Evaluation of optical particulate matter sensors under realistic conditions of strong and mild urban pollution

Abstract

Abstract. In this paper we evaluate characteristics of three optical particulate matter sensors/sizers (OPS): high-end spectrometer 11-D (Grimm, Germany), low-cost sensor OPC-N2 (Alphasense, United Kingdom) and in-house developed MAQS (Mobile Air Quality System), which is based on another low-cost sensor – PMS5003 (Plantower, China), under realistic conditions of strong and mild urban pollution. Results were compared against a reference gravimetric system, based on a Gemini (Dadolab, Italy), 2.3 m3 h−1 air sampler, with two channels (simultaneously measuring PM2.5 and PM10 concentrations). The measurements were performed in Sarajevo, the capital of Bosnia-Herzegovina, from December 2019 until May 2020. This interval is divided into period 1 – strong pollution – and period 2 – mild pollution. The city of Sarajevo is one of the most polluted cities in Europe in terms of particulate matter: the average concentration of PM2.5 during the period 1 was 83 µg m−3, with daily average values exceeding 500 µg m−3. During period 2, the average concentration of PM2.5 was 20 µg m−3. These conditions represent a good opportunity to test optical devices against the reference instrument in a wide range of ambient particulate matter (PM) concentrations. The effect of an in-house developed diffusion dryer for 11-D is discussed as well. In order to analyse the mass distribution of particles, a scanning mobility particle sizer (SMPS), which together with the 11-D spectrometer gives the full spectrum from nanoparticles of diameter 10 nm to coarse particles of diameter 35 µm, was used. All tested devices showed excellent correlation with the reference instrument in period 1, with R2 values between 0.90 and 0.99 for daily average PM concentrations. However, in period 2, where the range of concentrations was much narrower, R2 values decreased significantly, to values from 0.28 to 0.92. We have also included results of a 13.5-month long-term comparison of our MAQS sensor with a nearby beta attenuation monitor (BAM) 1020 (Met One Instruments, USA) operated by the United States Environmental Protection Agency (US EPA), which showed similar correlation and no observable change in performance over time.

Urban Air Quality Modeling Using Low-Cost Sensor Network and Data Assimilation in the Aburrá Valley, Colombia

“…The BAM PM analyzers employ the absorption of beta radiation by solid particles extracted from air flow [3]. These analyzers have gone through strict field evaluations and demonstrated that they could provide concentration measures equivalent to the filter-based GMM, with the advantage of being usable for continuous PM monitoring (generally with a temporal resolution of 1 h) [5]. Finally, the optical sensors measure particles' size by light scattering, so the concentration of PM can be detected according to the signal [3,6,7].…”

Development and evolution of an anomalous Asian dust event across Europe in March 2020

“…The event of mineral dust incursion from Central Asia herein described occurred at the end of March 2020 and, to the best of our knowledge, has not been so far the object of an in-depth analysis though it was mentioned in a few papers devoted to other topics (Masic et al, 2020;Šikoparija, 2020) or described qualitatively in remote sensing or meteorological web pages (Mahovic et al, 2020;SNPA, 2020).…”

The Aerosol Research Observation Station (AEROS)

“…Several studies examining the performance of the Grimm 11-D unit under diverse atmospheric and laboratory conditions have found it to be comparable to various reference units (Masic et al, 2020;Vasilatou et al, 2021). For example, Masic et al (2020) found that it performed well under diverse atmospheric and pollution conditions; when equipped with a dryer, it performed at a level comparable to that of a reference unit (a beta attenuation monitor).…”

“…These are made available through a Grimm proprietary algorithm, but the manufacturer does not share information about it, or the refractive index, density, and weighting factors used for the calculations. The Grimm 11-D and previous versions have been used in various indoor (Mølgaard et al, 2015) and atmospheric studies (Mukherjee et al, 2017;Stavroulas et al, 2020;Masic et al, 2020), including under dusty conditions (Jaafari et al, 2018). Several studies examining the performance of the Grimm 11-D unit under diverse atmospheric and laboratory conditions have found it to be comparable to various reference units (Masic et al, 2020;Vasilatou et al, 2021).…”

“…The Grimm 11-D and previous versions have been used in various indoor (Mølgaard et al, 2015) and atmospheric studies (Mukherjee et al, 2017;Stavroulas et al, 2020;Masic et al, 2020), including under dusty conditions (Jaafari et al, 2018). Several studies examining the performance of the Grimm 11-D unit under diverse atmospheric and laboratory conditions have found it to be comparable to various reference units (Masic et al, 2020;Vasilatou et al, 2021). For example, Masic et al (2020) found that it performed well under diverse atmospheric and pollution conditions; when equipped with a dryer, it performed at a level comparable to that of a reference unit (a beta attenuation monitor).…”