Saf Health Work.  2022 Sep;13(3):357-363. 10.1016/j.shaw.2022.04.005.

Occupational Exposure to Refractory Ceramic Fibers in the Semiconductor Scrubber Manufacturing Industry

• Song S
• Kim S
• Kim D
• Yoon C

• KMID: 2533591
• DOI: http://doi.org/10.1016/j.shaw.2022.04.005

Abstract

Background
Refractory ceramic fibers (RCFs) are a suspected carcinogen but have been widely used as insulations. Depending on the temperature, RCFs can transform into crystalline SiO₂, which is a carcinogen that can be present in the air during bulk RCF handling. This study analyzed the physicochemical and morphological characteristics of RCFs at high temperatures and determined the exposure levels during the semiconductor scrubber maintenance.
Methods
Sampling was conducted at a company that manufactures semiconductor scrubbers using RCFs as insulation. Bulk RCF samples were collected both before and after exposure to a scrubber temperature of 700°C. Airborne RCFs were collected during scrubber maintenance, and their characteristics were analyzed using microscopes.
Results
The components of bulk RCFs were SiO₂ and Al₂O₃, having an amorphous structure. Airborne RCFs were morphologically different from bulk RCFs in size, which could negatively affect maintenance workers’ health. 58% of airborne RCFs correspond to the size of thoracic and respirable fibers. RCFs did not crystallize at high temperatures. The exposure caused by airborne RCFs during the scrubber frame assembly and insulation replacement was higher than the occupational exposure limit.
Conclusion
Workers conducting insulation replacement are likely exposed to airborne RCFs above safe exposure limits. As RCFs are suspected carcinogens, this exposure should be minimized through prevention and precautionary procedures.

Keyword

Exposure assessment; High-temperature insulation; Occupational exposure; Refractory ceramic fibers; Work environment