Performance of sulfur dioxide passive monitors

The following four commercial sulfur dioxide passive monitors were tested for performance and realiability: DuPont Pro-Tek C-20 air monitoring badges; MSA Vaporgard Dosimeter tubes; REAL BioBadges; and 3M Sulfur Dioxide Nutshell monitors. The experiments conducted were designed to test factors critical to the operation of passive samplers: accuracy and precision; capacity; stability; analytical recovery; and the effects of exposure time, concentration, humidity, face velocity, orientation, chemical interference, and temperature. The DuPont Pro-Tek badges performed satisfactorily for all the factors tested, and the REAL BioBadges performed satisfactorily except for the instability of the SO2/tetrachloromercurate complex when stored. An alternate monitoring system, REAL BioBadges containing deionized water absorbent had a limited capacity. Only the MSA dosimeters exhibited unsatisfactory performance. The 3M Nutshell monitor was withdrawn by the manufacturer after only partial evaluation.