Comparison between real-time low-cost sensor and gravimetric sampling methods of particulate matter (PM2.5) in an urban background location, Zambia
1
1 School of Public Health and Environmental Sciences, Levy Mwanawasa Medical University, Lusaka/Lusaka, Zambia
2
2 School of Public Health and Environmental Sciences, Levy Mwanawasa Medical University, Lusaka/Lusaka, Zambia
3
3 School of Health Systems and Public Health, University of Pretoria, Pretoria, South Africa
Popul. Med. 2026;8(Supplement Supplement 1):A3673
ABSTRACT
INTRODUCTION:
Gravimetric methods serve as the standard reference for measuring PM2.5 1,2, while real-time low-cost sensors (LCS) offer continuous, immediate readings through light scattering or beta attenuation 3, making them ideal for tracking short-term fluctuations, source identification, and exposure dynamics in dynamic environments like urban areas 4,5. The study aimed to compare these two methods for PM2.5 data collection in Lusaka, Zambia.
METHODS:
The sampling site was on the roof of the Academic Building Block, Levy Mwanawasa Medical University, representing an urban background location. This is an ongoing, one-year observational environmental monitoring study. The gravimetric measurement applied a GilAir-5 pump (calibrated flow rate 4 L/min) fitted with a PM2.5 cyclone to collect PM2.5 on 37 mm Teflon (PTFE) membrane filters for 24 hours (9 am to 9 am) every fourth day. Sampling was conducted from September to November in 2025 (20 days). PM2.5 gravimetric analysis was conducted at the Air Quality Laboratory, SHSPH, University of Pretoria. A PurpleAir LCS continuously collected real-time PM2.5 data during the same study period. Preliminary results Across the monitoring period, the LCS method consistently reported substantially higher PM2.5 concentrations than the gravimetric method. The LCS measurements ranged from 20.82 to 76.2 µg/m³, with an average of 40.19 μg/m³. In contrast, the gravimetric method recorded markedly lower concentrations, ranging from 0.41 to 19.21 µg/m³, with an average of 3.25 μg/m³. Compared with the WHO 24-hour PM2.5 guideline of 15 µg/m³, the LCS method generated data exceeding it on several sampling days, whereas the gravimetric method data did not exceed it at any point during the study period.
CONCLUSIONS:
Preliminary findings indicate that LCS substantially overestimates PM2.5 concentrations relative to gravimetric measurements in an urban background setting in Lusaka, underscoring the need for site-specific calibration before LCS data are used for regulatory or health risk assessments.
Gravimetric methods serve as the standard reference for measuring PM2.5 1,2, while real-time low-cost sensors (LCS) offer continuous, immediate readings through light scattering or beta attenuation 3, making them ideal for tracking short-term fluctuations, source identification, and exposure dynamics in dynamic environments like urban areas 4,5. The study aimed to compare these two methods for PM2.5 data collection in Lusaka, Zambia.
METHODS:
The sampling site was on the roof of the Academic Building Block, Levy Mwanawasa Medical University, representing an urban background location. This is an ongoing, one-year observational environmental monitoring study. The gravimetric measurement applied a GilAir-5 pump (calibrated flow rate 4 L/min) fitted with a PM2.5 cyclone to collect PM2.5 on 37 mm Teflon (PTFE) membrane filters for 24 hours (9 am to 9 am) every fourth day. Sampling was conducted from September to November in 2025 (20 days). PM2.5 gravimetric analysis was conducted at the Air Quality Laboratory, SHSPH, University of Pretoria. A PurpleAir LCS continuously collected real-time PM2.5 data during the same study period. Preliminary results Across the monitoring period, the LCS method consistently reported substantially higher PM2.5 concentrations than the gravimetric method. The LCS measurements ranged from 20.82 to 76.2 µg/m³, with an average of 40.19 μg/m³. In contrast, the gravimetric method recorded markedly lower concentrations, ranging from 0.41 to 19.21 µg/m³, with an average of 3.25 μg/m³. Compared with the WHO 24-hour PM2.5 guideline of 15 µg/m³, the LCS method generated data exceeding it on several sampling days, whereas the gravimetric method data did not exceed it at any point during the study period.
CONCLUSIONS:
Preliminary findings indicate that LCS substantially overestimates PM2.5 concentrations relative to gravimetric measurements in an urban background setting in Lusaka, underscoring the need for site-specific calibration before LCS data are used for regulatory or health risk assessments.
| eISSN: | 2654-1459 |
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