The Aerodynamic Aerosol Classifier (AAC) classifies particles with the desired aerodynamic diameter by generating opposing centrifugal and drag forces on the particles using rotating concentric cylinders and a clean sheath flow. Particle transmission through the classifier is described by its transfer function, which is an important indicator of classifier performance. Characterisation of the classifier’s transfer function improves the accuracy of its common aerosol applications, such as measuring particle size distributions or providing classified particles to other aerosol instruments for calibration or further analysis. This characterisation is commonly achieved experimentally using a tandem set-up of the same classifier. While this approach was previously used to characterise the AAC’s transfer function for particle aerodynamic diameters up to 2.4 µ m using a nebuliser and a Condensation Particle Counter (CPC), the current study expands the AAC’s characterisation up to 5 µ m using a condensation aerosol generator and an Optical Particle Counter (OPC). This upper size range is significantly higher than that offered by other common aerosol classifiers, such as the approximate 1 µ m upper limit typical of the Differential Mobility Analyser (DMA), and it is well suited to many applications, including OPC calibration, bio-aerosols, drug delivery and inhalation studies, and atmospheric dust analysis. This study found that the AAC maintains its high transmission efficiency ( ≥ 60%) for particles up to 5 µ m and that its transfer function width factor increases (i.e., the distribution becomes narrower) as the aerodynamic diameter increases. Setpoint agreement between two different production AACs remained within 2% over the size range tested. Therefore, the AAC has excellent performance for classifying particles up to 5 µ m.
{"title":"Characterisation of the Aerodynamic Aerosol Classifier Transfer Function for Particle Sizes up to 5 Micrometres","authors":"Simon D. Payne, T. Johnson, J. Symonds","doi":"10.4209/aaqr.230008","DOIUrl":"https://doi.org/10.4209/aaqr.230008","url":null,"abstract":"The Aerodynamic Aerosol Classifier (AAC) classifies particles with the desired aerodynamic diameter by generating opposing centrifugal and drag forces on the particles using rotating concentric cylinders and a clean sheath flow. Particle transmission through the classifier is described by its transfer function, which is an important indicator of classifier performance. Characterisation of the classifier’s transfer function improves the accuracy of its common aerosol applications, such as measuring particle size distributions or providing classified particles to other aerosol instruments for calibration or further analysis. This characterisation is commonly achieved experimentally using a tandem set-up of the same classifier. While this approach was previously used to characterise the AAC’s transfer function for particle aerodynamic diameters up to 2.4 µ m using a nebuliser and a Condensation Particle Counter (CPC), the current study expands the AAC’s characterisation up to 5 µ m using a condensation aerosol generator and an Optical Particle Counter (OPC). This upper size range is significantly higher than that offered by other common aerosol classifiers, such as the approximate 1 µ m upper limit typical of the Differential Mobility Analyser (DMA), and it is well suited to many applications, including OPC calibration, bio-aerosols, drug delivery and inhalation studies, and atmospheric dust analysis. This study found that the AAC maintains its high transmission efficiency ( ≥ 60%) for particles up to 5 µ m and that its transfer function width factor increases (i.e., the distribution becomes narrower) as the aerodynamic diameter increases. Setpoint agreement between two different production AACs remained within 2% over the size range tested. Therefore, the AAC has excellent performance for classifying particles up to 5 µ m.","PeriodicalId":7402,"journal":{"name":"Aerosol and Air Quality Research","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70296459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Siddharth Nobell, A. Majumdar, Shovon Mukherjee, Sukumar Chakraborty, Sanjoy Chatterjee, Soumitra Bose, Anindita Dutta, Sandhya Sethuraman, D. Westervelt, Shairik Sengupta, Rakhi Basu, V. McNeill
Low-cost sensors (LCS) provide opportunities for neighborhood-level air pollution data collection, yet significant knowledge gaps remain regarding the accurate application and interpretation of LCS. In this study, we present an in-field calibration of a network of 20 low-cost ambient particulate matter sensors (LCS) in greater Kolkata, India, operating between October 2018–April 2019. In order to understand LCS performance in relation to local reference-grade PM 2.5 monitors (RGMs), three of these LCS were co-located with RGMs operated by the West Bengal Pollution Control Board at Rabindra Bharati University (RBU), Victoria Memorial (VICTORIA), and Padmapukur (Howrah, PDM). Data from the co-locations were used to calibrate the LCS network using random forest regression and multiple linear regression approaches. Measured relative humidity and temperature were significant model features. Agreement between the LCS and RGM for 24-h averaged PM 2.5 measurements was strongest at RBU, with an uncalibrated root mean squared error (RMSE) of 27.1 µ g m –3 , followed by PDM (32.6 µ g m –3 ) and VICTORIA (50.7 µ g m –3 ). Multiple linear regression was used to derive calibration models. Cross-calibration between co-located LCS-RGM pairs was tested. The LCS data after cross-calibration correctly identified days as being in or out of attainment with the 24h National Ambient Air Quality Standard of 60 µ g m –3 91% of the time. The corrected data accurately identifies days with an India scale Air Quality Index of “poor” or worse 94% of the time. This suggests that LCS can be a useful supplement to RGM networks for air quality management. Diurnal trends and a high level of correlation across the hybrid LCS-RGM network suggest regional and secondary sources of PM 2.5 are important in Kolkata.
