In recent years, spray polyurethane foam (SPF) insulation has become increasingly popular in both residential and commercial construction. More energy efficient than traditional fiberglass insulation, SPF insulation is used to create a moisture and vapor barrier in perimeter walls, crawl spaces and attics.

However, despite claims from manufacturers that SPF is “green” or “environmentally friendly,” the same can’t be said of its effects on workers. SPF insulation contains chemicals called isocyanates that can cause skin and lung sensitization as well as irritation to the skin and mucous membranes like the eyes. Sensitization means that workers can develop an allergy to a certain chemical after being exposed to it. Once sensitized, workers can quickly develop asthma, even if they have never had symptoms before. The following symptoms can appear during or immediately after exposure to isocyanates:

• Wheezing, shortness of breath, coughing
• Irritation of the eyes and lungs
• Fever
• Stuffy nose
• Sore throat
• Tightness in the chest

Once the lungs or skins are sensitized, it’s possible for symptoms of asthma to be triggered by exposure to everyday substances such as dust or cold air. It’s estimated that between 15-30 percent of asthma in adults is caused by occupational exposures. Isocyanates have been reported as the leading chemical cause of work-related asthma.

Workers are most commonly exposed to isocyanates in SPF by breathing them in or getting them on their skin during the installation process. Until polyurethane products such as spray foam harden or cure completely, they can still release isocyanates. Once cured, polyurethane products can release isocyanates if they are heated, burned, cut or abraded. Workers should also be aware that isocyanate exposures can occur from adjacent areas – the harmful chemicals in SPF have been shown to travel throughout large buildings during installation.

Working Safely Around Isocyanates

Controlling and eliminating on-the-job exposures to chemical sensitizers such as isocyanates requires putting the proper protections in place. Employers should consult the safety data sheet (SDS) for any product that could contain isocyanates and find safer substitutes if possible. Barring that, employers can use ventilation to reduce the concentration of isocyanates in the air, restrict access to areas where isocyanates are present and provide appropriate personal protective equipment (PPE).

Workers using products containing isocyanates should wear the following PPE to protect themselves from exposure:

• Cover all exposed skin by wearing a disposable dust suit
• Wear neoprene, nitrile or butyl rubber gloves
• Wear chemical safety goggles to protect the eyes
• Use a self-contained breathing apparatus (SCBA) or a powered air-purifying respirator (PAPR) when isocyanate-containing materials are being heated or sprayed

When using respirators to protect against exposure, always use an organic vapor cartridge and change it regularly. Because isocyanates are odorless and colorless, they don’t present warning properties to alert workers of exposure. NIOSH has documented several case studies of workers who have died from acute exposure to isocyanates.

What to Do If You’ve Been Exposed to Isocyanates

Developing work-related asthma could make working on some kinds of job sites difficult – jeopardizing or cutting short a career in the construction industry. Permanent asthma can develop as quickly as a few hours after exposure to isocyanates depending on the level of exposure and an individual’s sensitivity. If you think you may have work-related asthma, see your doctor as soon as possible. Bring copies of any available safety data sheets along with this OSHA factsheet, which was designed to be shared with your health care provider.

For further information on isocyanates, visit OSHA’s Isocyanates page. California’s Department of Public Health created this guide about work-related asthma, which includes information on isocyanate exposures in other industries such as construction, hospital work and custodial work.

[Nick Fox]