scholarly journals Performance Evaluation of the Novel Portable PIMA Point-Of-Care CD4 Analyzer in Comparison with Conventional Flow Cytometer Instruments in Cameroon

2020 ◽  
Author(s):  
Bertrand Sagnia ◽  
Rachel Kamgaing ◽  
Charles Kouanfack ◽  
Georgette Kamdem ◽  
Samuel Sosso ◽  
...  

Abstract Background: Absolute CD4 + T-lymphocyte counts are used in the initiation and monitoring of antiretroviral therapy in HIV-infected patients: with the increase number of HIV infected patient and the reduce number of heath care system in rural zones, HIV monitoring in resource-constrained settings demands affordable and reliable CD4 + T lymphocytes enumeration methods. We evaluated a simple PIMA POC which is a dedicated system for enumeration that uses immunomagnetic and immunofluorescent technologies. The instrument was designed to be a low-cost, yet reliable and robust one. In this study, we assessed the correlation between most representative flow cytometry instruments present in Cameroon instead of CyFlow from PARTEC, FACSCount, and FACSCalibur both from Becton DickinsonMethods: CD4 surface markers on lymphocytes was measured on samples collected in EDTA tubes from 268 patients aged from 1 to 65 years old in three different health care structures. HIV infected patients are coming from CIRCB, Day Hospital of Hopital Central de Yaounde (HCY) and Hopital General de Yaounde (HGY). After inform consent, samples were collected and 101 samples were tested with the FACSCalibur, 60 samples were tested with the CyFlow and 107 samples were tested with the FACSCount flow cytometers. All these samples were tested by different technician with PIMA POC present in all these health care structures and the correlation and agreement were analyzed using linear regression and Bland–Altman analysis.Results: The PIMA POC system has excellent precision, accuracy and linearity for CD4 + T lymphocytes enumeration. Good correlations were obtained between the PIMA POC system and other single platform methods. Bland–Altman plots showed interchangeability between the three machines. Absolute CD4 + T-lymphocyte values obtained from the PIMA system correlated well with Cyflow, FACSCount, and FACSCalibur method (r2 varies from 0.88 to 0.968, P < 0.0001). The comparison between values obtained from PIMA with CYFLOW, FACSCount, and FACSCalibur give P = 0.17, P = 0.5 and P = 0.6 respectively meaning that there is not significant differences between values obtained with PIMA and other flow machines.Conclusion: This POC PIMA system is a simple and reliable system for enumeration of absolute CD4 + T-lymphocytes. Having one PIMA system easy to use, should reduce the cost and thus increase access to CD4 testing for HIV infected patients in resource-constrained countries. POC CD4 may also alleviate testing burdens at traditional central CD4 laboratories, hence improving test access in both rural and urban environments. This will reduce also the loss of follow up

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Bertrand Sagnia ◽  
Rachel Kamgaing ◽  
Charles Kouanfack ◽  
Georgette Kamdem ◽  
Samuel Sosso ◽  
...  

Abstract Background Absolute CD4+ T-lymphocyte counts are used in the initiation and monitoring of antiretroviral therapy in HIV-infected patients: with the increase number of HIV infected patient and the reduce number of heath care system in rural zones, HIV monitoring in resource-constrained settings demands affordable and reliable CD4+ T lymphocytes enumeration methods. We evaluated a simple PIMA POC which is a dedicated system for enumeration that uses immunomagnetic and immunofluorescent technologies. The instrument was designed to be a low-cost, yet reliable and robust one. In this study, we assessed the correlation between most representative flow cytometry instruments present in Cameroon instead of CyFlow from PARTEC, FACSCount, and FACSCalibur both from Becton Dickinson. Methods CD4 surface markers on lymphocytes was measured on samples collected in EDTA tubes from 268 patients aged from 1 to 65 years old in three different health care structures. HIV infected patients are coming from CIRCB, Day Hospital of Hopital Central de Yaounde (HCY) and Hopital General de Yaounde (HGY). After inform consent, samples were collected and 101 samples were tested with the FACSCalibur, 60 samples were tested with the CyFlow and 107 samples were tested with the FACSCount flow cytometers. All these samples were tested by different technician with PIMA POC present in all these health care structures and the correlation and agreement were analyzed using linear regression and Bland–Altman analysis. Results The PIMA POC system has excellent precision, accuracy and linearity for CD4+ T lymphocytes enumeration. Good correlations were obtained between the PIMA POC system and other single platform methods. Bland–Altman plots showed interchangeability between the three machines. Absolute CD4+ T-lymphocyte values obtained from the PIMA system correlated well with Cyflow, FACSCount, and FACSCalibur method (r2 varies from 0.88 to 0.968, P < 0.0001). The comparison between values obtained from PIMA with CYFLOW, FACSCount, and FACSCalibur give P = 0.17, P = 0.5 and P = 0.6 respectively meaning that there is not significant differences between values obtained with PIMA and other flow machines. Conclusion This POC PIMA system is a simple and reliable system for enumeration of absolute CD4+ T-lymphocytes. Having one PIMA system easy to use, should reduce the cost and thus increase access to CD4 testing for HIV infected patients in resource-constrained countries. POC CD4 may also alleviate testing burdens at traditional central CD4 laboratories, hence improving test access in both rural and urban environments. This will reduce also the loss of follow up.