低成本传感器(LCS)为社区空气污染数据收集提供了机会，但在LCS的准确应用和解释方面仍存在重大知识空白。在本研究中，我们对2018年10月至2019年4月期间在印度大加尔各答运行的20个低成本环境颗粒物传感器(LCS)网络进行了现场校准。为了了解LCS与当地参考级pm2.5监测仪(RGMs)的关系，其中三个LCS与西孟加拉邦污染控制委员会在Rabindra Bharati大学(RBU)、维多利亚纪念堂(Victoria Memorial)和Padmapukur (Howrah, PDM)运营的RGMs一起安置。使用随机森林回归和多元线性回归方法，利用共址数据校准LCS网络。测量的相对湿度和温度是重要的模型特征。LCS和RGM在RBU的24小时平均pm2.5测量值之间的一致性最强，未经校准的均方根误差(RMSE)为27.1µg m -3，其次是PDM(32.6µg m -3)和VICTORIA(50.7µg m -3)。采用多元线性回归方法建立标定模型。对同址LCS-RGM对进行交叉校准检验。交叉校准后的LCS数据正确地识别出符合或不符合24小时国家环境空气质量标准60µg -3的天数占91%。修正后的数据准确地确定了94%的印度空气质量指数为“差”或更差的日子。这表明LCS可以作为RGM网络的有益补充，用于空气质量管理。混合LCS-RGM网络的日趋势和高度相关性表明，PM 2.5的区域和次要来源在加尔各答很重要。
{"title":"Validation of In-field Calibration for Low-Cost Sensors Measuring Ambient Particulate Matter in Kolkata, India","authors":"Siddharth Nobell, A. Majumdar, Shovon Mukherjee, Sukumar Chakraborty, Sanjoy Chatterjee, Soumitra Bose, Anindita Dutta, Sandhya Sethuraman, D. Westervelt, Shairik Sengupta, Rakhi Basu, V. McNeill","doi":"10.4209/aaqr.230010","DOIUrl":"https://doi.org/10.4209/aaqr.230010","url":null,"abstract":"Low-cost sensors (LCS) provide opportunities for neighborhood-level air pollution data collection, yet significant knowledge gaps remain regarding the accurate application and interpretation of LCS. In this study, we present an in-field calibration of a network of 20 low-cost ambient particulate matter sensors (LCS) in greater Kolkata, India, operating between October 2018–April 2019. In order to understand LCS performance in relation to local reference-grade PM 2.5 monitors (RGMs), three of these LCS were co-located with RGMs operated by the West Bengal Pollution Control Board at Rabindra Bharati University (RBU), Victoria Memorial (VICTORIA), and Padmapukur (Howrah, PDM). Data from the co-locations were used to calibrate the LCS network using random forest regression and multiple linear regression approaches. Measured relative humidity and temperature were significant model features. Agreement between the LCS and RGM for 24-h averaged PM 2.5 measurements was strongest at RBU, with an uncalibrated root mean squared error (RMSE) of 27.1 µ g m –3 , followed by PDM (32.6 µ g m –3 ) and VICTORIA (50.7 µ g m –3 ). Multiple linear regression was used to derive calibration models. Cross-calibration between co-located LCS-RGM pairs was tested. The LCS data after cross-calibration correctly identified days as being in or out of attainment with the 24h National Ambient Air Quality Standard of 60 µ g m –3 91% of the time. The corrected data accurately identifies days with an India scale Air Quality Index of “poor” or worse 94% of the time. This suggests that LCS can be a useful supplement to RGM networks for air quality management. Diurnal trends and a high level of correlation across the hybrid LCS-RGM network suggest regional and secondary sources of PM 2.5 are important in Kolkata.","PeriodicalId":7402,"journal":{"name":"Aerosol and Air Quality Research","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70296519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Vega, A. Wellens, A. L. Alarcón, R. Sosa, M. Solano, M. Jaimes-Palomera
A comprehensive analysis of the chemical composition of wet atmospheric deposition was performed on 7048 samples collected between 2003 and 2021 over Mexico City. The descending ion abundance trend was NH 4+ > SO 42– > NO 3– > Ca 2+ > Cl – > H + > Mg 2+ > Na + > K + , probably associated with industrial activity, heavy traffic and agricultural activities. Although main precursors have decreased importantly, ion composition did not show a clear trend throughout the years. Maximum concentrations of major ions were found in the northern and central part of the megacity, due to the impact of the Tula industrial corridor located north of the city. Weekly pH values varied from 3.6 to 9.4, being 27.1% of the values acidic. Fractional acidity showed that in sites located at higher altitudes, maximum 84.5% of the acidity was neutralized, whereas at northern stations at lower altitudes neutralization was