Mark H. Midddlebrook

How to Avoid Exposure to Isocyanates

dangers of inhaling isocyanatesIsocyanates are a family of highly reactive, low molecular weight chemicals. They are widely used in the manufacture of flexible and rigid foams, fibers, coatings such as paints and varnishes, and elastomers, and are increasingly used in the automobile industry, auto body repair, and building insulation materials. Spray-on polyurethane products containing isocyanates have been developed for a wide range of retail, commercial, and industrial uses to protect cement, wood, fiberglass, steel and aluminum, including protective coatings for truck beds, trailers, boats, foundations, and decks.

Hexamethylene diisocyanate, commonly known as isocyanates, is used as a polymerizing agent in polyurethane paints and coatings. Short-term exposure to high concentrations of hexamethylene diisocyanate in humans can cause:

  • pulmonary edema
  • coughing
  • shortness of breath
  • eye, ear, & nose irritation
  • chronic lung problems
  • and more…

IMPORTANT:Exposure risk is cumulative and causes long-term exposure effects.

To achieve compliance administrative or engineering controls must be implemented whenever feasible. When such controls are not feasible to achieve full compliance, protective equipment or other protective measures shall be used to keep the exposure of employees to air contaminants within the limits prescribed in this section.

Below is an example of implementing an engineering control: the AirVerter CAPS II fitted with a SharpShooter tool. The permissible exposure limits (PEL) are .0005. The results using the CAPS II system was <0.00072 ppm below the detection limit (BDL) of the analytical method.

Sample Number Compound 8-hr Time Weighted Average (TWA)***mg/m3 CAL/OSHAPermissible Exposure Limit (PEL)**mg/m3 CAL/OSHA PELExceeded Yes/No
KT10021-1personal sample Hexamethylene diisocyanate <0.00072 ppm (BDL)* 0.005 ppm No
KT100211-2area sample at exhaust line Hexamethylene diisocyanate <0.00072 ppm (BDL)* 0.005 ppm No

*BDL-Below the detection limit of the analytical method

**Permissible Exposure Limit: The permissible concentration in air of a substance to which nearly all workers may be repeatedly exposed 8 hours a day, 40 hours a week, for 30 years without adverse effects.

***TWA-Time Weighted Average-the airborne concentration of a contaminant averaged over the work period usually 8 hours


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