(1976 ) The concentrations of sulfur dioxide were measured under the negative pressure filtering respirator with elastomeric half mask, and in the breathing zone ( simultaneously ); and the results were used to calculate the respirator protection factors PF ( such as the concentration ratio, ambient to in-facepiece ).
12.
The directive defines "'occupational exposure limit value "'as " the limit of the time-weighted average of the concentration of a chemical agent in the air within the breathing zone of a worker over a specified reference period . " Article 3 of the directive led to the creation of the Scientific Committee on Occupational Exposure Limit Values to advise the European Commission.