2020 ◽  
Author(s):  
Bertrand Sagnia ◽  
Fabrice MBAKOP Ghomsi ◽  
Ana Gutierrez ◽  
Samuel SOSSO ◽  
Rachel KAMGAING ◽  
...  

Abstract Background In the context of scaling the viral load in resource limited settings, following HIV infected patient’s adults and children with CD4+ T-lymphocyte count still very important in settings where the decentralization of treatment still has some challenges. Effective HIV monitoring in these resource-constrained settings needs affordable and reliable CD4+ T lymphocytes enumeration methods. We investigated the validity of a BD FACSPresto POC which is a dedicated system for enumeration that uses immunofluorescent technologies. In this study, we have assessed the sensitivity, specificity and correlation between most representative flow cytometry instruments present in Cameroon with more than 5000 CD4 T cells tests per year including FACSCalibur, FACSCount, and PIMA POC from Becton dinkinson and ALERE respectively. Methods 268 patients aged from 1 to 72 years old were enrolled and included in the study after inform consent. The BD FACSPresto POC CD4+ T cell technology was placed at CIRCB and operated by technician staff. HIV infected patients were from Chantal BIYA international reference Center (CIRCB), Centre de Sante Catholique de NKOLODOM, Centre de Sante Catholique de BIKOP and CASS de Nkolndongo – Yaounde We compared the accuracy of the BD FACSPresto and three existing reference technologies with more than 5000 tests per year like FACSCalibur, FACSCount and PIMA according to the number of CD4 test done per year and their repartition in the country. Bland – Altman method and correlation analysis were used to estimate mean bias and 95% limits of agreement and to compare the methods, including analysis by subgroup of participant gestational age. In addition sensitivity and specificity were determined. Statistical significance was set at p-value < 0.05 Results The BD FACSPresto POC system has excellent precision, accuracy and linearity for CD4+ T lymphocytes enumeration. Good correlations were obtained between the BD FACSPresto poc system and other single platform methods. Bland–Altman plots showed interchangeability between two machines mean bias BD-FACSPresto vs PIMA= -126,522(-161,221 to -91,822) BD-FACSPresto vs FACSCount= -38,708 (-58,935 to -18,482) and FACSPresto vs FACSCALIBUR= 0,791(-11,908 to 13,491). Mean difference with Absolute CD4+ T-lymphocyte values obtained from the BD FACSPresto system correlated well with PIMA, FACSCount, and FACSCalibur method with R 2 equal to 0.88, 0.92 and 0.968 respectively with P < 0.001 for all. The mean comparison between values obtained from BD FACSPresto with PIMA, FACSCount, and FACSCalibur using paired T test give P=0.17, P=0.5 and P=0.6 respectively meaning that there is no significant differences between values obtained with BD FACSPresto and PIMA, FACSCount or FACSCalibur CD4 enumeration machines. Further analysis revealed close agreement between all the three instruments with no significant difference between the forth methods (P=0.91) Conclusion This BD-FACSPresto POC system is a simple, robust and reliable system for enumeration of absolute and percentage of CD4+ T-lymphocytes especially suitable for remote areas with limited resources. Having one BD-FACSPresto POC system easy to use, should reduce the cost and thus increase and improved access to CD4 testing for HIV infected patients in resource-constrained countries. BD-FACSPresto POC CD4 will enable reduction in patient time and improve the overall quality of ART service count and may improve test access in remote areas. This technology can allow for greater decentralization and wider access to CD4 testing and ART


2020 ◽  
Author(s):  
Bertrand Sagnia ◽  
Fabrice MBAKOP Ghomsi ◽  
Ana Gutierrez ◽  
Samuel SOSSO ◽  
Rachel KAMGAING ◽  
...  