observed up to 98%, due to the presence of alkaline species coming from the cement industry. Average ratios of (NH 4+ + Ca 2+ )/(NO 3– + SO 42– ) were > 1, suggesting neutralization of SO 42– and NO 3– by NH 4+ and Ca 2+ . Average NO 3– /SO 42– ratios suggested that the acidity was mainly influenced by sulfates coming from H 2 SO 4 . Wet deposition ranged from 4–9.9 kg ha –1 year –1 and from 8.2– 17.6 kg ha –1 year –1 for sulfur and nitrogen, respectively, among the geographical areas. The results of this study highlight the sensitivity of wet deposition chemistry to geographical, elevation and source considerations.
{"title":"Spatiotemporal Variations in Chemical Composition of Wet Atmospheric Deposition in Mexico City","authors":"E. Vega, A. Wellens, A. L. Alarcón, R. Sosa, M. Solano, M. Jaimes-Palomera","doi":"10.4209/aaqr.230023","DOIUrl":"https://doi.org/10.4209/aaqr.230023","url":null,"abstract":"A comprehensive analysis of the chemical composition of wet atmospheric deposition was performed on 7048 samples collected between 2003 and 2021 over Mexico City. The descending ion abundance trend was NH 4+ > SO 42– > NO 3– > Ca 2+ > Cl – > H + > Mg 2+ > Na + > K + , probably associated with industrial activity, heavy traffic and agricultural activities. Although main precursors have decreased importantly, ion composition did not show a clear trend throughout the years. Maximum concentrations of major ions were found in the northern and central part of the megacity, due to the impact of the Tula industrial corridor located north of the city. Weekly pH values varied from 3.6 to 9.4, being 27.1% of the values acidic. Fractional acidity showed that in sites located at higher altitudes, maximum 84.5% of the acidity was neutralized, whereas at northern stations at lower altitudes neutralization was observed up to 98%, due to the presence of alkaline species coming from the cement industry. Average ratios of (NH 4+ + Ca 2+ )/(NO 3– + SO 42– ) were > 1, suggesting neutralization of SO 42– and NO 3– by NH 4+ and Ca 2+ . Average NO 3– /SO 42– ratios suggested that the acidity was mainly influenced by sulfates coming from H 2 SO 4 . Wet deposition ranged from 4–9.9 kg ha –1 year –1 and from 8.2– 17.6 kg ha –1 year –1 for sulfur and nitrogen, respectively, among the geographical areas. The results of this study highlight the sensitivity of wet deposition chemistry to geographical, elevation and source considerations.","PeriodicalId":7402,"journal":{"name":"Aerosol and Air Quality Research","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70296714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. Sung, Hei-Tung Yip, Cheng-Li Lin, J. Jeng, Jiunn‐Tay Lee, Yu Sun, Cheng-Yu Wei, Po-Yen Yeh, Kuang-Hsi Chang, Shang-Yu Chien, K. Hsu, Tsr team
This study aimed to assess seasonal stroke risks related to temperature and PM 2.5 in Taiwan. Using data of the Taiwan Stroke Registry and air pollution monitored in 2006–2017, the researchers estimated daily average ischemic and hemorrhagic strokes according to temperature and PM 2.5 levels, evaluating stroke risks by categorizing PM 2.5 levels in each temperature zone. The results revealed a higher incidence of ischemic strokes in February and a higher incidence of hemorrhagic strokes in January, both decreased to the lowest in July. The study found that incident strokes increased with the PM 2.5 level in each temperature zone except for the 30+ ° C stratum. The highest incidence of ischemic strokes appeared at PM 2.5 greater than 37.0 µ g m –3 during 20–24 ° C, whereas the highest incidence of hemorrhagic strokes appeared at PM 2.5 greater than 37.0 µ g m –3 at less than 15 ° C. No adjusted RRs of strokes were significantly associated with PM 2.5 in all temperature zones after controlling for sex, age, BMI, smoking and drinking. We conclude that stroke incidence decreases as the weather gets warmer, whereas PM 2.5 pollution may have little effect on stroke incidence. It is essential to keep warm during cold days.
