| 1. |
- Ahumada, Sofía, et al.
(författare)
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Calibration of SO2 and NO2 Electrochemical Sensors via a Training and Testing Method in an Industrial Coastal Environment
- 2022
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Ingår i: Sensors. - : IVL Svenska Miljöinstitutet. - 1424-8220. ; 22:19, s. 7281-7281
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Tidskriftsartikel (refereegranskat)abstract
- Low-cost sensors can provide inaccurate data as temperature and humidity affect sensoraccuracy. Therefore, calibration and data correction are essential to obtain reliable measurements.This article presents a training and testing method used to calibrate a sensor module assembledfrom SO2 and NO2 electrochemical sensors (Alphasense B4 and B43F) alongside air temperature (T)and humidity (RH) sensors.Field training and testing were conducted in the industrialized coastalarea of Quintero Bay, Chile. The raw responses of the electrochemical (mV) and T-RH sensors weresubjected to multiple linear regression (MLR) using three data segments, based on either voltage(SO2 sensor) or temperature (NO2). The resulting MLR equations were used to estimate the referenceconcentration. In the field test, calibration improved the performance of the sensors after addingT and RH in a linear model.The most robust models for NO2 were associated with data collectedat T < 10 C (R2 = 0.85), while SO2 robust models (R2 = 0.97) were associated with data segmentscontaining higher voltages. Overall, this training and testing method reduced the bias due to T andHR in the evaluated sensors and could be replicated in similar environments to correct raw data fromlow-cost electrochemical sensors. A calibration method based on training and sensor testing afterrelocation is presented. The results show that the SO2 sensor performed better when modeled fordifferent segments of voltage data, and the NO2 sensor model performed better when calibrated fordifferent temperature data segments.
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| 2. |
- Langner, J., et al.
(författare)
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Model-simulated source contributions to PM2.5 in Santiago and the central region of Chile
- 2020
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Ingår i: Aerosol and Air Quality Research. - : Taiwan Association for Aerosol Research. - 2071-1409 .- 1680-8584. ; 20:5, s. 1111-1126
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Tidskriftsartikel (refereegranskat)abstract
- The contributions to PM2.5 from different emission sectors across central Chile and the Santiago metropolitan area during summer/fall and winter have been evaluated using a chemical transport model. The simulations generally underestimate the mean PM2.5 concentrations compared to measurements conducted at stations in Santiago that belong to the Chilean National Air Quality Information System (SINCA). The potential reasons for this discrepancy include underestimated direct PM2.5 emissions, missing emissions for semi-and intermediately volatile organic compounds (SVOCs and IVOCs) and overestimated wind speeds in the simulations. The simulated winter PM2.5 concentrations in Santiago are lower and higher than the values observed during nighttime, and daytime and late evening, respectively, which may be related to excessive simulated wind speeds, as well as to uncertainties in the diurnal variation in the emissions. During summer/fall, the simulated diurnal variation better agrees with the observations, but the peak concentrations during the morning are underestimated, whereas those during the evening are overestimated. The simulated contributions of different aerosol components to the PM2.5 at one station in Santiago are all lower than the observed values, except for elemental carbon equivalent black carbon (BCe), which exhibit comparable or higher levels in the simulations. The absolute differences are the largest for the total organic matter, whereas the relative differences are the largest for BCe and ammonium. The simulated sector contributions indicate that emissions originating from transport and construction machinery dominate the PM2.5 in Santiago; however, residential wood combustion is the primary source in other urban areas of central Chile, except near major point sources. Away from urban areas, traffic routes and major industrial sources, secondary inorganic aerosol (SIA) is estimated to be the largest component of the aerosol, whereas the simulated secondary organic aerosol (SOA) only contributes a small fraction.
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| 3. |
- Lepistö, Teemu, et al.
