Low-Cost Air Quality Stations’ Capability to Integrate Reference Stations in Particulate Matter Dynamics Assessment

Abstract

Low-cost air quality stations can provide useful data that can offer a complete picture of urban air quality dynamics, especially when integrated with daily measurements from reference air quality stations. However, the success of such deployment depends on the measurement accuracy and the capability of resolving spatial and temporal gradients within a spatial domain. In this work, an ensemble of three low-cost stations named “AirQino” was deployed to monitor particulate matter (PM) concentrations over three different sites in an area affected by poor air quality conditions. Data of PM2.5 and PM10 concentrations were collected for about two years following a protocol based on field calibration and validation with a reference station. Results indicated that: (i) AirQino station measurements were accurate and stable during co-location periods over time (R2 = 0.5–0.83 and RMSE = 6.4–11.2 μg m−3; valid data: 87.7–95.7%), resolving current spatial and temporal gradients; (ii) spatial variability of anthropogenic emissions was mainly due to extensive use of wood for household heating; (iii) the high temporal resolution made it possible to detect time occurrence and strength of PM10 concentration peaks; (iv) the number of episodes above the 1-h threshold of 90 μg m−3 and their persistence were higher under urban and industrial sites compared to the rural area.

Performance Assessment of Two Low-Cost PM2.5 and PM10 Monitoring Networks in the Padana Plain (Italy)

“…After deploying an AirQino unit close to an ARPA reference station in Florence (Italy) across a full “heating season” (November 2016 to April 2017), Cavaliere et al [ 35 ] returned scores in measuring both PM 2.5 (MB = +4.39 μg/m 3 , RMSE = 7.95 μg/m 3 and R 2 = 0.90) and PM 10 daily concentrations (MB = +0.72 μg/m 3 , RMSE = 7.80 μg/m 3 and R 2 = 0.84) better than those achieved in the Padana Plain ( Table 4 and Table 5 ). Within a 78-day co-location vs. an ARPA station in Capannori (Italy) across a spring period in 2019, Brilli et al [ 36 ] reported AirQino scores in measuring PM 2.5 daily concentrations to be both better (RMSE = 4.2 μg/m 3 vs. 7.9–14.6 μg/m 3 ) and worse (R 2 = 0.54 vs. 0.37–0.78) than those achieved in the present study ( Table 4 ). The AirQino scores reported in the same study in monitoring PM 10 daily concentrations were better in terms of RMSE (4.6 μg/m 3 ) and comparable in terms of R 2 (0.63, Table 5 ).…”

“…As detailed in the Supplementary Material of [ 34 ], the AirQino-integrated PM sensors were subject to various calibration and validation processes in recent years in central Italy [ 35 , 36 ]. The units were also tested in opposite extreme environments such as the Arctic region [ 37 ] and the Sub-Saharan Africa [ 34 ], thus proving capable of covering a full spectrum of climatic conditions and PM concentrations.…”

Low‐cost air quality monitoring networks for long‐term field campaigns: A review

“…In the case of pollutants monitored daily such as PM, for example, the high temporal resolution of LC sensor measurements could support the introduction into air quality regulations of intra-daily limits in addition to the current daily ones. As shown, for example, in Brilli et al (2021), this would dramatically increase the assessment of population exposure to PM levels, but also would foster a better understanding of the dynamics and location of the emission sources.…”