Comparison of high-volume and low-volume air samplers for particulate matter air pollution measurement in Rwanda, East Africa

Particulate matter (PM) air pollution is recognised as the leading cause of premature human mortality in Africa. However, air pollution monitoring is limited in African countries like Rwanda due to insufficient funding for operating the high-cost reference-grade stations used to measure real-time PM and the technical expertise required for calibrations. In this study, we compared the performance of the most commonly used air samplers (high- and low-volume air samplers (HI-VOL and LO-VOL)) for collecting PM₁₀ (particulate matter <10 μm) on a glass fibre filter. A total of 42 samples were analysed, with 21 from each sampler, collected simultaneously over a two-month period in two locations (rural and urban) in Rwanda. The 24-hour mean PM₁₀ concentrations exceeded the WHO air quality recommended limit at both sites. A Student's t-test indicated that the average 24-hour PM₁₀ concentrations at the urban site showed no significant difference between the HI-VOL and LO-VOL concentrations; however, at the rural site, significantly higher PM₁₀ concentrations were observed with the HI-VOL than the LO-VOL. Our results indicate that LO-VOL samplers were as effective as the standard HI-VOL and could be used in monitoring aerosols. LO-VOLs are significantly more affordable (saving about CAD 10,000) than HI-VOL options. Therefore, LO-VOL samplers have potential benefits and could serve as alternative and educational solutions for air quality data collection in Africa, where gravimetric PM mass and aerosol composition are scarce.