“The philosophical basis for the hierarchy of controls is hazard control at the source or as close to the source as possible. The epitome of source control is elimination of the hazard or substitution with a less hazardous or nonhazardous substance.”1
“Administrative controls are policies aimed at limiting worker exposure to a hazard, typically by altering the amount of time a worker is potentially exposed and by the implementation of good work practices.”1
“Use of personal protective equipment (PPE) such as respirators, gloves, and protective clothing is the least preferred method for preventing worker exposure to a hazard because it places the responsibility for preventing injury or illness on the worker.”1
1. P. Schulte, C. Geraci, R. Zumwalde, M. Hoover, and E. Kuempel, “Occupational Risk Management of Engineered Nanoparticles,” Journal of Occupational and Environment Hygiene 239, 243-244 (April 2008)