142 research outputs found
Characterisation and calibration of PM sensors at high temporal resolution
No full textThis repository contains the data used for the Chapter 7 of my PhD thesis: Bulot, Florentin (2022) Systematic studies of commodity particulate matter air pollution sensors. University of Southampton, Doctoral Thesis, 272pp. http://eprints.soton.ac.uk/id/eprint/458166
It contains three files: fidas_10s.csv - contains the PM concentration data from the Fidas 200S rh_temperature.csv - contains the relative humidity and temperature data recorded by each of the SHT35 sensors in each air quality monitor sensors_10s_avg.zip - a zip file containing sensors_10s_avg.csv which contains the PM concentration data measured by the commodity PM sensors from Plantower PMS5003 and Sensirion SPS30 models</span
LoRaWAN for city scale IoT deployments
No full textData set to accompany paper, Basford, P. J., Johnston, S., Apetroaie-Cristea, M., Bulot, F., & Cox, S. (2019). LoRaWAN for city scale IoT deployments. Paper presented at Global IoT Summit, Aarhus, Denmark. https://doi.org/10.1109/GIOTS.2019.8766359</span
Inaugural-Predig von dem Fridens-Wunsch der Predigeren dess h. Evangeliums
No full textgehalten im Grossen Münster zu Zürich, den 3. Tag Junii 1668 durch Ulrich Bulod, den 16. Tag Aprilis 1668 erwehlten Diaconum daselbstBogensignaturen: A-B⁴, C²Titelbordür
Long-term outdoor comparison of low-cost particulate matter sensors in an urban environment
No full textComparison of the field performances of multiple low-cost particulate matter sensors in an urban area
No full textIntroduction: Exposure to particulate matter (PM) is one of the leading causes of morbidity and mortality worldwide. Understanding personal exposure requires higher spatial resolution than provided by a small number of reference stations. “Low-cost” PM sensors may provide an opportunity to improve spatial resolution of PM monitoring, but there are uncertainties regarding the reliability of their data. The aim of this work was to characterise the in-field performance of four models of low-cost PM sensor.Methods: Six air quality monitoring boxes, each containing one of each of four models of PM sensor (Plantower PMS5003, Plantower PMS7003, Alphasense OPC-N2 and Honeywell HPMA115S0), and temperature and relative humidity sensors, were installed at three locations at each of two schools in Southampton between February and September 2018. Sensor performance was assessed by comparing reported PM concentrations (1Hz, n=500,000 readings per individual sensor) between sensors within the same box, across sites, and with a background reference station. Effects of PM concentration and meteorological factors on sensor performance are discussed.Results: PM10/PM2.5 correlation varied between sensor models, suggesting different methods of determination. Agreement of sensor readings with background reference concentrations varied with levels of background pollution, relative humidity, months and wind direction.Conclusions: We have observed substantial variation between models of sensors and suitable agreement between the sensors but also with the reference station. Improved understanding of factors influencing sensor performance will inform interpretation of data from deployment of further monitors as part of a forthcoming city-wide PM-monitoring networ
Long-term outdoor comparison of low-cost particulate matter sensors in an urban environment and potential uses
No full textIntroduction: Exposure to particulate matter (PM) is one of the leading causes of morbidity and mortality worldwide. Understanding personal exposure requires a higher spatiotemporal resolution than provided by current reference stations. Low-cost PM sensors may facilitate improved spatiotemporal resolution of PM monitoring, but there are uncertainties regarding the reliability of their data. This work aims to characterise the in-field performance of four models of low-cost PM sensor.Method: Three PM monitoring boxes, each containing one of each of four models of low-cost PM sensors (2xPlantower, Alphasense, Honeywell), and temperature/relative humidity sensors, were installed at each of two schools in Southampton. Sensor performance was assessed by comparing reported PM concentrations between sensors within the same box, across sites, and with a background reference monitoring station. Effects of PM concentration and meteorological factors on sensor performance were analysed and response to short-lived events was observed.Results: Sensors present good agreement between each other (Pearson r>0.9, p<0.0001). Inter-model differences were observed including temporal drift for some models of sensors and different behaviour against relative humidity. All models present similar variability with background reference concentrations. Response to spikes of pollution also varies across sensor models. Low-cost PM sensors are suitable to detect and track short-lived events of pollution when used as a network as well as tracking hourly variation of pollution and obtained moderate to good agreement with reference instruments for hourly data (0.61<r<0.88, p<0.0001).Conclusion: Inter-model variability suggests that sensors should not be deployed individually. Variations between different models of sensors imply that different correction methods should be applied for different models of sensors. The low-cost PM sensors analysed are suitable to track short-lived events of pollution and deployment of a dense network of these sensors may provide useful information for personal exposure assessment and interventions evaluation across urban environments
