Fig. 6
From: Engineered nanomaterials: toward effective safety management in research laboratories
Matrix combining duration and frequency of operation for powder handling. Distribution of typical durations of operations in minutes (abscissa) in relation to the number of days of work in a year (ordinate). The numbers in the matrix are obtained as a product of the duration time (as a percentage of the 8 h working time) and number of days of work per year. Three classes of duration–frequency are set in green, orange, and red