First Sentence

"The MAK value ("maximale Arbeitsplatz-Konzentration": maximum workplace concentration) is defined as the maximum concentration of a chemical substance (as gas, vapour or particulate matter) in the workplace air which generally does not have known adverse effects on the health of the employee nor cause unreasonable annoyance even when the person is repeatedly exposed during long periods, given a 40-hour working week (or 42-hour when averaged over four weeks in firms with four work shifts)."