Narcogun MC-339 Spray Fireproofing

Product Description

Narcogun MC-339 was a spray-applied fireproofing material manufactured by Narco during the period spanning 1965 through 1975. Products in this category were engineered to provide passive fire resistance to structural components, most commonly steel beams, columns, and decking found in commercial and industrial construction. Spray-applied fireproofing of this era was a standard feature of large-scale building projects, where building codes and insurance requirements mandated that structural steel be protected against heat-induced deformation or collapse in the event of a fire.

The Narcogun MC-339 product was applied using specialized spray equipment—a method that was valued for its speed and ability to coat irregular or complex structural shapes that would have been difficult to protect through other means. This spray application process allowed crews to quickly cover large surface areas of structural steel, making products like MC-339 popular on industrial job sites, warehouses, manufacturing facilities, and similar large-footprint construction projects throughout the decade of its production.

Narcogun MC-339 belonged to a broader class of cementitious or fibrous spray fireproofing materials that were widely adopted across the construction industry during the 1960s and 1970s. The use of asbestos as a reinforcing and insulating agent in these formulations was common practice during this period, reflecting the building industry’s reliance on asbestos-containing materials before the health hazards of asbestos exposure were widely understood and regulated.

Asbestos Content

Narcogun MC-339 contained chrysotile asbestos as a component of its formulation. Chrysotile, also known as white asbestos, is a serpentine-form asbestos fiber and was the most commercially prevalent form of asbestos used in construction products throughout the mid-twentieth century. Its fibrous structure and thermal resistance properties made it a practical additive for fireproofing products intended to withstand high heat.

In spray-applied fireproofing materials, asbestos fibers served multiple functional roles. They contributed tensile strength to the applied coating, helped bind the material to structural surfaces, and provided the thermal insulating properties that gave the product its fire-resistant characteristics. The chrysotile fibers were mixed into the product’s base formulation and were released as airborne particulate during the spray application process, during any disturbance of the cured material, and during removal or remediation work.

Chrysotile asbestos, while sometimes characterized in industry literature as less hazardous than amphibole forms of asbestos such as crocidolite or amosite, is classified by the Environmental Protection Agency (EPA), the Occupational Safety and Health Administration (OSHA), and the International Agency for Research on Cancer (IARC) as a known human carcinogen. No safe level of occupational asbestos exposure has been established for any fiber type. The Asbestos Hazard Emergency Response Act (AHERA) and OSHA’s asbestos standards apply to chrysotile-containing materials without distinction from other asbestos types.

How Workers Were Exposed

Industrial workers represent the primary population documented as having been exposed to airborne asbestos fibers from Narcogun MC-339 during its production years. Exposure pathways associated with this type of spray fireproofing product were significant, varied, and often continuous over the course of a worker’s career.

During Application: The spray application of MC-339 was an inherently dusty process. Compressed air forced the wet mixture through spray nozzles, generating clouds of fine particulate that included asbestos fibers. Workers operating spray equipment were in direct and sustained proximity to this aerosol. Because job sites during this era frequently lacked adequate ventilation controls or respiratory protection programs meeting modern standards, airborne fiber concentrations during active spraying could reach levels far exceeding what is now recognized as safe.

Bystander Exposure: Industrial worksites are shared environments. Workers in trades adjacent to spray fireproofing operations—electricians, pipefitters, ironworkers, and general laborers working in the same area—were exposed to asbestos-laden dust even when they had no direct involvement in applying the product. This secondary or bystander exposure is well documented in the occupational health literature as a significant route of asbestos-related disease.

Disturbance of Cured Material: Once applied and dried, the cured MC-339 coating remained a source of potential fiber release whenever it was disturbed. Drilling, cutting, breaking, or otherwise impacting the hardened material during renovation, repair, or demolition work released previously bound chrysotile fibers back into the air. Workers involved in any modification of structures where MC-339 had been applied years earlier faced exposures that could equal or exceed those at initial application.

Maintenance and Remediation Work: Industrial facilities built or renovated during the 1965–1975 production window often retained their original fireproofing coatings for decades. Maintenance workers who accessed ceiling spaces, structural areas, or mechanical rooms containing deteriorating MC-339 were at continued risk. Asbestos abatement workers and contractors hired to remove the material faced concentrated fiber releases during encapsulation or full removal procedures.

Protective equipment and exposure controls available to workers during the 1965–1975 period were generally inadequate by the standards later codified by OSHA in its 1971 asbestos standard and significantly strengthened regulations thereafter. Many workers applied or worked around products like Narcogun MC-339 without respirators, disposable coveralls, or any formal hazard communication informing them of the risks associated with asbestos inhalation.

Documented Trust Fund / Legal Options

Trust Fund Status: No dedicated asbestos bankruptcy trust fund has been established for claims arising from Narcogun MC-339 manufactured by Narco. Individuals seeking compensation for asbestos-related illness connected to this product do not have a trust fund filing pathway available to them through Narco’s manufacturer directly.

Litigation Record: Narcogun MC-339 has appeared in asbestos personal injury litigation. Litigation records document claims brought by industrial workers and others alleging exposure to asbestos-containing spray fireproofing products, including MC-339. Plaintiffs alleged that exposure to chrysotile asbestos released during the application, disturbance, or removal of this product caused serious asbestos-related diseases, including mesothelioma, asbestosis, lung cancer, and other pulmonary conditions.

Plaintiffs alleged that Narco and related parties knew or should have known of the hazards associated with asbestos inhalation during the period of MC-339’s production, and that adequate warnings were not provided to workers who used or worked around the product.

Legal Remedies Available: Individuals diagnosed with mesothelioma, asbestosis, lung cancer, or other asbestos-related diseases who have documented occupational exposure to Narcogun MC-339 may have grounds to pursue civil litigation against responsible parties. Because multiple manufacturers, contractors, and premises owners are often named in asbestos litigation, compensation may also be available through claims against other solvent defendants or existing asbestos trust funds established by other companies whose products were present on the same job sites.

Workers and surviving family members are encouraged to consult an attorney experienced in asbestos litigation to evaluate their exposure history and legal options. Statutes of limitations for asbestos claims vary by state and typically begin running from the date of diagnosis rather than the date of exposure, but prompt consultation is advisable to preserve legal rights.