Sung-Deuk Choi 1 , Song-Yee Baek 2 & Yoon-Seok Chang 2 1 School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), 100 Banyeon-ri, Eonyang-eup, Ulsan 689-805, Korea 2 School of Environmental Science and Engineering, Pohang University of Science and Technology (POSTECH), San 31 Hyoja-dong, Nam-gu, Pohang 790-784, Korea Correspondence and requests for materials should be addressed to S.-D. Choi (sdchoi@unist.ac.kr) Accepted 29 June 2009 Abstract Atmospheric monitoring is important for the investi- gation of source and receptor relationships of persis- tent organic pollutants (POPs). High volume samplers (HiVol), a kind of active air sampler, have been widely used to collect air samples containing POPs. Recent- ly, passive air samplers (PAS) have been developed, and they have several advantages compared with HiVol. In this paper, we introduced the principle, pro- perties, and applications of several types of PAS. Finally, the results of case studies from our group were presented. Since PAS have no electric pump and are much smaller and cheaper than HiVol, they can be used for various scaled monitoring studies. In Korea, we introduced three types of PAS: (1) semi- permeable membrane devices (SPMD), (2) polyure- thane foam (PUF), and (3) XAD resin-based PAS. The results of monitoring studies using these samplers suggest that PAS are a useful tool for the investigation on the level and distribution of POPs. Keywords: Passive air sampler, Persistent organic pollu- tants (POPs), Air pollution Introduction Persistent organic pollutants (POPs) are organic chemicals that are persistent in the environment, bio- accumulative through food chains, and endocrine dis- rupting or carcinogenic. They also undergo long-range atmospheric transport (LRAT) and even reach to polar regions 1 . In 2001, the United Nations Environment Program (UNEP) adopted the Stockholm convention for the global regulation of POPs, which went into ef- fect from 2004. The list of POPs under the Stockholm convention contains polychlorinated dibenzo-p-dioxin/ furans (PCDD/Fs), polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), and organochlorine pesti- cides (OCPs) 2 . As the major route of POPs dispersion and trans- port is the atmosphere, monitoring of POPs in the atmosphere is an essential step for the investigation on the fate of POPs in various environmental compart- ments. In a classical measurement of atmospheric POPs, active air samplers such as a high volume sam- pler (HiVol) have been used for the collection of POPs in both gaseous and particular phases. HiVol is a use- ful instrument to sample various POPs of ultra-trace levels in a short time period (usually 12-24 h). How- ever, it requires electricity and is a relatively heavy and expensive instrument. Moreover, glass fiber filters and polyurethane foams need to be changed everyday. Accordingly, it is hard to make a sampling network with high spatial resolution particularly at remote re- gions 3 . In recent years, various types of passive air samplers (PAS) for long-term POPs monitoring have been devel - oped 4-6 , and studies using PAS have become fairly abundant since the early 2000s 3 . PAS are much cheap- er and smaller (/50ſ50 cm, /1 kg) than convention- al active samplers, and they do not require electricity. For this reason, they can be used for environmental monitoring with a wide range of spatial coverage. In Korea, there have been limited studies using Pine needles as a natural passive sampler for POPs 7,8 . It was found that Pine needles could be an effective passive sampler representing the status of POPs pol- lution at local sites. Nevertheless, they lack reproduc- ibility; a comparison between different regions is doubtful because the properties of Pine needles at the different regions can be quite distinguishable in terms of needle ages and tree species. In 2004, we first intro- duced several types of PAS to Korea through joint researches with the University of Toronto and Envi- ronment Canada. With a build-up of analytical expe- rience, we have been conducting various passive air sampling studies. In this paper, we introduce the prin- Passive Air Sampling of Persistent Organic Pollutants in Korea Available online at www.ehs.or.kr