Whilst some manufacturers use a calculation to give an NO2 reading, AQMesh uses a unique O3-filtered NO2 sensor for accurate, direct measurement of NO2.
It is true in general that small sensor system air quality system customers should be on a sharp look-out for “inferred” measurements, as opposed to direct measurements, because there is a lot of it about. Specifically regarding NO2 measurement, the cross-interference from O3 is well known and indeed was a limiting factor in the use of electrochemical sensors in the early stages of AQMesh development. The latest electrochemical sensor used to measure NO2 in AQMesh feature a filter to remove O3 from the air sample at the sensor interface and is highly effective, over at least the two-year recommended sensor life. In theory the filter can be exhausted during use but the levels of O3 which would be necessary to do this fall far short of the typical exposure that any sensor is likely to have in years of real-world measurement.
As well as delivering a reliable two-year NO2 sensor life, the O3 filter offers proven performance over this period, with no measurable degradation of performance or “drift”.