Abstract Background In view of scaling up viral load during the management of HIV in adults and children in resource limited settings, CD4+ T-lymphocyte count still relevant in remote areas where the decentralization of treatment is independent of viral load. Effective clinical management of HIV within these resource-constrained settings depends on affordable and reliable CD4+ T lymphocytes enumeration methods. We have assessed the performance of a BD FACSPresto POC which is a dedicated CD4 enumeration system applicable in remote areas. A comparative analysis was made between the performance of the BD FACSPresto POC and representative flow cytometry instruments present in Cameroon in including FACSCalibur, FACSCount, and PIMA POC from Becton Dickinson and ALERE respectively. All these CD4 enumerations are known to perform more than 5000 CD4 T cells tests per year. Methods: The BD FACSPresto POC CD4+ T cell technology was placed at CIRCB and operated by technician staff. 268 patients aged between 1 to 72 years old were included in the study. Participants were recruited from the Chantal BIYA international reference Center (CIRCB), Centre de Sante Catholique de NKOLODOM, Centre de Sante Catholique de BIKOP and CASS de Nkolndongo – Yaounde respectively. We compared the performance of the BD FACSPresto with three existing CD4 enumeration technologies including FACSCalibur, FACSCount and PIMA capable of performing more than 5000 tests per year. Bland – Altman method and correlation analysis were used to estimate mean bias and 95% limits of agreement and to compare the methods, including analysis by subgroup of participant gestational age. Statistical significance was set at p-value < 0.05 Results: The BD FACSPresto POC CD4 enumeration system showed similar performance with the other CD4+ T lymphocytes enumeration instruments. Strong correlations were obtained between the BD FACSPresto poc system and other single platform methods. Bland–Altman plots showed interchangeability between two machines mean bias BD-FACSPresto vs PIMA= -126,522(-161,221 to -91,822) BD-FACSPresto vs FACSCount= -38,708 (-58,935 to -18,482) and FACSPresto vs FACSCALIBUR= 0,791(-11,908 to 13,491). Mean difference with Absolute CD4+ T-lymphocyte values obtained from the BD FACSPresto system correlated well with PIMA, FACSCount, and FACSCalibur method with R² equal to 0.88, 0.92 and 0.968 respectively with P < 0.001 for all. The mean comparison between values obtained from BD FACSPresto with PIMA, FACSCount, and FACSCalibur using paired T test give P=0.17, P=0.5 and P=0.6 respectively meaning that there is no significant differences between values obtained with BD FACSPresto and PIMA, FACSCount or FACSCalibur CD4 enumeration machines. Further analysis revealed close agreement between all the three instruments with no significant difference between the four equipment with different methods of analysis (P=0.91) Conclusion: This BD-FACSPresto POC system is a simple, robust and reliable system for enumeration of absolute and CD4+ T-lymphocytes percentages especially in remote areas with limited resources. Having a single BD-FACSPresto POC system which is easy to use, should reduce the cost and thus increase and improved access to CD4 testing for HIV infected patients in remote areas of resource-constrained countries. BD-FACSPresto POC CD4 will enable reduction in patient wait time and improve the overall quality of ART service count and may improve test access in remote areas. This technology can allow for greater decentralization and wider access to CD4 testing in areas where viral load is not possible during ART


2020 ◽  
Author(s):  
Bertrand Sagnia ◽  
Fabrice MBAKOP Ghomsi ◽  
Ana Gutierrez ◽  
Samuel SOSSO ◽  
Rachel KAMGAING ◽  
...  

