As a result, the operation of these units may have adversely impacted the indoor air quality at each school. Another concern noted was the practice of introducing synthetic materials such as plastic or mothballs during the firing process as a means to create a new or unique lustre on the ceramic piece. Mothballs and stryofoam are examples of some of the synthetic materials that may be introduced during the firing process to develop a unique lustre. This is reported to be a common practice among ceramic artisans as a means to develop and express an artistic signature. A hazard associated with ceramics but unrelated to the operation of kilns is the generation of free silica.
Free silica is a concern because it is physically similar to asbestos.
In addition, free silica is a severe respiratory hazard. As a result, efforts should be made to minimize the amount of dust generated while preparing ceramic pieces. Furthermore, all dust generated by these activities should be assumed to contain free silica and should only be cleaned up via damp mopping. Sweeping or vacuuming could re-suspend the free silica and increase the respiratory hazard posed by this material. The introduction of various synthetic materials into the kilns during firing may have resulted in the generation of highly toxic emissions.