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Until now we have referred to Aeroqual’s sensor technology as “Near Reference” but with the development of a new specific NO2 sensor combined with the AQS1’s reference flow technology we are now seeing data, from this tiny box, of the accuracy you would expect from a reference (MCERTS) analyser. This will allow you to get accurate data from confined spaces for NO2, Ozone, PM1, PM2.5, PM10 and TSP. Aeroqual’s unique technology means it can be calibrated directly from calibration gas on site for full QA/QC. LSO (site visits) are only required every 3-6 months so reducing operation costs and saving time. The simplicity of operation of this system further reduces operation costs and improves reliability and data capture rates. This is shown by the study below.

Comparison of AQS1 vs Reference NO2 over 3 Months:

From April to July 2020 an AQS1 was operated close to our reference chemiluminescent NOx analyser (see figure 1). Neither instrument was adjusted during this period, so it has not been possible to apportion drift between the two instruments. However, the data does show just how closely the two analysers tracked each other over a period of more than three months without calibration or adjustment.

The graphs below show how closely the two instruments agreed over three months for when peaks in levels occurred near to the beginning and end of the trial.

Three Month Regression Plots of Hourly Mean Values

The regression plots below show how the AQS1 agreed with the Reference analysers over the three months of the trial. Nitrogen Dioxide levels were unusually low during this period resulting in a lower R2 value for NO2 but correlation at the 40ug/m3 annual limit was excellent. Ozone levels were much higher at times and shows even better correlation, although this is mainly due to Aeroqual’s unique ozone measurement technology.

Time Series Plots and Data Capture

The reference NOx analyser was offline on 17th and 18th June due to a fault. A further failure occurred on 27th and 28th July. The trial was curtailed when both reference analysers were taken away for repair. The AQS1 showed no faults during the three months and is still in operation on 14th September. Data capture for the AQS1 was 100%.


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