant to underline the importance of wearing protective equipment by explaining ways that chemical exposures from spray polyurethane foam (SPF) may occur. 

Vapors and aerosols

  • Spray application generates isocyanate vapors and aerosols.
  • Research data indicate that inhalation exposures during SPF insulation will typically exceed Occupational Safety and Health Administration (OSHA) occupational exposure limits (OELs) and require skin, eye and respiratory protection.
  • Vapors and aerosols can migrate through the building if the area is not isolated and properly ventilated.
  • After application, vapors may linger in a building until properly ventilated and thoroughly cleaned.


  • Cutting or trimming the foam as it hardens (tack-free phase) may generate dust that may contain unreacted isocyanates and other chemicals.
  • After application, dust may linger in a building until properly ventilated and thoroughly cleaned.

Heat-generating processes


  • Fires involving SPF may 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.

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“Curing” of SPF means that the chemicals in the product are reacting to produce polyurethane foam. SPF material is highly adhesive and will stick to most surfaces. SPF may appear hardened or "tack-free" within a range of a few seconds to a few minutes after application.  However, at this stage, the foam is still curing and still contains unreacted SPF chemicals.

Some manufacturers recommend 24 hours after application for the two-component high pressure "professional" SPF system for worker re-entry without the use of PPE and for re-occupancy by residents and other building occupants, but the recommended time may vary.

Contact your manufacturer or supplier for specific guidance on ventilation time, re-entry time, and re-occupancy time for your specific product and scenario. Some manufacturers estimate that it can take approximately 8 to 24 hours to cure for one component foam, typically available in 12 oz. to 24 oz. cans.

More research is needed to account for the potential variability of curing rates.

Get more information on ongoing research on re-occupancy times, product emissions, and ventilation rates through ASTM International Subcommittee D 22.05 on Indoor Air Quality. Exit

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Curing rates of SPF affect re-entry times

The curing time (complete reaction) varies depending on the type of SPF product, product formulation, applicator technique, foam thickness, temperature, humidity and other factors. Together, these factors will impact re-occupancy time. Exit Cutting or trimming foam before it is fully cured may cause exposure to unreacted SPF chemicals.

The polyol blend (B-side) contains a variety of proprietary chemicals and curing rates may vary for different SPF product formulations. Read the manufacturer’s recommendation in the material safety data sheet (MSDS) and other product information for all types of SPF products and applications.

Air sampling and testing the indoor air following SPF installation is one way to assure the foam is completely cured. Emissions testing of SPF foam applied in a laboratory and in the field (at the work site) may vary.

Testing should be conducted by a certified laboratory using a validated method such as the Standard Method for the Testing and Evaluation of Volatile Organic Chemical Emissions from Indoor Sources Using Environmental Chambers, Version 1.1 (2010) (PDF) (52 pp, 429 K) Exit under California Section 01350 Exit.

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Long-term concerns for exposure potential

After spray foam is applied and cured, it is considered to be relatively inert; however, there are several situations where the cured foam may pose additional potential risks.

  • Maintenance workers, including plumbers and electricians, should not heat or grind spray foam. Spray foam can potentially generate toxic emissions under these circumstances.
  • Building renovations, demolition, or building disassembly done years later can disturb spray foam insulation. Performing hot work on or near polyurethane foam may lead to potential exposures to isocyanates and other toxic emissions.

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Potential off-gassing

The potential for off-gassing of volatile chemicals from spray polyurethane foam is not fully understood and is an area where more research is needed. Standardized methods are needed to assess the potential impacts of SPF insulation products on indoor air quality and to establish re-entry or re-occupancy times after product installation in a building and to better understand post-occupancy ventilation needs, such as through HVAC considerations during the planning phases before SPF or other insulation is installed. Remember, insulation is intended to seal a residence and can significantly decrease air exchanges, emissions from SPF and other products, including combustion sources, can build up in a building.

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One method for measuring volatile chemicals is the standard method under California Section 01350.

ASTM International, an organization that sets standards for products and materials, has initiated development of a series of proposed standards under the Indoor Air Subcommittee (D22.05) to determine volatile organic compounds, diisocyanates, oligomeric isocyanates, and amine catalysts emitted from SPF insulation products designed for on-site application in buildings. The subcommittee is working on additional SPF-related work items (proposals) and standards to develop methods to measure emissions from SPF. Read the ASTM standards for SPF.

The subcommittee recently developed D7859—Standard Practice for Spraying, Sampling, Packaging, and Test Specimen Preparation of Spray Polyurethane Foam (SPF) Insulation for Testing of Emissions Using Environmental Chambers to standardize spraying, sample preparation, and packaging. Read the subcommittee's standard practices for SPF.

The ASTM Subcommittee hosted a symposium on SPF methods in April, 2015, bringing together experts from industry, academia, indoor air professionals, air quality consultants, testing labs, and government to exchange ideas on research needs, methods development, and the development of standards.

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Should I take action or remove SPF that has been installed?

If home or building occupants have concerns that they may be exposed to residual SPF chemicals, potential off-gassing, or continue to smell odors, consider the following:

  • Work with the contractor to identify the problem or consider hiring an independent expert such as a qualified Indoor Air Quality (IAQ) consultant to diagnose sources of indoor air issues.
  • If you experience breathing problems or other adverse health effects, seek immediate medical attention.
  • Contact the contractor and/or product manufacturer to request help in solving the problem if the SPF material is shown to be the source of the problem.
  • If concerns are not resolved with the contractor and/or product manufacturer, affected parties should contact their local or state consumer protection office or contractors’ licensing board.
  • Consumers can, and should, file an online Consumer Product Incident Report with the U.S. Consumer Product Safety Commission on the website if SPF material is considered to be the source of a problem.
  • EPA is not currently aware of standard accepted removal and/or remediation practices. This is an area for further investigation and research as future renovation and deconstruction of buildings where SPF has been applied are anticipated.
  • Note: Removal may not resolve the problem and may create other problems.

When spray foam has been correctly applied and cured, it is usually considered to be relatively inert. There are, however, factors that impact curing rates and some long-term concerns for exposure potential.

If SPF was not applied properly, chemical contaminants may have migrated to hard and/or soft surfaces elsewhere in the building and may be the source of residual odors; therefore, removal may not resolve the issue. Also, disturbing SPF material might generate dust or hazardous materials if done improperly, especially if using processes that might heat (PDF) (3 pp, 443 K) Exit these materials.

Before you renovate or have other activities done in your home or building, find out whether SPF is present. Consider following the guidance on re-occupancy and other steps to control exposures, such as clean-up and ventilation practices.

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