What are Isocyanates? Respiratory Protection to Consider

Isocyanates. Iso-what?? While you may not have heard of this before, it’s what makes paint stick and makes it possible to create such glossy, vibrant colors. Isocyanates are a class of highly reactive, powerful compounds that react with alcohol-based compounds to produce polyurethane polymers and certain solvent-based paints.

Painters and Foam Blowers Take Note

Jobs that may involve exposure to isocyanates are often found in applications requiring where spray painting and foam-blowing is needed such as automotive painting and other industries. Paints with isocyanate compounds are used because they adhere well, are hard and chemically resistant. They often will last a long time to wear and tear and exposure to the elements.

Exposure to isocyanates can occur during the manufacture of many polyurethane products, such as:

  • Polyurethane paint or foam, polyurethane rubber, surface coatings and adhesives
  • Insulation materials, packaging materials
  • Furniture, laminated fabrics, foam mattresses, under-carpet padding
  • Car seats and even shoes

Additionally, isocyanate exposure may occur during the welding, burning, or thermal degradation of any of these or other polyurethane coated painted products.

What are Some of the Health Effects from Isocyanate Exposure?

The health effects associated with isocyanate exposure can include skin irritation, eye irritation, chest tightness and difficulty breathing.[ii] Isocyanates also have the potential for severe adverse effects to the respiratory tract in some individuals. When spraying polyurethane paints or foam, the major hazard is dermal exposure, but workers should also avoid breathing the aerosol droplet (mist). Once the product cures, the paints contain no free isocyanates.

There is also the potential for workers to become sensitized to isocyanates.[iii] Sensitization is the body’s allergy-like response to a substance that has been inhaled or touched by a susceptible individual. These sensitized individuals may react to isocyanate exposure, even at very low levels below the occupational exposure limit that may not affect others.

PPE and Respirator Selection for Painting

After any proper engineering controls, like installing ventilation systems, have been taken to eliminate the hazardous conditions from these compounds, workers should use proper personal protective equipment (PPE), including eye protection, skin protection (gloves and coveralls) and choosing the right respiratory protection.

Respirator selection depends on issues such as the paint type (water-based, solvent-based, or powder coat), and specifically the paint contaminants and their airborne concentrations. Respiratory protection used for painting operations can include most respirator types. These options include air purifying respirators using a cartridge or filter to remove contaminants from ambient air to supplied air systems, where breathable air is provided to the wearer from a remote source, such as an industrial compressor or ambient pump.

The following is a general discussion of respirator types commonly used for painting operations.

Disposable respirators also referred to as filtering facepiece respirators, are designed primarily for aerosols (dust or spray mist). Disposable models are available with activated carbon manufactured into the facepiece, which is intended for nuisance level of organic vapors less than the occupational exposure limit, such as an OSHA PEL. Disposable respirators may be an option in some powder coating operations.

Reusable respirators also referred to as elastomeric respirators, which include tight-fitting half facepiece and, may be configured with an (e.g., organic vapor) and 95 or 100 class particle filter (N95, R95, P95, P100, etc.) for both water-based and solvent-based paints. A cartridge/filter change schedule must be implemented to determine end-of-service life based on the conditions of use. Elastomeric/reusable respirators are the most common type of respiratory protection used in painting applications.

Powered Air Purifying Respirators (PAPR) also use a cartridge to filter contaminants from ambient air. PAPR’s may be configured with tight-fitting reusable respirators, and with loose-fitting hoods and helmets. Like reusable respirators, a cartridge change schedule must also be determined for PAPR cartridges. In contrast to a tight-fitting respirator, fit testing is not required for any loose-fitting headgear. This allows use by wearers with limited amounts of facial hair. Depending on the configuration, PAPRs offer a high level of respiratory protection with Assigned Protection Factors (APF) up to 1000.

Supplied Air Respirators (SAR) may also be configured with either tight-fitting reusable respirator or loose-fitting headgear. SAR’s include both continuous flow and pressure demand types. Although a SAR does not include a cartridge or filter, breathable air must meet Grade D requirements specified by OSHA. Most supplied air respirators provide a similar level of respiratory protection as a PAPR. SARs are primarily used for solvent-based paints.

The use of NIOSH-certified respirators in workplace environments must be accompanied by a full respiratory protection program as specified in OSHA 29 CFR 1910.134. A respiratory protection program includes several points, such as written standard operating procedures, medical evaluation, fit testing (where applicable), user training, respirator cleaning and maintenance, and cartridge/filter change schedule for air purifying respirators. When selecting a tight-fitting air purifying respirator, it is very important to read and follow the donning instructions carefully and to conduct a user seal check every time the respirator is put on.

For more information on isocyanates, read our tech bulletin on OSHA’s National Emphasis Program – Isocyanates. If you paint with isocyanates, download our Industrial Paint Hazards technical data bulletin. We encourage you to contact us today with any other further questions you may have or to help you select the right PPE.

[i] https://www.osha.gov/SLTC/isocyanates/
[ii] https://www.osha.gov/SLTC/isocyanates/
[iii] https://www.cdc.gov/niosh/topics/isocyanates/default.html