Standard ozone monltorlng technlques utlllze large, heavy, and expenslve Instruments that are not easlly adapted for personal or mlcroenvlronmental monltorlng. For largescale monltorlng projects, where spatlal varlatlons of a pollutant and human exposure assessments are of Interest, passlve sampllng devlces can provide the methodology to meet monltorlng and statlstlcal goals. Recently we developed a coated fllter for ozone collectlon that we used In a commerclally available passive sampllng devlce. Results from the ozone sampler valldatlon tests are presented. The paoslve ozone sampler used In fleld and laboratory experlments consists of a badge clip supportlng a barrel-shaped body whlch contalns two coated glass flber fllters. The principal component of the coatlng is nltrlte Ion, which In the presenceof ozone Is oxldlzed to nltrate Ion on the fllter medlum, N01-+ 0 3 -NOS-+ 0 2 .After sample collectlon, the filters are extracted wlth ultrapure water and analyzed for nltrate Ion by Ion chromatography. The results from laboratory and fleld valldatlon tests lndlcate excellent agreement between the paslve method and standard ozone monltorlng technlques. We have determined that relative humldlty (ranglng from 10 to 80%) and temperature (ranglng from 0 to 40 "C) at typlcal amblent ozone levels (40-100 ppb) do not Influence sampler performance. Face veloclty and sampler orlentation with respect to wlnd dlrectlon affected the sampler's collectlon rate of ozone. By using a protectlve cup which acts as both a wlnd screen and a raln cover, we were able to obtain a constant collectlon rate over a wlde range of wlnd speeds.

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A passlve sampler was developed for short-term, low-level air monltorlng applications. The small, Stainless steel devlce Is simply designed and Inexpenslve. I t has a hlgh equlvalent sampling rate, Is reusable and rechargeable, and Is designed for thermal desorptlon. Laboratory and field tests wlth Tenax GC as the sorbent have shown that the device compares very favorably wlth active (pump-based) samplers and has much better sensltlvlty than commercial passive monltors which utlllze actlvated charcoal. Performance was examlned under controlled test chamber atmospheres and In actual outdoor and Indoor sltuatlons. Sampling rates were calculated for several volatlle organlc chemlcals. An extensive evaluation of the effects of alr veloclty on performance also was undertaken.Most passive sampling devices (PSDs) function on the basis of molecular diffusion. Ideally, the sampling rate follows Fick's first law of diffusionwhere m is the mass flow rate, D is the diffusion coefficient of the chemical of interest, A is the area of the diffusion channels, 1 is the length of the diffusion channels, C, is the external (ambient) concentration of the chemical, and Co is the gas-phase concentration of the chemical at the surface of the collector or sorbent. Since PSDs require no pump or flow regulation system, they are considerably smaller, less costly, and less obtrustive than active sampling devices. Provided that the collected chemicals are tightly bound to the sorbent ( Co -0) , they may be left unattended for prolonged periods, since they do not depend on power sources. These characteristics make PSDs ideally suited not only for personal exposure monitoring but also for microenvironment applications and for use at remote sites where electrical power is unavailable.Most commercial devices use activated carbon as the collector; therefore, for most organic chemicals sorption is thermally irreversible in a practical sense and Co is essentially zero. Solvents such as carbon disulfide or a mixture of CS2 in methanol must be used to desorb the chemicals for analysis. Concentration by evaporation of the solvent extract is impractical for the analysis of volatile organic compounds. Consequently, carbon-based commercial dosimeters generally do not have adequate sensitivity for ambient (ppbv level) air Present address: University of Akron, Akron, OH 44325.

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