{"title":"Risk of Stroke Associated with Temperature and PM2.5: Taiwan Stroke Registry-based Study","authors":"F. Sung, Hei-Tung Yip, Cheng-Li Lin, J. Jeng, Jiunn‐Tay Lee, Yu Sun, Cheng-Yu Wei, Po-Yen Yeh, Kuang-Hsi Chang, Shang-Yu Chien, K. Hsu, Tsr team","doi":"10.4209/aaqr.230131","DOIUrl":"https://doi.org/10.4209/aaqr.230131","url":null,"abstract":"This study aimed to assess seasonal stroke risks related to temperature and PM 2.5 in Taiwan. Using data of the Taiwan Stroke Registry and air pollution monitored in 2006–2017, the researchers estimated daily average ischemic and hemorrhagic strokes according to temperature and PM 2.5 levels, evaluating stroke risks by categorizing PM 2.5 levels in each temperature zone. The results revealed a higher incidence of ischemic strokes in February and a higher incidence of hemorrhagic strokes in January, both decreased to the lowest in July. The study found that incident strokes increased with the PM 2.5 level in each temperature zone except for the 30+ ° C stratum. The highest incidence of ischemic strokes appeared at PM 2.5 greater than 37.0 µ g m –3 during 20–24 ° C, whereas the highest incidence of hemorrhagic strokes appeared at PM 2.5 greater than 37.0 µ g m –3 at less than 15 ° C. No adjusted RRs of strokes were significantly associated with PM 2.5 in all temperature zones after controlling for sex, age, BMI, smoking and drinking. We conclude that stroke incidence decreases as the weather gets warmer, whereas PM 2.5 pollution may have little effect on stroke incidence. It is essential to keep warm during cold days.","PeriodicalId":7402,"journal":{"name":"Aerosol and Air Quality Research","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70297746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C.Y. Suen, Helen H.L. Kwok, Y.H. Tsui, K.H. Lui, H.H. Leung, K.W. Lam, K.P.S. Hung, Joseph K.C. Kwan, K.F. Ho
An experiment coupled with a computational analysis was conducted to investigate the effectiveness of surgical masks, which include KF94 and ASTM Level 1, in an indoor environment. The KF94 mask sample shows the highest filtration efficiency (99.9%) in the analysis. The simulation is consistent with the experimental results as the concentration of sodium chloride (NaCl) droplets is < 4% on average in the room. The ultraviolet-C (UVC) irradiation and dry heating samples are shown to retain the highest filtration efficiencies (> 97%) after 3 disinfection treatment cycles. All methods (boiling, steaming, ethanol treatment, and dry heating) effectively reduce the S. aureus load by 99.99%. The UVC irradiation shows exposure to 450 µW cm-2 for 10 minutes can effectively eliminate all S. aureus on the mask materials. Simulation shows the reduction in overall NaCl and carbon dioxide (CO2) levels is directly proportional to the filtration efficiency and the effectiveness of reused masks is also directly proportional to the filtration efficiency. The proxy indicator (CO2) for aerosol particles demonstrates that very fine respiratory droplets can penetrate the mask after reaching a steady state. The CO2 concentration increase shows that aerosol particles are accumulated under adequate ventilation and further pose the risk of infection. The NaCl droplets (2%) simulation shows that respiratory droplets have infiltrated the mask, but the mask demonstrates a higher ability to block the NaCl droplets and prevent their penetration. The findings suggest a need to revise the existing regulation of the control policy.
