Characterization of Polymer-Coated Glass as a Passive Air Sampler for Persistent Organic Pollutants TOM HARNER,* ,† NICK J. FARRAR, ‡ MAHIBA SHOEIB, † KEVIN C. JONES, ‡ AND FRANK A. P. C. GOBAS § Meteorological Service of Canada, Environment Canada, 4905 Dufferin Street, Toronto, Ontario, Canada M3H 5T4, Environm ental Science Departm ent, Lancaster University, Lancaster, United Kingdom LA1 4YQ, and School of Resource and Environmental Management, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6 The use of thin-film polymer-coated glass surfaces or POGs as passive air samplers was investigated during an uptake experiment in an indoor environment with high levels of gas-phase polychlorinated biphenyls (PCBs). POGs consisted of a micron thick layer of ethylene vinyl acetate (EVA) coated onto glass cylinders. The uptake was initially linear with time and governed by the air-side mass transfer coefficient and surface area of the sampler. This was followed by a curvilinear region and finally a constant phase when equilibrium was established between air and EVA. The high surface area-to-volume ratio of the POGs allowed rapid equilibrium with gas-phase PCBs; equilibration times were on the order of hours for the low molecular weight congeners. The equilibrium concentration was dependent on the EVA-air partition coefficient, K EVA-A ,which was shown to be very well correlated to the octanol - air partition coefficient, K OA .When POGs of varying thickness were equilibrated with air, the amount of PCB accumulated increased with increasing thickness of the EVA, indicating that uptake was by absorption into the entire polymer matrix. A wind field of 4 m s -1 resulted in an increased uptake rate by a factor of approximately six compared to uptake in relatively still air. This wind speed effect was diminished, however, when POGs were housed in deployment chambers consisting of inverted stainless steel bowls. Relationships based on the air-side mass transfer coefficient and K EVA-A were developed for PCBs that describe the entire uptake profile and allow air concentrations to be determined from the amount of chemical accumulated in the POG. It is believed that these relationships are also valid when POGs are used to detect other classes of persistent organic pollutants. Introduction Research on persistent organic pollutants (POPs) would benefit from a simple approach for estimating air concen- trations. For the indoor environment, such data are useful for assessing exposure and evaluating risk. Kohler et al. (1) found alarmingly high ΣPCB levels in public buildings in Switzerland in the range 700-4000 ng m -3 ,2-3 orders of magnitude greaterthan typicaloutdoorconcentrations.They attributed this to construction materials such as sealants that may contain up to 30% PCB. Similar studies have investigated indoor concentrations of OCs (2), PAH (3,4), gaseous elemental mercury (5), and brominated flame retardants (6, 7). An increasing number of new chemicals are componentsofconventionalconstruction materialsand/ or are contained in common household products.Examples include brominated flame retardants(BFRs)which are added to foam materials (e.g. couch cushions, chairs and bed matresses) and electronics and fluorinated chemicals such as PFOS, that are applied to carpets and textiles for stain resistance. These typically “indoor” chemicals have been detected in the remote arctic where they have been shown to accumulate in the food chain (8, 9).Emissionsfrom indoor sources are suspected to be the dominant source to the outside . Aneed also exists for a simple approach to sample outdoor air in order to address uncertainties over the sources, long- range transport, and surface-air exchange of POPs. It would be beneficialto have an approach that enablessimultaneous samplingofairin different placesorrepeated samplingevents over time. Spatial mapping studies could be on a range of scales, from around a potential point source, across a city or region, or even nationally, regionally, or globally. The indoor and outdoor samplingneeds discussed above are usually not feasible with conventional hi-volume air samplers which are loud and intrusive, in the context of indoor sampling, and expensive and require power which limits their potential for outdoor studies. Hence, there is considerable incentive to develop passive air sampling techniques. Several interesting studies have made use of “environ- mental media”, such as leaves and pine needles (10-12), tree bark (13), soil (14, 15), and butter (16), where POPs concentrationsare believed to broadlyreflect ambient levels. However, there are often issues of sample comparability, exposure time, uptake kinetics, and potential confounding factors, which can produce uncertainties in data interpreta- tion It is envisaged that these problems can be excluded if passive samplerscan be designed and calibrated,which allow reliable estimates of air concentrations to be made. Several designsare possible and sindeed sare desirable.Forexample, it would be usefulto have samplers which integrate ambient concentrations over time scales as short as hours or as long as months/years. Shorter time scales facilitate studies of contaminant dispersal, fluxes, and transport processes and can provide data for dispersion/transport modeling. Longer time scales allow underlying trends in ambient levels to be investigated. To date, most work on passive samplers has focused on integrating concentrations over weeks/months. Outdoor studies have focused on samplers with a high “capacity”to retain POPs,such assemipermeable membrane devices (SPMDs) (17-22), polyurethane foam (PUFs) disks (23), and XAD resins (24). However, exciting possibilities are beingdeveloped forshort-term sampling.Forinstance,Koziel et al. (25) have used solid-phase microextraction (SPME) to sample formaldehyde in indoor air. It is also possible to operate on the principle that gas- phase POPs partition from the air onto samplers of “low capacity”, reaching equilibrium with the sampler. These *Correspondingauthor phone: (416)739-4837;fax: (416)739-5708; e-mail: tom.harner@ec.gc.ca. † Environment Canada. ‡ Lancaster University. § Simon Fraser University. Environ. Sci. Technol. 2003, 37, 2486-2493 2486 9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 37, NO. 11, 2003 10.1021/es0209215 CCC: $25.00  2003 American Chemical Society Published on Web 04/19/2003