(författare)
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Particle lung deposited surface area (LDSAal) size distributions in different urban environments and geographical regions : Towards understanding of the PM2.5 dose–response
- 2023
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Ingår i: Environment International. - : Elsevier. - 0160-4120 .- 1873-6750. ; 180
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Tidskriftsartikel (refereegranskat)abstract
- Recent studies indicate that monitoring only fine particulate matter (PM2.5) may not be enough to understand and tackle the health risk caused by particulate pollution. Health effects per unit PM2.5 seem to increase in countries with low PM2.5, but also near local pollution sources (e.g., traffic) within cities. The aim of this study is to understand the differences in the characteristics of lung-depositing particles in different geographical regions and urban environments. Particle lung deposited surface area (LDSAal) concentrations and size distributions, along with PM2.5, were compared with ambient measurement data from Finland, Germany, Czechia, Chile, and India, covering traffic sites, residential areas, airports, shipping, and industrial sites. In Finland (low PM2.5), LDSAal size distributions depended significantly on the urban environment and were mainly attributable to ultrafine particles (<100 nm). In Central Europe (moderate PM2.5), LDSAal was also dependent on the urban environment, but furthermore heavily influenced by the regional aerosol. In Chile and India (high PM2.5), LDSAal was mostly contributed by the regional aerosol despite that the measurements were done at busy traffic sites. The results indicate that the characteristics of lung-depositing particles vary significantly both within cities and between geographical regions. In addition, ratio between LDSAal and PM2.5 depended notably on the environment and the country, suggesting that LDSAal exposure per unit PM2.5 may be multiple times higher in areas having low PM2.5 compared to areas with continuously high PM2.5. These findings may partly explain why PM2.5 seems more toxic near local pollution sources and in areas with low PM2.5. Furthermore, performance of a typical sensor based LDSAal measurement is discussed and a new LDSAal2.5 notation indicating deposition region and particle size range is introduced. Overall, the study emphasizes the need for country-specific emission mitigation strategies, and the potential of LDSAal concentration as a health-relevant pollution metric.
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| 4. |
- Martikainen, Maria-Viola, et al.
(författare)
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TUBE project: Transport-derived ultrafines and the brain effects
- 2022
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Ingår i: International Journal of Environmental Research and Public Health. - : MDPI. - 1661-7827 .- 1660-4601. ; 19:1
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Tidskriftsartikel (refereegranskat)abstract
- The adverse effects of air pollutants on the respiratory and cardiovascular systems are unquestionable. However, in recent years, indications of effects beyond these organ systems have become more evident. Traffic-related air pollution has been linked with neurological diseases, exacerbated cognitive dysfunction, and Alzheimer’s disease. However, the exact air pollutant compositions and exposure scenarios leading to these adverse health effects are not known. Although several components of air pollution may be at play, recent experimental studies point to a key role of ultrafine particles (UFPs). While the importance of UFPs has been recognized, almost nothing is known about the smallest fraction of UFPs, and only >23 nm emissions are regulated in the EU. Moreover, the role of the semivolatile fraction of the emissions has been neglected. The Transport-Derived Ultrafines and the Brain Effects (TUBE) project will increase knowledge on harmful ultrafine air pollutants, as well as semivolatile compounds related to adverse health effects. By including all the major current combustion and emission control technologies, the TUBE project aims to provide new information on the adverse health effects of current traffic, as well as information for decision makers to develop more effective emission legislation. Most importantly, the TUBE project will include adverse health effects beyond the respiratory system; TUBE will assess how air pollution affects the brain and how air pollution particles might be removed from the brain. The purpose of this report is to describe the TUBE project, its background, and its goals.
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| 5. |
- Tagle, Matias, et al.
(författare)
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Field performance of a low-cost sensor in the monitoring of particulate matter in Santiago, Chile
- 2020
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Ingår i: Environmental Monitoring & Assessment. - : Springer. - 0167-6369 .- 1573-2959. ; 192:3
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Tidskriftsartikel (refereegranskat)abstract
- Integration of low-cost air quality sensors with the internet of things (IoT) has become a feasible approach towards the development of smart cities. Several studies have assessed the performance of low-cost air quality sensors by comparing their measurements with reference instruments. We examined the performance of a low-cost IoT particulate matter (PM10 and PM2.5) sensor in the urban environment of Santiago, Chile. The prototype was assembled from a PM10–PM2.5 sensor (SDS011), a temperature and relative humidity sensor (BME280) and an IoT board (ESP8266/Node MCU). Field tests were conducted at three regulatory monitoring stations during the 2018 austral winter and spring seasons. The sensors at each site were operated in parallel with continuous reference air quality monitors (BAM 1020 and TEOM 1400) and a filter-based sampler (Partisol 2000i). Variability between sensor units (n = 7) and the correlation between the sensor and reference instruments were examined. Moderate inter-unit variability was observed between sensors for PM2.5 (normalized root-mean-square error 9–24%) and PM10 (10–37%). The correlations between the 1-h average concentrations reported by the sensors and continuous monitors were higher for PM2.5 (R2 0.47–0.86) than PM10 (0.24–0.56). The correlations (R2) between the 24-h PM2.5 averages from the sensors and reference instruments were 0.63–0.87 for continuous monitoring and 0.69–0.93 for filter-based samplers. Correlation analysis revealed that sensors tended to overestimate PM concentrations in high relative humidity (RH > 75%) and underestimate when RH was below 50%. Overall, the prototype evaluated exhibited adequate performance and may be potentially suitable for monitoring daily PM2.5 averages after correcting for RH.
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