Feasibility of low-cost particle sensor types in long-term indoor air pollution health studies after repeated calibration, 2019–2021

Abstract

Previous studies have explored using calibrated low-cost particulate matter (PM) sensors, but important research gaps remain regarding long-term performance and reliability. Evaluate longitudinal performance of low-cost particle sensors by measuring sensor performance changes over 2 years of use. 51 low-cost particle sensors (Airbeam 1 N = 29; Airbeam 2 N = 22) were calibrated four times over a 2-year timeframe between 2019 and 2021. Cigarette smoke-specific calibration curves for Airbeam 1 and 2 PM sensors were created by directly comparing simultaneous 1-min readings of a Thermo Scientific Personal DataRAM PDR-1500 unit with a 2.5 µm inlet. Inter-sensor variability in calibration coefficient was high, particularly in Airbeam 1 sensors at study initiation. Calibration coefficients for both sensor types trended downwards over time to < 1 at final calibration timepoint [Airbeam 1 Mean (SD) = 0.87 (0.20); Airbeam 2 Mean (SD) = 0.96 (0.27)]. We lost more Airbeam 1 sensors (N = 27 out of 56, failure rate 48.2%) than Airbeam 2 (N = 2 out of 24, failure rate 8.3%) due to electronics, battery, or data output issues. Evidence suggests degradation over time might depend more on particle sensor type, rather than individual usage. Repeated calibrations of low-cost particle sensors may increase confidence in reported PM levels in longitudinal indoor air pollution studies.

Motorized three-wheelers and their potential for just mobility in Caribbean urban areas

“…In China and the United States, Air beam units were used for spatial modeling of particulate matter air pollution sensor measurements collected by community scientists while cycling, land use regression with spatial cross-validation, and applications of machine learning for data correction; feasibility and acceptability of monitoring personal air pollution exposure with sensors for asthma self-management (Adams et al, 2020; Guevara-Luna et al, 2020; Xie et al, 2021). Although air sensors are not a replacement for regulatory monitors, they entail a valuable teaching tool (Anastasiou et al, 2022). The data may help the general public better understand the air quality in their communities.…”

Gaps and future directions in research on health effects of air pollution

“… 39 , 40 A significant body of research has now been done to test and use LCS for personal exposure monitoring, demonstrating their potential for use in research, with proper quality control. 38 , 39 , 41 , 42 Importantly, their advantages make low-cost sensors a strong candidate for studies in LMIC, where resources for environmental monitoring are more scarce.…”

“…Despite the numerous advantages of low-cost air monitoring sensors, their accuracy may be limited as measurements can be biased by variations in the ambient environment, inter-instrument variability, limitations in the range of concentrations that can be measured, and concentration plateauing due to signal saturation above certain levels - typically above 100 μg/m 3 . 41 , 43 They have also been found to underperform in lower pollution settings, demonstrating poor agreement with more advance instruments below 40 μg/m 3 . 44 Therefore, they are most accurate and have high agreement with reference instruments only within a particular range.…”

“… 42 , 43 Sensor ‘aging’ drift is also a concern. 41 In very high concentration situation LCS may also become saturated, and fail to accurately assess extreme concentrations. Therefore, scientists and the U.S. EPA have recommended periodic calibration of low-cost devices with more advanced or reference instruments to achieve data quality and accuracy.…”

“…Sensors estimate particle size using an internal algorithm, which at times have been found to be different from reference instruments. 41 However, overall, LCS present a great potential to be a powerful tool for augmenting central site air quality monitoring data with higher resolution, particularly for research in communities in LMIC and other areas that are unable to afford central site reference monitors.…”