Low-Cost Air Quality Sensors: One-Year Field Comparative Measurement of Different Gas Sensors and Particle Counters with Reference Monitors at Tušimice Observatory

Petra Bauerová,Josef Keder,Adriana Šindelářová,Štěpán Rychlík,Zbyněk Novák

doi:10.3390/atmos11050492

Petra Bauerová, Josef Keder + Show 3 more

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https://doi.org/10.3390/atmos11050492

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Abstract

With attention increasing regarding the level of air pollution in different metropolitan and industrial areas worldwide, interest in expanding the monitoring networks by low-cost air quality sensors is also increasing. Although the role of these small and affordable sensors is rather supplementary, determination of the measurement uncertainty is one of the main questions of their applicability because there is no certificate for quality assurance of these non-reference technologies. This paper presents the results of almost one-year field testing measurements, when the data from different low-cost sensors (for SO2, NO2, O3, and CO: Cairclip, Envea, FR; for PM1, PM2.5, and PM10: PMS7003, Plantower, CHN, and OPC-N2, Alphasense, UK) were compared with co-located reference monitors used within the Czech national ambient air quality monitoring network. The results showed that in addition to the given reduced measurement accuracy of the sensors, the data quality depends on the early detection of defective units and changes caused by the effect of meteorological conditions (effect of air temperature and humidity on gas sensors and effect of air humidity with condensation conditions on particle counters), or by the interference of different pollutants (especially in gas sensors). Comparative measurement is necessary prior to each sensor’s field applications.

Highlights

To other countries, in the Czech Republic, the public’s interest in the current state of ambient air quality is increasing, especially in cities and locations exposed to industrial sources of pollution
The aim of this study is to show the performance of different Cairpol gas sensor pairs (Cairclip for SO2, NO2, O3, and CO) and miniature Plantower (PMS7003) and Alphasense (OPC-N2) particle counter pairs within almost one year of continuous field comparative measurement with the corresponding reference monitors and equivalent optical particle monitor used in the Czech Hydrometeorological Institute (CHMI) ambient air quality network
The summary statistic of concentrations measured by different Cairclip gas sensors and by corresponding reference monitors (RMs) is listed in Table 3

Summary

Introduction

In the Czech Republic, the public’s interest in the current state of ambient air quality is increasing, especially in cities and locations exposed to industrial sources of pollution. The national air quality network is representatively deployed over the entire territory, covering all types of monitoring sites (urban, industrial, and background) and potential air pollution sources (traffic, agricultural, and industrial), requests to widen the spatial resolution of the measurement network (to almost personal exposure) are still increasing in the public sector [1,2,3]. During the last three years, the Czech Hydrometeorological Institute (CHMI) has recorded several requests for assistance in processing data from public projects that applied sensors in cities or other places of interest. Most of these projects suffered from severe shortcomings in the following points: Clearly defined sensor application targets; Appropriate sensor placement (study design) to monitor the given target; Atmosphere 2020, 11, 492; doi:10.3390/atmos11050492 www.mdpi.com/journal/atmosphere. This paper deals with the two main points highlighted in bold above (sensor type selection and measurement quality control)

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