Abstract Background: In the context of scaling the viral load in resource limited settings, following HIV infected patient’s adults and children with CD4+ T-lymphocyte count still very important in settings where the decentralization of treatment still has some challenges. Effective HIV monitoring in these resource-constrained settings needs affordable and reliable CD4+ T lymphocytes enumeration methods. We investigated the validity of a BD FACSPresto POC which is a dedicated system for enumeration that uses immunofluorescent technologies. In this study, we have assessed the correlation between most representative flow cytometry instruments present in Cameroon with more than 5000 CD4 T cells tests per year including FACSCalibur, FACSCount, and PIMA POC from Becton Dickinson and ALERE respectively. Methods: 268 patients aged from 1 to 72 years old were enrolled and included in the study. The BD FACSPresto POC CD4+ T cell technology was placed at CIRCB and operated by technician staff. HIV infected patients were from Chantal BIYA international reference Center (CIRCB), Centre de Sante Catholique de NKOLODOM, Centre de Sante Catholique de BIKOP and CASS de Nkolndongo – Yaounde We compared the accuracy of the BD FACSPresto and three existing reference technologies with more than 5000 tests per year like FACSCalibur, FACSCount and PIMA according to the number of CD4 test done per year and their repartition in the country. Bland – Altman method and correlation analysis were used to estimate mean bias and 95% limits of agreement and to compare the methods, including analysis by subgroup of participant gestational age. Statistical significance was set at p-value < 0.05Results: The BD FACSPresto POC system has excellent precision, accuracy and linearity for CD4+ T lymphocytes enumeration. Good correlations were obtained between the BD FACSPresto poc system and other single platform methods. Bland–Altman plots showed interchangeability between two machines mean bias BD-FACSPresto vs PIMA= -126,522(-161,221 to -91,822) BD-FACSPresto vs FACSCount= -38,708 (-58,935 to -18,482) and FACSPresto vs FACSCALIBUR= 0,791(-11,908 to 13,491). Mean difference with Absolute CD4+ T-lymphocyte values obtained from the BD FACSPresto system correlated well with PIMA, FACSCount, and FACSCalibur method with R² equal to 0.88, 0.92 and 0.968 respectively with P < 0.001 for all. The mean comparison between values obtained from BD FACSPresto with PIMA, FACSCount, and FACSCalibur using paired T test give P=0.17, P=0.5 and P=0.6 respectively meaning that there is no significant differences between values obtained with BD FACSPresto and PIMA, FACSCount or FACSCalibur CD4 enumeration machines. Further analysis revealed close agreement between all the three instruments with no significant difference between the forth methods (P=0.91) Conclusion: This BD-FACSPresto POC system is a simple, robust and reliable system for enumeration of absolute and percentage of CD4+ T-lymphocytes especially suitable for remote areas with limited resources. Having one BD-FACSPresto POC system easy to use, should reduce the cost and thus increase and improved access to CD4 testing for HIV infected patients in resource-constrained countries. BD-FACSPresto POC CD4 will enable reduction in patient time and improve the overall quality of ART service count and may improve test access in remote areas. This technology can allow for greater decentralization and wider access to CD4 testing and ART


2010 ◽  
Vol 34 (3) ◽  
pp. 945-954 ◽  
Author(s):  
Roriz Luciano Machado ◽  
Alexander Silva de Resende ◽  
Eduardo Francia Carneiro Campello ◽  
José Arimathéa Oliveira ◽  
Avílio Antônio Franco

The most advanced stage of water erosion, the gully, represents severe problems in different contexts, both in rural and urban environments. In the search for a stabilization of the process in a viable manner it is of utmost importance to assess the efficiency of evaluation methodologies. For this purpose, the efficiency of low-cost conservation practices were tested for the reduction of soil and nutrient losses caused by erosion from gullies in Pinheiral, state of Rio de Janeiro. The following areas were studied: gully recovered by means of physical and biological strategies; gullies in recovering stage, by means of physical strategies only, and gullies under no restoration treatment. During the summer of 2005/2006, the following data sets were collected for this study: soil classification of each of the eroded gully areas; planimetric and altimetric survey; determination of rain erosivity indexes; determination of amount of soil sediment; sediment grain size characteristics; natural amounts of nutrients Ca, Mg, K and P, as well as total C and N concentrations. The results for the three first measurements were 52.5, 20.5, and 29.0 Mg in the sediments from the gully without intervention, and of 1.0, 1.7 and 1.8 Mg from the gully with physical interventions, indicating an average reduction of 95 %. The fully recovered gully produced no sediment during the period. The data of total nutrient loss from the three gullies under investigation showed reductions of 98 % for the recovering gully, and 99 % for the fully recovered one. As for the loss of nutrients, the data indicate a nutrient loss of 1,811 kg from for the non-treated gully. The use of physical and biological interventions made it possible to reduce overall nutrient loss by more than 96 %, over the entire rainy season, as compared to the non-treated gully. Results show that the methods used were effective in reducing soil and nutrient losses from gullies.


