News Brief

Field Research to Provide Deeper Look at Spray-Foam Risks

Exposure to MDI in spray foam is a known risk, but what about other chemicals? And is that 24-hour re-entry period based on science?

NIOSH hopes more data on the full impacts of spray-foam could inform more effective safety procedures in the workplace.

Credit: Steve Becker. License: CC By 2.0
The National Institute for Occupational Safety and Health (NIOSH) is asking installers to help with onsite air sampling to facilitate ongoing research of the lesser-known chemicals in spray polyurethane foam (SPF)—a product valued in energy-efficient construction for airtightness and insulating value, but which has been under a cloud of concern about health effects.

Installers are supposed to take precautions while installing SPF because of the known health effects of methylene diphenyl diisocyanate (MDI)—a chemical that is a powerful irritant to mucous membranes, causing chemical sensitivity and asthma. However, other chemicals in the SPF mixture have not been as extensively studied and may come with exposure risks of their own.

NIOSH is attempting to fill that knowledge gap by researching the concentrations of amines, glycols, and phosphates released into the air as spray foam is installed and measuring how long they persist. In addition to lab studies, NIOSH is asking SPF installers to allow researchers access to jobsites so that they can gather air samples.

This research may provide the basis for more comprehensive worker safety procedures and will offer more data to determine safe re-entry times. NIOSH calls the 24-hour rule of thumb now common in the construction industry “anecdotal” with “no scientific underpinning.” It may also inform the development of a new “portable spray booth” that NIOSH hopes may improve ventilation at a lower cost.

Published September 30, 2013

Pearson, C. (2013, September 30). Field Research to Provide Deeper Look at Spray-Foam Risks. Retrieved from

Add new comment

To post a comment, you need to register for a BuildingGreen Basic membership (free) or login to your existing profile.


October 7, 2013 - 3:57 pm

I should have said that the NIOSH study was probably not needed and was misleading. The TLV for MDI is 0.05 mg/ m3 or 5 ppb. This is very very low. the material has a small VP so air borne exposure is from spraying or extreme agitation. If you control for MDI then unless they have Be or radioactive ingredients - good ventilation and full face supplied air respirators (with good program) will suffice. Residents need to leave for 24 hrs .
NIOSH can simply ask the mfgs for the list and amount of all the other ingredients. NIOSH has the right to any trade secrets. While i do not know the full composition it is hard to imagine any other ingredients that need to be controlled to such a low level as MDI from spray activities. So this study can be done in on paper in an hr.

October 7, 2013 - 2:59 pm

William, can you provide any data to back up the statement that protecting for MDI protects for other chemicals? How do we know that there aren't other chemicals with exposure limits that would need to be tighter, or dealt with differently? A lack of data on this seems to be what NIOSH is trying to get at.

The article is reporting on NIOSH's work -- if you don't like what they're doing, let them know, but I don't see how the article is misleading.

Tristan Roberts
Editorial Director

October 7, 2013 - 2:45 pm

the permissible exposure limit for MDI is so low that if you protect for that - you protect for any other chemical in the package- mostly some low tox solvents and surfactants. i think this article is misleading.. i do not see the risk.