cartridge filter of the air pump is sent to the lab to obtain results. Hierarchy of Controls Guth presented an inverted pyramid called the “Hierarchy of Controls” that lists methods from top to bottom according to how effective methods are in protecting workers. Guth pointed out that elimina- tion and substitution are the most effective methods of protecting workers, but are also the most difficult to implement unless the process is in the design stages – then elimination and substitution of hazards may be inexpensive and simple to implement. Here’s why this elimination and substitution are effective but not desirable: “An example of elimi- nation would be to withdraw the ceramic tile from the project, and there would be no silica expo- sure from cutting,” Guth said. “However, we do not want to see tile eliminated from projects. An example of substitution would be to substitute VCT for ceramic tile, and there would be no silica exposure from cutting.” Again, that would not be a desirable goal for the tile industry.” Engineering controls, such as wetting down work operations or using local exhaust ventilation (vacuums) or “process isolation” – enclosing an operation – are preferred over personal protective equipment (PPE) because they are designed to remove the hazard at the source – before it comes in contact with the worker. Administrative controls and PPE are often used with existing pro- cesses where hazards are not well controlled. These measures can be relatively inexpensive to imple- ment but costly to maintain in the long run. Because they require sig- nificant effort by affected workers, they also are less effective than the measures higher up in the pyramid. For instance, one example of an administrative control would be to limit the number of hours per day a person performs a work practice with silica exposure, Guth said. “Creating controlled access zones where a hazardous environ- ment exists is another example. This could be closing off a room or a portion of a building where someone is chipping or grinding on a concrete floor. “Administrative controls and PPE are considered the least desir- able methods of control by OSHA and should be viewed as a last TECH TALK –––––––––––––––––––––––––––––––––––––––––––––––––––––––––– 68 TileLetter | June 2018