Field evaluation of low-cost particulate matter sensors in high and low concentration environments

Abstract

Abstract. Low-cost particulate matter (PM) sensors are promising tools for supplementing existing air quality monitoring networks. However, the performance of the new generation of low-cost PM sensors under field conditions is not well understood. In this study, we characterized the performance capabilities of a new low-cost PM sensor model (Plantower model PMS3003) for measuring PM2.5 at 1 min, 1 h, 6 h, 12 h and 24 h integration times. We tested the PMS3003s in both low concentration suburban regions (Durham and Research Triangle Park (RTP), NC, US) with 1 h PM2.5 (mean ± Std.Dev) 15 of 9 ± 9 µg m -3 and 10 ± 3 µg m -3 respectively, and a high concentration urban location (Kanpur, India) with 1 h PM2.5 of 36 ± 17 µg m -3 and 116 ± 57 µg m -3 during monsoon and post-monsoon seasons, respectively. In Durham and Kanpur, the sensors were compared to a research-grade instrument (environmental b-attenuation monitor (E-BAM)) to determine how these sensors perform across a range of PM2.5 concentrations and meteorological factors (e.g., temperature and relative humidity (RH)). In RTP, the sensors were compared to three Federal Equivalent Methods (FEMs) including two Teledyne 20 Model T640s and a ThermoScientific Model 5030 SHARP to demonstrate the importance of the type of reference monitor selected for sensor calibration. The decrease of 1 h mean errors of the calibrated sensors using univariate linear models from Durham (201%) to Kanpur monsoon (46%) and to post-monsoon (35%) season showed that PMS3003 performance generally improved as ambient PM2.5 increased. The precision of reference instruments (T640: ±0.5 µg m -3 for 1 h; SHARP:±2 µg m -3 for 24 h, better than the E-BAM) is critical in evaluating sensor performance and b-attenuation-based monitors 25 may not be ideal for testing PM sensors at low concentrations, as underscored by 1) the less dramatic error reduction over averaging times in RTP against optical-based T640 (from 27% for 1 h to 9% for 24 h) than in Durham (from 201% to 15%);2) the lower errors in RTP than Kanpur post-monsoon season (from 35% to 11%); 3) the higher T640-PMS3003s correlations (R 2 ³ 0.63) than SHARP-PMS3003s (R 2 ³ 0.25). A major RH influence was found in RTP (1 h RH = 64 ± 22%) due to the relatively high precision of the T640 measurements that can explain up to ~30% of the variance in 1 min to 6 h 30 PMS3003 PM2.5 measurements. When proper RH corrections are made by empirical non-linear equations after using a more precise reference method to calibrate the sensors, our work suggests that the PMS3003s can measure PM2.5 concentrations within ~10% of ambient values. We observed that PMS3003s appeared to exhibit a non-linear response when ambient PM2.5

Field performance of a low-cost sensor in the monitoring of particulate matter in Santiago, Chile

“…Kuula et al (2019) showed that inter-unit variability decreased as concentrations increased. In the same study, a magnitude of 264% of nRMSE was calculated for the Shinyei PPD60PV at low concentrations (< 4 μg m −3 ), which supports indications that performance of low-cost sensors improves as the PM concentration increases, since low concentrations are usually close to the noise level Zheng et al 2018). Nevertheless, high concentrations could be considered potentially negative, as a higher amount of particles can cause saturation of the photodetector and lead to poor performance.…”

“…Since most low-cost PM sensors calculate concentrations based on the principle of light scattering, environmental variables such as temperature and relative humidity (RH) may significantly bias their measurements. Research conducted to date suggests the performance of the sensors decreases in environments with RH ≥ 75%, mainly due to hygroscopic growth of the particles after condensation of water droplets (Zheng et al 2018;Jayaratne et al 2018;Crilley et al 2018).…”

Measurements of PM&lt;sub&gt;2.5&lt;/sub&gt; with PurpleAir under atmospheric conditions

“…Holstius et al (2014) found a negligible effect of temperature or RH on measurements performed using low-cost sensors under ambient conditions. However, several studies that used old PMS units, such as PMS1003 that was used in PA-I or PMS3003 that was never used in any PA units, found that these sensors were affected by RH (Kelly et al, 2017;Jayaratne et al, 2018;Zheng et al, 2018). AQ-SPEC (2018) tested the PA-II unit in a laboratory setting under different temperature and RH conditions and found that most temperature and RH combinations had 380 a minimal effect on the PA-II's precision.…”

Collaborative Efforts to Investigate Emissions From Residential and Municipal Trash Burning in India

“…The sensor package used a light-scattering PM 2.5 sensor (Plantower PMS3003) that had previously been evaluated against researchgrade reference monitors over different seasons and in both low-and high-PM environments (including in urban India). 4 Sensor packages documented minute-averaged concentrations of PM 2.5 , and were powered by a small external battery pack ( Figure 1). The UAV itself detected the elevation from ground level and carried a high-resolution camera capable of capturing both still images and video.…”