通过实验结合计算分析，研究了KF94和ASTM 1级医用口罩在室内环境中的有效性。KF94掩膜样品的过滤效率最高(99.9%)。室内氯化钠(NaCl)液滴浓度平均< 4%，模拟结果与实验结果一致。紫外- c (UVC)辐照和干热样品在3个消毒处理循环后保持最高的过滤效率(> 97%)。所有方法(煮沸、蒸煮、乙醇处理和干热)均可有效减少金黄色葡萄球菌负荷99.99%。紫外辐射显示，在450µW cm-2下照射10分钟，可以有效去除口罩材料上的所有金黄色葡萄球菌。模拟结果表明，总体NaCl和CO2水平的降低与过滤效率成正比，重复使用面罩的有效性也与过滤效率成正比。气溶胶颗粒的替代指标(CO2)表明，非常细的呼吸道飞沫在达到稳定状态后可以穿透面罩。二氧化碳浓度的增加表明，气溶胶颗粒在充分通风的情况下积聚，并进一步构成感染的风险。NaCl液滴(2%)模拟表明，呼吸液滴已经渗透到面罩中，但面罩对NaCl液滴的阻挡和阻止能力更强。调查结果表明，有必要修订现有的控制政策条例。
{"title":"Experimental and Computational Analysis of Surgical Mask Effectiveness Against COVID-19 in Indoor Environment","authors":"C.Y. Suen, Helen H.L. Kwok, Y.H. Tsui, K.H. Lui, H.H. Leung, K.W. Lam, K.P.S. Hung, Joseph K.C. Kwan, K.F. Ho","doi":"10.4209/aaqr.230123","DOIUrl":"https://doi.org/10.4209/aaqr.230123","url":null,"abstract":"An experiment coupled with a computational analysis was conducted to investigate the effectiveness of surgical masks, which include KF94 and ASTM Level 1, in an indoor environment. The KF94 mask sample shows the highest filtration efficiency (99.9%) in the analysis. The simulation is consistent with the experimental results as the concentration of sodium chloride (NaCl) droplets is < 4% on average in the room. The ultraviolet-C (UVC) irradiation and dry heating samples are shown to retain the highest filtration efficiencies (> 97%) after 3 disinfection treatment cycles. All methods (boiling, steaming, ethanol treatment, and dry heating) effectively reduce the S. aureus load by 99.99%. The UVC irradiation shows exposure to 450 µW cm-2 for 10 minutes can effectively eliminate all S. aureus on the mask materials. Simulation shows the reduction in overall NaCl and carbon dioxide (CO2) levels is directly proportional to the filtration efficiency and the effectiveness of reused masks is also directly proportional to the filtration efficiency. The proxy indicator (CO2) for aerosol particles demonstrates that very fine respiratory droplets can penetrate the mask after reaching a steady state. The CO2 concentration increase shows that aerosol particles are accumulated under adequate ventilation and further pose the risk of infection. The NaCl droplets (2%) simulation shows that respiratory droplets have infiltrated the mask, but the mask demonstrates a higher ability to block the NaCl droplets and prevent their penetration. The findings suggest a need to revise the existing regulation of the control policy.","PeriodicalId":7402,"journal":{"name":"Aerosol and Air Quality Research","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136217597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yongjoo Choi, Y. Kanaya, H. Takashima, Kihong Park, Haebum Lee, J. Chong, Jae Hwan Kim, Jin-Soo Park
We investigated the impact of human activity during COVID-19 on the tropospheric nitrogen dioxide vertical column density (NO2 TropVCD) at three urban sites (Gwangju and Busan in Korea and Yokosuka in Japan) and one remote site (Cape Hedo in Japan) from Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) and Pandora. Compared to the monthly mean NO2 TropVCD from 2015 to 2018 and in 2019, the values were lower in 2020 due to social distancing in Korea and Japan. High negative relative changes were observed from May to September (-30% to -18%) at the three urban sites;Cape Hedo, a remote site, did not show a significant difference in relative changes between previous years and 2020, suggesting that only anthropogenic emission sources decreased dramatically. In the case of Yokosuka, the 15-day moving average of the NO2 TropVCD exhibited a good relationship with transportation (R = 0.48) and industry (R = 0.54) mobility data. In contrast, the NO2 TropVCD at the Korean sites showed a moderate to low correlation with the industrial sector and insignificant correlations with transportation. The differences in correlations might be caused by the different social distancing policies in Korea (voluntary) and Japan (mandatory). By applying generalized boosted models to exclude meteorological and seasonal effects associated with NO2 TropVCD variations, we revealed that the decreasing trend from 2019 to 2020 was much steeper than that from 2015 to 2020 (a factor of two), and a significant change was identified in January 2020, when the first cases of COVID-19 were observed in both Korea and Japan. This result confirmed that the reduction in NO2 can be largely explained by the NOx emission reduction resulting from social distancing for COVID-19 rather than annual meteorological differences;however, in December 2020, NO2 recovered suddenly to its previous level due to an increase in human activities.