Author(s):  
Romário Rosa de Sousa

LOW COST RAIN GAUGES AND RAINFALL VARIABILITY IN BARRA DO GARÇAS – MT (OCTOBER 2015 TO APRIL 2016)PLUVIÓMETRO DE BAJO COSTO Y LA VARIACIÓN DE LA LLUVIA EN EL MUNICIPIO DE BARRA DO GARÇAS – MT (OCTUBRE DE 2015 A ABRIL 2016)Este trabalho teve como objetivo principal confeccionar e distribuir vinte pluviômetros de baixo custo de PVC, dentro do município de Barra do Garças-MT, onde posteriormente a partir dos dados coletados, gerou-se um mapa pluviométrico da irregularidade da chuva. Os trabalhos metodológicos foram desenvolvidos em onze etapas distintas. Após toda a fase de aquisição dos materiais de baixo custo, na sequência realizou-se os seguintes procedimentos: confecção dos pluviômetros, aferição, instalação, treinamento dos produtores rurais, coleta de dados a campo, organização dos dados em planilha eletrônica com geração de relatório de tabela dinâmica, realização do processo de interpolação dos dados, geração do mapa pluviométrico, ajustes e finalização do mapa gerado, análise e discussão dos dados. É importante ressaltar que o processo de interpolação dos dados foi realizado no software ArcGis, 10.1. Ressalta-se que o processo de construção do pluviômetro de baixo custo, demonstrou que foi de grande ajuda, no sentido de baixar custos com um instrumento de grande importância para o meio rural e urbano. Também ficou comprovado que o pluviômetro de baixo custo, é um aparelho de credibilidade e confiabilidade nos registros dos dados pluviométricos. Quanto a distribuição pluviométrica da chuva no município de Barra do Garças-MT, foi bem diversificada e irregular para o período estudado, onde averiguou-se que o maior acumulo pluviométrico foi registrado no extremo sul do município com 986,1mm de chuva. E encontra partida um núcleo seco com um baixo volume de precipitação foi confirmado na porção leste com 146,2 mm de chuva.Palavras-chave: Pluviômetros; Chuva; PVC; Baixo Custo.ABSTRACTThis study aims to design, assemble and distribute twenty low cost PVC rain gauges in Barra do Garças-MT, where afterwards a rainfall map was generated from the collected data. The methodological works were developed in eleven distinct stages. Following the entire acquisition phase of the low cost materials, the following procedures were carried out: preparation of the rain gauges, gauging, installation, training of rural producers, data collection in the field, data organization in electronic spreadsheet making a dynamic table report, data interpolation, creating a rainfall map, adjustment and finalization of the created map, data analysis and discussion. It is important to note the data interpolation process was performed in ArcGis software, 10.1. It should be noted that the process of construction of the low cost rain gauge showed that it was of great help in order to reduce costs with an instrument of great importance for the rural and urban environments. It has also been proven that the low cost rain gauge is an apparatus of credibility and reliability in rainfall records. As for the rainfall distribution in Barra do Garças-MT, it was well diversified and irregular for the period studied, where it was verified that the highest rainfall accumulation was recorded in the southern end of the municipality with 986.1mm of rain. However, finding a dry core with a low volume of precipitation was confirmed in the eastern portion with 146.2mm of rain.Keywords: Rain Gauges; Rain; PVC; Low Cost.RESUMENEste trabajo tuvo como objetivo principal elaborar, montar y distribuir veinte pluviómetros de bajo costo de PVC, dentro del municipio de Barra do Garças-MT, posteriormente, a partir de los datos colectados, se originó un mapa pluviométrico de la irregularidad de la lluvia. Los trabajos metodológicos fueron desarrollados en once etapas distintas. Después de toda la fase de adquisición de los materiales de bajo costo, en seguida se realizaron los siguientes procedimientos: confección de los pluviómetros, calibración, instalación, entrenamiento de los productores rurales, colecta de datos a campo, organización de los datos en planilla electrónica con elaboración de un informe de tabla dinámica, realización del proceso de interpolación de los datos, producción del mapa pluviométrico, ajustes y finalización del mapa generado, análisis y discusión de los datos. Es importante realzar que el proceso de interpolación de los datos fueron realizados en el software ArcGis, 10.1. Se resalta que el proceso de construcción del pluviómetro de bajo costo, demostró que fue de gran ayuda, en el sentido de bajar costos con un instrumento de gran importancia para el medio rural y urbano. También quedó demostrado que el pluviómetro de bajo costo, es un aparato de credibilidad y confiabilidad en los registros de los datos pluviométricos. Cuanto a la distribución pluviométrica en el municipio de Barra do Garças-MT, fue bien diversificada e irregular para el periodo estudiado, donde se comprobó que el mayor acúmulo pluviométrico fue registrado en el extremo Sur del municipio con 986,1mm de lluvia. En contra partida un núcleo seco con un bajo volumen de precipitación fue confirmado en la región Este con 146,2 mm de lluvia.Palabras-clave: Pluviómetros; Lluvia; PVC; Bajo Costo.


