Environmentally friendly doesn’t necessarily mean worker friendly. In many cases, new “green” technologies and products have reached the market without being adequately evaluated to determine whether they pose health or safety risks to workers in manufacture, deployment, or use. Spray polyurethane foam—commonly referred to as SPF—is a case in point. Its use as insulation has been on the upswing because of the laudable aim of builders and property owners to improve energy efficiency. As popular as it has become, however, much remains unknown about spray polyurethane foam—specifically the health implications of its amines, glycols, and phosphate upon workers.
Polyurethane foam has a high R-factor (or R-value), so it resists the flow of heat and, when used as insulation, increases a building’s energy efficiency. Because of this, it has become a favorite in the world of energy-conscious construction and renovation. While better insulation clearly means less energy consumption, what’s not clear is the level of protection and ventilation workers need so that they remain safe during the installation process.
MDI: The known hazard
Spray polyurethane foam is applied as a liquid but expands as it dries. The product itself is a two-component system. The first chemical in the mixture is methylene diphenyl diisocyanate (MDI). The hazards of MDI are well-documented and their exposure limits have been established However, the known hazards for spray polyurethane foam only take into account the first part of the mixture—the MDI.
Amines, glycols, and phosphate: Unknown risks
The other half of the mix has not been studied for worker safety. It is a chemical question mark with no toxicology or health information. This part contains amines, which act as a catalyst; glycols—blowing agents that react with the foam; and phosphate, a flame retardant. This half of the spray polyurethane foam equation raises several questions:
- What is the concentration of the fumes and vapors from these chemicals when spray foam is applied?
- Are the workers who are applying the spray foam adequately protected?
- What about others on site who are not applying the spray foam and who are not wearing the same personal protective equipment?
- How long does it take to ventilate the area after application?
- Are there cost-saving methods for isolating and venting the fumes?
A need for real-world air sampling
We are currently researching these issues. In our labs we’ve done tracer gas studies, simulating potential exposures to spray polyurethane foam components, but to make the science useful for SPF installers, we need partners to help us collect on-site air samples. At the worksite, we will collect personal breathing-zone air samples and set up five tripods with air-sampling pumps to obtain readings in a variety of sampling areas. We would like to gather samples during the spray foam application, and again at intervals afterwards. The data we collect will help us gauge:
- The true level of personal protective equipment needed by the worker applying the spray foam and by those who are elsewhere on the worksite.
- The actual amount of time before the area is void of harmful levels of vapors. The idea that the area needs to be clear for 24 hours is anecdotal and has no scientific underpinning.
- Proper ventilation and cordoning of the spray foam work area. Some contractors go to great lengths to tape and plastic the room; others do nothing at all. Our air sampling will clarify what the best practice is.
Additionally, we are working on a portable spray booth that will contain overspray fumes and improve ventilation—a cost-saving intervention.
A need for solid science
It’s difficult for even the most conscientious employers to protect their workers because limited data exist on the second part of the spray foam mixture. The popularity of the product and the number of companies using it demands that there be some scientific background informing its use.
Please contact NIOSH to advance the science behind spray polyurethane foam insulation. You can reach us through this blog. While foam insulation may be green, with your help, our research can ensure that spray foam is sustainable for your workers as well.
—David A. Marlow, BS
Mr. Marlow is an industrial hygiene engineer in the NIOSH Division of Applied Research and Technology.