Long-Term Evaluation of Mid-Cost Optical Particle Counters for PM2.5 Monitoring in an Underground Subway Station: Insights from a 15-Month Study
A beta-ray attenuation monitor (BAM) is preferred as a reference instrument for monitoring particulate matter in the air due to its accuracy. However, BAM cannot be used in large numbers for spatial distribution monitoring because of its high investment cost. Thus, a mid-cost optical particle counte...
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2025-01-01
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| author | Trieu-Vuong Dinh Byeong-Gyu Park Sang-Woo Lee In-Young Choi Da-Hyun Baek Jo-Chun Kim |
| author_facet | Trieu-Vuong Dinh Byeong-Gyu Park Sang-Woo Lee In-Young Choi Da-Hyun Baek Jo-Chun Kim |
| author_sort | Trieu-Vuong Dinh |
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| description | A beta-ray attenuation monitor (BAM) is preferred as a reference instrument for monitoring particulate matter in the air due to its accuracy. However, BAM cannot be used in large numbers for spatial distribution monitoring because of its high investment cost. Thus, a mid-cost optical particle counter (OPC) is an alternative solution for widespread use. However, its long-term performance with respect to various monitoring environments should be taken into account. In this study, six mid-cost OPCs were used to measure PM<sub>2.5</sub> concentrations at an underground subway station and compared with a reference BAM over 15 months. OPCs were placed in the waiting space and platforms to compare PM<sub>2.5</sub> concentrations and determine PM<sub>2.5</sub>/PM<sub>10</sub> ratios. The reference BAM was installed on the platform. Error analysis revealed a significant discrepancy, with normalized errors exceeding 30%, between the 1-h average PM<sub>2.5</sub> concentrations recorded by the BAM and OPCs at the same location. In contrast, the 24-h average PM<sub>2.5</sub> concentrations measured by the BAM and OPCs at the same location showed similar patterns, with stronger correlations (r<sup><span style="font-variant: small-caps;">2</span></sup> = 0.80–0.93) compared to the 1-h averages (r<sup><span style="font-variant: small-caps;">2</span></sup> = 0.63–0.83). The normalized errors for the 24-h averages ranged from 13.9% to 21.2%, depending on seasonal variations. These findings suggest that OPCs can effectively monitor 24-h average PM<sub>2.5</sub> concentrations in an underground subway station over a year without additional calibration, making them a cost-effective option. In addition, 1-h average PM<sub>2.5</sub> concentrations varied across different sampling spaces and were influenced by PM<sub>2.5</sub>/PM<sub>10</sub> ratios. Hence, when measuring the 1-h average mass concentration of PM<sub>2.5</sub>, it is essential to consider PM characteristics and seasons. |
| format | Article |
| id | doaj-art-5083c99edb864ad68a2dbe8fca4362a9 |
| institution | Kabale University |
| issn | 2227-9040 |
| language | English |
| publishDate | 2025-01-01 |
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| spelling | doaj-art-5083c99edb864ad68a2dbe8fca4362a92025-01-24T13:26:56ZengMDPI AGChemosensors2227-90402025-01-011312510.3390/chemosensors13010025Long-Term Evaluation of Mid-Cost Optical Particle Counters for PM2.5 Monitoring in an Underground Subway Station: Insights from a 15-Month StudyTrieu-Vuong Dinh0Byeong-Gyu Park1Sang-Woo Lee2In-Young Choi3Da-Hyun Baek4Jo-Chun Kim5International Climate and Environmental Research Center, Konkuk University, Seoul 05029, Republic of KoreaDepartment of Civil and Environmental Engineering, Konkuk University, Seoul 05029, Republic of KoreaDepartment of Civil and Environmental Engineering, Konkuk University, Seoul 05029, Republic of KoreaDepartment of Civil and Environmental Engineering, Konkuk University, Seoul 05029, Republic of KoreaDepartment of Civil and Environmental Engineering, Konkuk University, Seoul 05029, Republic of KoreaDepartment of Civil and Environmental Engineering, Konkuk University, Seoul 05029, Republic of KoreaA beta-ray attenuation monitor (BAM) is preferred as a reference instrument for monitoring particulate matter in the air due to its accuracy. However, BAM cannot be used in large numbers for spatial distribution monitoring because of its high investment cost. Thus, a mid-cost optical particle counter (OPC) is an alternative solution for widespread use. However, its long-term performance with respect to various monitoring environments should be taken into account. In this study, six mid-cost OPCs were used to measure PM<sub>2.5</sub> concentrations at an underground subway station and compared with a reference BAM over 15 months. OPCs were placed in the waiting space and platforms to compare PM<sub>2.5</sub> concentrations and determine PM<sub>2.5</sub>/PM<sub>10</sub> ratios. The reference BAM was installed on the platform. Error analysis revealed a significant discrepancy, with normalized errors exceeding 30%, between the 1-h average PM<sub>2.5</sub> concentrations recorded by the BAM and OPCs at the same location. In contrast, the 24-h average PM<sub>2.5</sub> concentrations measured by the BAM and OPCs at the same location showed similar patterns, with stronger correlations (r<sup><span style="font-variant: small-caps;">2</span></sup> = 0.80–0.93) compared to the 1-h averages (r<sup><span style="font-variant: small-caps;">2</span></sup> = 0.63–0.83). The normalized errors for the 24-h averages ranged from 13.9% to 21.2%, depending on seasonal variations. These findings suggest that OPCs can effectively monitor 24-h average PM<sub>2.5</sub> concentrations in an underground subway station over a year without additional calibration, making them a cost-effective option. In addition, 1-h average PM<sub>2.5</sub> concentrations varied across different sampling spaces and were influenced by PM<sub>2.5</sub>/PM<sub>10</sub> ratios. Hence, when measuring the 1-h average mass concentration of PM<sub>2.5</sub>, it is essential to consider PM characteristics and seasons.https://www.mdpi.com/2227-9040/13/1/25beta attenuation monitorfine particleslight scatteringmid-cost OPCsubway |
| spellingShingle | Trieu-Vuong Dinh Byeong-Gyu Park Sang-Woo Lee In-Young Choi Da-Hyun Baek Jo-Chun Kim Long-Term Evaluation of Mid-Cost Optical Particle Counters for PM2.5 Monitoring in an Underground Subway Station: Insights from a 15-Month Study Chemosensors beta attenuation monitor fine particles light scattering mid-cost OPC subway |
| title | Long-Term Evaluation of Mid-Cost Optical Particle Counters for PM2.5 Monitoring in an Underground Subway Station: Insights from a 15-Month Study |
| title_full | Long-Term Evaluation of Mid-Cost Optical Particle Counters for PM2.5 Monitoring in an Underground Subway Station: Insights from a 15-Month Study |
| title_fullStr | Long-Term Evaluation of Mid-Cost Optical Particle Counters for PM2.5 Monitoring in an Underground Subway Station: Insights from a 15-Month Study |
| title_full_unstemmed | Long-Term Evaluation of Mid-Cost Optical Particle Counters for PM2.5 Monitoring in an Underground Subway Station: Insights from a 15-Month Study |
| title_short | Long-Term Evaluation of Mid-Cost Optical Particle Counters for PM2.5 Monitoring in an Underground Subway Station: Insights from a 15-Month Study |
| title_sort | long term evaluation of mid cost optical particle counters for pm2 5 monitoring in an underground subway station insights from a 15 month study |
| topic | beta attenuation monitor fine particles light scattering mid-cost OPC subway |
| url | https://www.mdpi.com/2227-9040/13/1/25 |
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