{"title":"Changes in Tropospheric Nitrogen Dioxide Vertical Column Densities over Japan and Korea during the COVID-19 Using Pandora and MAX-DOAS","authors":"Yongjoo Choi, Y. Kanaya, H. Takashima, Kihong Park, Haebum Lee, J. Chong, Jae Hwan Kim, Jin-Soo Park","doi":"10.4209/aaqr.220145","DOIUrl":"https://doi.org/10.4209/aaqr.220145","url":null,"abstract":"We investigated the impact of human activity during COVID-19 on the tropospheric nitrogen dioxide vertical column density (NO2 TropVCD) at three urban sites (Gwangju and Busan in Korea and Yokosuka in Japan) and one remote site (Cape Hedo in Japan) from Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) and Pandora. Compared to the monthly mean NO2 TropVCD from 2015 to 2018 and in 2019, the values were lower in 2020 due to social distancing in Korea and Japan. High negative relative changes were observed from May to September (-30% to -18%) at the three urban sites;Cape Hedo, a remote site, did not show a significant difference in relative changes between previous years and 2020, suggesting that only anthropogenic emission sources decreased dramatically. In the case of Yokosuka, the 15-day moving average of the NO2 TropVCD exhibited a good relationship with transportation (R = 0.48) and industry (R = 0.54) mobility data. In contrast, the NO2 TropVCD at the Korean sites showed a moderate to low correlation with the industrial sector and insignificant correlations with transportation. The differences in correlations might be caused by the different social distancing policies in Korea (voluntary) and Japan (mandatory). By applying generalized boosted models to exclude meteorological and seasonal effects associated with NO2 TropVCD variations, we revealed that the decreasing trend from 2019 to 2020 was much steeper than that from 2015 to 2020 (a factor of two), and a significant change was identified in January 2020, when the first cases of COVID-19 were observed in both Korea and Japan. This result confirmed that the reduction in NO2 can be largely explained by the NOx emission reduction resulting from social distancing for COVID-19 rather than annual meteorological differences;however, in December 2020, NO2 recovered suddenly to its previous level due to an increase in human activities.","PeriodicalId":7402,"journal":{"name":"Aerosol and Air Quality Research","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70292615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wenting Liu, Bowen Zhao, Qian Feng, Zhiyong Zhou, Jia Lu
At present, filterable particulate matter (FPM) emissions from stable source flue gases are well controlled, and the more difficult to remove condensable particulate matter (CPM) has received much attention due to its environmental hazards. In this study, we built a cold electrode electrostatic precipitator (CE-ESP) and systematically investigated the removal efficiency of CPM from municipal solid waste incineration plant flue gas by CE-ESP under three different operating modes. The results showed that hydrocarbons, esters and aromatic compounds were the main organic substances in CPM. The CE-ESP had a significant contribution to the removal of SO 42– , F – , Al, Ni, Cr, and Pb from CPM. In contrast, it had a less effective removal of NO 3– and Ca in CPM. The CE-ESP was effective for removing esters in CPM. The removal efficiency of CE-ESP for CPM could reach 76%, and the removal efficiency of organic substance was higher than that of inorganic substance. It is demonstrated that the combination of thermophoretic force and electric field in CE-ESP intensifies the turbulent agglomeration process, and the diffusion force generated by the concentration field synergistically enhances the interparticle coagulation and agglomeration. This promotes the homogeneous condensation process of CPM and the heterogeneous condensation of CPM and FPM, which is conducive to the reduction of condensable particulate matter in flue gas and can provide a theoretical basis for practical application in engineering
{"title":"Synergistic Effect of Multi-field Force on Condensable Particulate Matter Properties and Behavior in Flue Gas: A Case Study in a Municipal Solid Waste Incineration Plan","authors":"Wenting Liu, Bowen Zhao, Qian Feng, Zhiyong Zhou, Jia Lu","doi":"10.4209/aaqr.220217","DOIUrl":"https://doi.org/10.4209/aaqr.220217","url":null,"abstract":"At present, filterable particulate matter (FPM) emissions from stable source flue gases are well controlled, and the more difficult to remove condensable particulate matter (CPM) has received much attention due to its environmental hazards. In this study, we built a cold electrode electrostatic precipitator (CE-ESP) and systematically investigated the removal efficiency of CPM from municipal solid waste incineration plant flue gas by CE-ESP under three different operating modes. The results showed that hydrocarbons, esters and aromatic compounds were the main organic substances in CPM. The CE-ESP had a significant contribution to the removal of SO 42– , F – , Al, Ni, Cr, and Pb from CPM. In contrast, it had a less effective removal of NO 3– and Ca in CPM. The CE-ESP was effective for removing esters in CPM. The removal efficiency of CE-ESP for CPM could reach 76%, and the removal efficiency of organic substance was higher than that of inorganic substance. It is demonstrated that the combination of thermophoretic force and electric field in CE-ESP intensifies the turbulent agglomeration process, and the diffusion force generated by the concentration field synergistically enhances the interparticle coagulation and agglomeration. This promotes the homogeneous condensation process of CPM and the heterogeneous condensation of CPM and FPM, which is conducive to the reduction of condensable particulate matter in flue gas and can provide a theoretical basis for practical application in engineering","PeriodicalId":7402,"journal":{"name":"Aerosol and Air Quality Research","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70293582","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Young-Su Jeong, H. Seo, Sangil Han, Young-jin Koh, Kibong Choi
