DOI: 10.5281/zenodo.4936982
title: Leuvenair: 40 months of air quality measurements by citizens in the city of Leuven, Belgium

description: <strong>Leuvenair</strong> was a bottom-up citizen science project for mapping air quality in the city of Leuven (Belgium) at high spatial resolution, with low-cost particulate matter sensors. The project started on Jan 30, 2018 and ran for more than three years. The complete dataset contains 42,203,945 measurements of 112 sensors, in and around the city of Leuven. The Nova Fitness SDS011 sensors used in the project were equipped with the firmware developed by the <strong>Sensor.community</strong> initiative (formerly: Luftdaten.info). The sensors measure the concentration of PM2.5 and PM10 every 150 seconds. Additionally also temperature and relative humidity are measured with an extra sensor (DHT11) at each location. Measurements were sent in real-time to a server dedicated to the Leuvenair project, as well as to the global Sensor.community project. The dataset contains three files: <strong>LEUVENAIRfulldumpData.csv.gz</strong> actual datafile with all measurements, from 2018-01-30 till 2021-05-23 <strong>LEUVENAIRfulldumpMedian.csv.gz</strong> five-minute median of all active sensors <strong>LEUVENAIRfulldumpMeta.csv</strong> metadata of all measuring locations All timestamps are in UTC. The metadata table contains the following columns: <strong>SDS011ID</strong> : unique identifier of the SDS011 sensor (same as in sensor.community project) <strong>DHTID</strong> : unique identifier of the DHT11 sensor (same as in sensor.community project) <strong>LAT</strong> : latitude of the sensor location <strong>LON</strong> : longitude of the sensor location <strong>STREET</strong> : street name of the sensor location <strong>POSTALCODE</strong> : postal code of the sensor location <strong>CITY</strong> : (sub)municipality of the sensor location <strong>HEIGHT (cm)</strong> : height of the sensor, reported by the participant <strong>SENSOR POSITION</strong> : (qualitative index given by participant) 1 = on the garden side, very well shielded from all streets, 10 = the sensor is on a house wall directly on the street. With this value it is irrelevant how big the street is, it is only about where the sensor is attached to the house. <strong>INDUSTRY</strong> : (qualitative index given by participant) 10 = a lot of polluting industry in the immediate neighbourhood of the sensor, 1 = very rural area without industrial PM sources. <strong>WOODSTOVES</strong> : (qualitative index given by participant) 10 = a lot of wood burning in the immediate neighbourhood of the sensor, 1 = no wood burning in the area. <strong>TRAFFIC</strong> : (qualitative index given by participant) 10 = sensor close to very busy roads, 1 = very quiet area in terms of traffic. <strong>NO2_CN</strong> : the NO<sub>2</sub> concentration (yearly mean) at the same location as the PM sensor, taken from the CurieuzeNeuzen citizen science project. <strong>Acknowledgements</strong> In the startup phase, the Leuvenair project was kindly supported by the Straten Vol Leuven grassroots movement, the province of Vlaams-Brabant, and the city of Leuven. The Leuvenair project could count on the enthusiastic support of the following persons and organisations: <strong>Bert Cornillie</strong> (core group member Straten Vol Leuven) <strong>Wouter Florizoone</strong> (Facebook page and contact Provincie Vlaams-Brabant) <strong>Stad Leuven</strong>: Tim Guily (smart city policy advisor), Walter Op de Beeck (project coordinator Kom Op Voor Je Wijk) and Geert Vanhorebeek (sustainability coordinator) <strong>IRCEL/VMM: </strong>Frans Fierens, Olav Peeters and Jordy Vercauteren <strong>Data Science Leuven:</strong> Linde Vloeberghs and Kris Peeters <strong>Karel De Gendt</strong> : mobile helpdesk in startup phase
description: --- Some guidelines for the analysis --- - The PM2.5 measurements of the SDS011 sensor are much more reliable than the PM10 measurements. For long-term analyses, one should stick to the PM2.5 measurements. PM10 measurement can be used for peak detection only (e.g. in the case of very local PM sources). - The sensor will overestimate the PM concentration in humid conditions (relative humidity RH &gt; ~75%) and will underestimate the PM concentrations in dry conditions (RH &lt; ~40%). - The measurements of the DHT11 sensor (temperature + humidity) are not so reliable. Try to use an external source for temperature and relative humidity. - We saw some cases where the SDS011 sensor reported very high values for several hours, and then gradually returned to "normal" values. We believe this effect could be caused by some dirt inside the sensor. - There is some intrinsic sensor-to-sensor variability present in the sensors, which might even change over time. At some locations we have more than one sensor. The measurements at these locations can be used to quantify this effect.