2017 ◽  
Vol 23 (2) ◽  
pp. 134-143 ◽  
Author(s):  
Xianbo Qiu ◽  
Junhui Zhang ◽  
Shisong Gong ◽  
Dong Wang ◽  
Shan Qiao ◽  
...  

A single-bead-based, fully integrated microfluidic system has been developed for high-throughput CD4+T lymphocyte enumeration at point-of-care testing. Instead of directly counting CD4+T lymphocytes, CD4+T lymphocyte enumeration is achieved by quantitatively detecting CD4 antigen from the lysed blood sample with a functionalized polycarbonate single bead based on chemiluminescence. To implement the sandwiched chemiluminescence immunoassay with reduced nonspecific binding, a streamlined microfluidic chip with multiple reaction chambers is developed to allow each reaction step to be completed in an independent chamber where reagent is pre-stored. With simple magnetic control, the single bead with an embedded ferrous core can be consecutively transported between each of two adjacent chambers for different reactions. Meanwhile, enhanced mixing can be achieved by moving the single bead back and forth inside one chamber with magnetic actuation. High-throughput detection can be performed when a linear actuation stage is adopted to introduce synchronous magnetic control to multiple single beads in parallel microfluidic chips. A sensitive charge-coupled device (CCD) camera is adopted for high-throughput chemiluminescence detection from multiple single beads. Experimental results show that with the fully integrated microfluidic system, easy-to-operate, accurate, low-cost, immediate, and high-throughput CD4+T lymphocyte enumeration can be successfully achieved at resource-poor settings.


2014 ◽  
Vol 25 (13) ◽  
pp. 956-959 ◽  
Author(s):  
L Rathunde ◽  
GMB Kussen ◽  
MP Beltrame ◽  
LM Dalla Costa ◽  
SM Raboni

CD4 + lymphocyte counts are routinely ordered during the early phases of antiretroviral therapy and for prophylaxis of opportunistic infections in HIV-positive patients. Flow cytometry is the standard methodology for CD4 counts in Brazilian reference laboratories. However, these laboratories are located in large cities, frequently distant from patients, thus limiting patient access and delaying results. We compared a point-of-care test with flow cytometry determination of CD4+ T lymphocyte counts in HIV patients. We analysed 107 consecutive samples by both methods. Overall, the point-of-care test performed well, with excellent agreement between it and the standard method. Test results were concordant for patients with CD4+ T lymphocyte values above and below 200 cells/mm 3. The performance characteristics obtained were sensitivity 94% (95% CI 89.5–98.5%), specificity 93% (95% CI 88.2–97.8%), positive predictive value 86% (95% CI 79.4–92.6%), and negative predictive value 97% (95% CI 94–100%). The high sensitivity and specificity of the point-of-care test methodology suggest its utility as an alternative method for rapid measurement of CD4+ T lymphocytes in patients with limited access to reference laboratories, enabling prompt therapeutic intervention for patients at risk of progression to AIDS.


2018 ◽  
Vol 11 (6) ◽  
pp. 3569-3594 ◽  
Author(s):  
Ashley Collier-Oxandale ◽  
Joanna Gordon Casey ◽  
Ricardo Piedrahita ◽  
John Ortega ◽  
Hannah Halliday ◽  
...  

Abstract. Low-cost sensors have the potential to facilitate the exploration of air quality issues on new temporal and spatial scales. Here we evaluate a low-cost sensor quantification system for methane through its use in two different deployments. The first was a 1-month deployment along the Colorado Front Range and included sites near active oil and gas operations in the Denver-Julesburg basin. The second deployment was in an urban Los Angeles neighborhood, subject to complex mixtures of air pollution sources including oil operations. Given its role as a potent greenhouse gas, new low-cost methods for detecting and monitoring methane may aid in protecting human and environmental health. In this paper, we assess a number of linear calibration models used to convert raw sensor signals into ppm concentration values. We also examine different choices that can be made during calibration and data processing and explore cross sensitivities that impact this sensor type. The results illustrate the accuracy of the Figaro TGS 2600 sensor when methane is quantified from raw signals using the techniques described. The results also demonstrate the value of these tools for examining air quality trends and events on small spatial and temporal scales as well as their ability to characterize an area – highlighting their potential to provide preliminary data that can inform more targeted measurements or supplement existing monitoring networks.


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