Clean Air Blog

Accurate PM2.5 measurement matters if you want to understand real-world air pollution exposure indoors. While many low-cost air quality monitors claim to measure PM2.5, actual performance can vary significantly between models. To better understand how different consumer-grade monitors compare, we looked at a group of commonly used models from Qingping and Temtop. Rather than relying only on manufacturer claims, we anchored our comparison to models with independent field test data, then examined how closely the remaining units tracked alongside them in real indoor conditions. All six monitors were co-located on the same bench and run continuously over several days. While absolute readings varied slightly, the overall patterns and trends moved together closely, with relatively small gaps between devices. This provides useful context for how these monitors behave in practice, particularly when used to track changes and spikes in PM2.5 rather than focusing on a single absolute number. Independent Testing Anchors Southcoast AQMD, based in California has a program where they compare air quality monitors with high grade reference equipment. This provides independent test data for dozens of models, from low cost ones like the QP Lite to ones costing thousands of dollars. For PM2.5, all the results are published here. Several units already have results available from Southcoast AQMD. All showed strong correlations with the reference equipment for PM2.5 measurements, and low mean errors - often beating monitors costing thousands of dollars!  Model Field R2 (Correlation) Field MAE (Absolute Error) Qingping Lite 0.85 to 0.93 1.8 to 3.6 Qingping Pro 0.86 to 0.90 1.8 to 2.3 Temtop LKC-1000S+ 0.91 to 0.92 3.1 to 3.6 Note, original model of Pro and Temtop LKC were tested, updated models used for our comparison testing. Why PM2.5 Matters PM2.5 are tiny particles that can reach deep into the lungs and even the bloodstream. When air pollution is talked about, it typically refers to levels of PM2.5, due to the serious health impacts. In New Zealand, indoor levels can often be higher than outdoors. Seeing the levels and changes in your home or workplace can help you decide if interventions such as ventilation or air purification is required.  What we tested   Models: Qingping Lite, Qingping Pro 2, Temtop M10i, Temtop M10+, Temtop S1+ and Temtop LKC-1000S+ 2nd. Environment: Same bench in an apartment (Christchurch), co-located and away from air vents. Period: 14 - 18 August 2025, hourly measurement results Objective: Check how closely the models track together in real conditions, using indepdently tested units as the benchmark Method and limitations Recording frequency: We aligned measurements to the unit with the lowest recording frequency (M10+), so all results are reported hourly.  Time adjustments: Not all units were recording exactly on the hour, so the closest recording to the hour was used. In some cases this was 5mins before or after the hour. Units plugged in: All units were plugged in to ensure regular readings and updating PM2.5 Exposure: Two spikes occured due to cooking with the frypan. No air cleaning was used, in order to keep levels high for longer. Results By the numbers Most pairs have correlations between 0.95 and 0.99, indicating very high levels of correlation Typical difference: Around ~1 µg/m³ when averaged over the period Mean reading: Small spread across devices, mean PM2.5 reading for the each device across the entire period was between 3.2 and 5.0 µg/m³. Variances observed during initial PM2.5 spikes, due to timing of readings. A note about PM10 One of the reasons we focus on PM2.5 is that PM10 numbers from low-cost optical sensors are generally less reliable than PM2.5. This is shown in the Southcoast AQMD results, where PM10 accuracies were always quite a bit lower than for PM2.5. This essentially boils down it it being more complex to measure for PM10 sized particles. If you'd like to learn more, there's a great writeup about this here.