A new type of passive samplers were designed and produced by authors. After evaluating the quality of activated carbon by measuring recovery rate of organic vapors and steadiness of sampling rate, activated carbon with 30 - 35 mesh produced by Company S in Korea was selected. In each passive sampler, an amount of 400 ㎎ of the activated carbon was filled in 25-㎜ cassette and covered by fixed screen (or wire screen with 100 mesh). In addition to the fixed screen, a wind screen (or wire screen with 300 mesh) was also attached at outer face. The sampling rate of the new Korean passive samplers was estimated. Conclusions obtained in the study are as follows.
1 Sampling rates of the newly developed Korean passive samplers were affected by sampling time. For n-hexane, sampling rates of 15- and 60-minute samples were 70.92 and 37.45 ㎖/min, respectively. Sampling rate of both 200- and 450-minute samples was 25.96 ㎖/min. It is concluded that, when passive samplers are used for measuring organic vapors, samples be collected longer than 60 minutes.
2. Sampling rate of the passive samplers was also affected by airborne concentration of organic vapors. Lower sampling rates were determined at Level of 1/2 threshold limit values (TLVs) recommended by the American Conference of Governmental Industrial Hygienists (ACGIH). It is recommended that sampling rate of the passive samplers be obtained at site by measuring concentrations using both the NIOSH Method and passive samplers simultaneously.
3. When the passive samplers, which collected organic vapors, were exposed to clean air for five hours, there was no significant loss of organic vapors due to reverse diffusion.
4. When samples were stored at room temperature (21.8 ± 0.7℃) and refrigerator (3.8 0.7℃), there was no significant difference in the accuracy of results. For trichloroethylene and n-hexane, accuracies were within 25 % at both temperatures until seven days. However, poor accuracy exceeding 25 % was indicated in toluene from the first day. It is recommended that samples be stored at freezing temperature below 0 ℃.
5. Sampling efficiency was significantly affected by direction of the passive samplers. Results of samplers facing wind and down, respectively, were compared. Lower amount of organic vapors were collected when the sampler was oriented down. It is recommended that, when air velocity is low in plants, the passive samplers be oriented to the wind. However, when air velocity is high, the passive samplers be oriented down.
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