Biological warfare agents (BWAs) cause disease in humans, animals, and plants when purposefully dispersed in an area. To minimize contamination and personnel exposure and initiate early treatment, effective BWA detection or monitoring techniques are needed. Currently, bioaerosol detection or monitoring techniques are used for detecting BWA; however, these techniques have limitations, such as limited sensitivity. To improve the detection performance and develop novel techniques, an additional step in sample preparation, such as obtaining particles of various sizes, is needed. In this study, we investigated the simple and effective generation of bioaerosol particles using a custom-made inkjet aerosol generator (IJAG). Unlike previous inkjet aerosol generators, the operation conditions of the IJAG are fixed at a nozzle heating temperature of 140 ° C, a driver voltage of 150 V, a pulse width of 60 µ s, and a frequency of 250 Hz. The only controlled factor was the concentration of bioaerosol models, including Bacillus globigii spores, ovalbumin, and polystyrene sphere latex. Our system generated bioaerosols with a diameter of 1–8 µ m and a narrow distribution size. These results suggest that our IJAG system can achieve the simple and versatile generation of narrow-dispersed bioaerosols for a wide range of available materials. Our study can help improve the sensitivity of detection and monitoring systems for BWAs and bioaerosols.
{"title":"A Simple Method for Generating Narrowly-dispersed Bioaerosols in Various Sizes","authors":"Young-Su Jeong, H. Seo, Sangil Han, Young-jin Koh, Kibong Choi","doi":"10.4209/aaqr.220218","DOIUrl":"https://doi.org/10.4209/aaqr.220218","url":null,"abstract":"Biological warfare agents (BWAs) cause disease in humans, animals, and plants when purposefully dispersed in an area. To minimize contamination and personnel exposure and initiate early treatment, effective BWA detection or monitoring techniques are needed. Currently, bioaerosol detection or monitoring techniques are used for detecting BWA; however, these techniques have limitations, such as limited sensitivity. To improve the detection performance and develop novel techniques, an additional step in sample preparation, such as obtaining particles of various sizes, is needed. In this study, we investigated the simple and effective generation of bioaerosol particles using a custom-made inkjet aerosol generator (IJAG). Unlike previous inkjet aerosol generators, the operation conditions of the IJAG are fixed at a nozzle heating temperature of 140 ° C, a driver voltage of 150 V, a pulse width of 60 µ s, and a frequency of 250 Hz. The only controlled factor was the concentration of bioaerosol models, including Bacillus globigii spores, ovalbumin, and polystyrene sphere latex. Our system generated bioaerosols with a diameter of 1–8 µ m and a narrow distribution size. These results suggest that our IJAG system can achieve the simple and versatile generation of narrow-dispersed bioaerosols for a wide range of available materials. Our study can help improve the sensitivity of detection and monitoring systems for BWAs and bioaerosols.","PeriodicalId":7402,"journal":{"name":"Aerosol and Air Quality Research","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70293621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Pushpawela, S. Shelton, G. Liyanage, Sanduni Jayasekara, Dimuthu Rajapaksha, Akila Jayasundara, Lesty Das Jayasuriya
In response to the COVID-19 pandemic in early 2020, Sri Lanka underwent a nationwide lockdown that limited motor vehicle movement, industrial operations, and human activities. This study analyzes the impact of COVID-19 lockdown on carbon monoxide (CO), ozone (O 3 ), nitrogen dioxide (NO 2 ), sulfur dioxide (SO 2 ), and particulate matter (PM 10 , PM 2.5 ) concentrations in two urban cities (Colombo and Kandy) in Sri Lanka, by comparison of data from the lockdown period (March to May 2020) with its analogous period of 2019 and 2021. The results showed that the percentage change of daytime PM 10 , PM 2.5 , CO, and NO 2 concentration during the lockdown in Colombo (Kandy) is –42.3% (–39.5%), –46% (–54.2%), –14.7% (–8.8%) and –82.2% (–80.9%), respectively. In both cities, the response of NO 2 to the lockdown was the most sensitive. In contrast, daytime O 3 concentration in Colombo (Kandy) has increased by 6.7% (27.2%), suggesting that the increase in O 3 concentration was mainly due to a reduction in NO x emissions leading to lower O 3 titration by NO. In addition, daytime SO 2 concentration in Colombo has increased by 22.9%, while daytime SO 2 concentration in Kandy has decreased by –40%. During the lockdown period, human activities were significantly reduced, causing significant reductions in industrial operations and transportation activities, further reducing emissions and improving air quality in two cities. The results of this study offer potential for local authorities to better understand the emission sources, assess the effectiveness of current air pollution control strategies, and form a basis for formulating better environmental policies to improve air quality and human health.