Low-cost particulate matter sensors in an urban environment: characterisation and potential uses
No full textDissertatio de duratione mundi
No full textquam ... praeside ... Johanne Lavatero ... placidae disquisitioni subjicit Joh. Henricus Bulodius, ss. theologiae studiosus, a. & r. ...Widmungsbrief an Joh. Heinrich Lavater auf dem Titelbl. versoDiss. Hohe Schule Zürich, 167
Systematic studies of commodity particulate matter air pollution sensors
No full textAir pollution exposure is a leading risk factor for morbidity and mortality, with particulate matter (PM) generally being associated with the greatest health impact of all measured pollutants. PM concentrations vary spatiotemporally from micro- to cityto regional-scales, depending on sources and meteorological conditions. Commodity PM sensors, defined as PM sensors with characteristics that make them suitable for large scale deployment (size, ease of use, price and frequency of measurement), often qualified as ’low-cost’, are based on nephelometry and they could increase the spatiotemporal resolution of current monitoring. However, questions remain about their performance variation, including with PM characteristics and meteorological factors. There is no current agreed best practice to certify the performances of these sensors, especially at fine temporal resolutions. This study aimed to characterise multiple commodity PM sensors by comparing their performance to reference-grade instruments and to evaluate methods to calibrate them. The initial work developed the capabilities to utilise multiple commodity PM sensors in outdoor studies. Next, the performances of multiple commodity PM sensor models were compared during a yearlong outdoor campaign. To further characterise observed behaviour, a laboratory study was then conducted focusing on the transient response of the sensors. Finally, the sensors were collocated with a reference instrument with a similar time resolution, to evaluate a range of calibration models and strategies and propose improvements to existing sensor certifications. Sensors from different manufacturers demonstrated differential response to relative humidity. Sensors could detect transient PM peaks in the field and under controlled conditions. In the latter, a differential response was demonstrated for two combustion sources of PM, varying by sensor model and humidity. For calibration at a 2 min resolution, models incorporating sensor-reported particle number concentration, coupled with pre- and post-deployment calibration, showed potential for correcting these sensors to reach uncertainty around 25% and precision <2.5 µg/m3, similar to reference instruments minimum standards. These results show that, with careful calibration and assessment of environmental conditions, commodity PM sensors can accurately report PM air pollution concentrations and that there is scope to improve existing certification efforts. Further work is needed to evaluate their applicability in specific use-case scenarios, such as assessment of personal exposure while moving within different environments, or assessment of the impact of mitigation measures feeding back to policymaking or facilitating source identification
Chemical composition and biological activities of essential oil from <i>Grewia bulot</i> leaves
No full textThis study focused on the chemical composition and biological activities of the essential oil derived from Grewia bulot, a plant species known for its medicinal properties. The analysis of Grewia bulot essential oil revealed the presence of 78 constituents. The major compounds were α-cadinol (13.5%), 1,8-cineole (12.7%), 1,10-di-epi-cubenol (9.8%), epi-α-cadinol (6.7%), (E,E)-α-farnesene (5.9%), (E)-citral (4.0%), selin-11-en-4-α-ol (4.0%), citronellol isobutanoate (3.9%), and geranic acid (3.7%). The essential oil exhibited promising antioxidant potential with an IC50 value of 452.65 ± 28.40 µg/mL in DPPH model. This oil did not show NO production inhibitory effect in RAW 264.7 cells. In addition, the essential oil exhibited significant cytotoxicity against KB, Hep-G2, MCF-7, and SK-LU-1 cancer cell lines, with IC50 values ranging from 44.04 ± 1.47 to 74.20 ± 3.71 μg/mL.</p
- …