{"title":"Changes of Air Pollutants in Urban Cities during the COVID-19 Lockdown-Sri Lanka","authors":"B. Pushpawela, S. Shelton, G. Liyanage, Sanduni Jayasekara, Dimuthu Rajapaksha, Akila Jayasundara, Lesty Das Jayasuriya","doi":"10.4209/aaqr.220223","DOIUrl":"https://doi.org/10.4209/aaqr.220223","url":null,"abstract":"In response to the COVID-19 pandemic in early 2020, Sri Lanka underwent a nationwide lockdown that limited motor vehicle movement, industrial operations, and human activities. This study analyzes the impact of COVID-19 lockdown on carbon monoxide (CO), ozone (O 3 ), nitrogen dioxide (NO 2 ), sulfur dioxide (SO 2 ), and particulate matter (PM 10 , PM 2.5 ) concentrations in two urban cities (Colombo and Kandy) in Sri Lanka, by comparison of data from the lockdown period (March to May 2020) with its analogous period of 2019 and 2021. The results showed that the percentage change of daytime PM 10 , PM 2.5 , CO, and NO 2 concentration during the lockdown in Colombo (Kandy) is –42.3% (–39.5%), –46% (–54.2%), –14.7% (–8.8%) and –82.2% (–80.9%), respectively. In both cities, the response of NO 2 to the lockdown was the most sensitive. In contrast, daytime O 3 concentration in Colombo (Kandy) has increased by 6.7% (27.2%), suggesting that the increase in O 3 concentration was mainly due to a reduction in NO x emissions leading to lower O 3 titration by NO. In addition, daytime SO 2 concentration in Colombo has increased by 22.9%, while daytime SO 2 concentration in Kandy has decreased by –40%. During the lockdown period, human activities were significantly reduced, causing significant reductions in industrial operations and transportation activities, further reducing emissions and improving air quality in two cities. The results of this study offer potential for local authorities to better understand the emission sources, assess the effectiveness of current air pollution control strategies, and form a basis for formulating better environmental policies to improve air quality and human health.","PeriodicalId":7402,"journal":{"name":"Aerosol and Air Quality Research","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70293709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yang Cao, Xiaoli Zhao, Debin Su, Xiang Cheng, Hong Ren
Ozone pollution is harmful to human health and ecosystem, which occurs in ecosystems and has occurred frequently in China in recent years, especially during the warm seasons. Meteorological conditions are among the important factors affecting the occurrence of ozone pollution. In this study, a classification method for meteorological conditions of ozone pollution levels based on a back propagation (BP) neural network was proposed to reflect the impact of meteorological conditions on the occurrence of ozone pollution. Ozone pollution was divided into three levels according to surface hourly ozone (O 3 ) concentrations and thus into three groups of meteorological conditions. The input physical parameters for the BP neural network were determined by evaluating the relationship between surface O 3 concentrations and meteorological parameters and precursors, including relative humidity, temperature, mixing layer height, precipitation
摘要
{"title":"A Machine-Learning-Based Classification Method for Meteorological Conditions of Ozone Pollution","authors":"Yang Cao, Xiaoli Zhao, Debin Su, Xiang Cheng, Hong Ren","doi":"10.4209/aaqr.220239","DOIUrl":"https://doi.org/10.4209/aaqr.220239","url":null,"abstract":"Ozone pollution is harmful to human health and ecosystem, which occurs in ecosystems and has occurred frequently in China in recent years, especially during the warm seasons. Meteorological conditions are among the important factors affecting the occurrence of ozone pollution. In this study, a classification method for meteorological conditions of ozone pollution levels based on a back propagation (BP) neural network was proposed to reflect the impact of meteorological conditions on the occurrence of ozone pollution. Ozone pollution was divided into three levels according to surface hourly ozone (O 3 ) concentrations and thus into three groups of meteorological conditions. The input physical parameters for the BP neural network were determined by evaluating the relationship between surface O 3 concentrations and meteorological parameters and precursors, including relative humidity, temperature, mixing layer height, precipitation","PeriodicalId":7402,"journal":{"name":"Aerosol and Air Quality Research","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70293836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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