AQMesh performance

How good are measurements?

AQMesh has been in development, global trials and available for sale since 2013. During that time, AQMesh v.3.0 showed that trends could be identified and the product was suitable for a number of air quality applications. Developments at the end of 2014 – improvements in electrochemical sensors and the AQMesh processing algorithms – have given a dramatic improvement in performance with AQMesh v.4.0, v.4.1. and v.4.2. The process and benefits of sensor characterisation at manufacture include optimal correction for environmental factors, correction of gas span and baseline offset.

 

The most popular method for measuring AQMesh performance is by co-locating AQMesh pods immediately next to an air quality monitoring reference station and carrying out regression analysis of AQMesh readings against those from the RTMS, where a higher R2 shows a closer match in readings from the two types of equipment (an R2 value of 1.0 is a perfect relationship, and is unlikely to be achieved even by two co-located reference instruments; R2 of 0.0 would indicate no relationship at all between the instruments).

The table below shows that the R2 value achieved has shown a significant improvement from v.3.0 and v.4.2:

NO2

Version v3.0 v3.5 v4.0 v4.1 v4.2
Date To December 2014 January 2015 – October 2015 January 2015 – October 2016 Limited release October 2016 – present
NO2 sensor Significant O3 cross-gas effect O3-filtered O3-filtered O3-filtered O3-filtered and improved respoonse at higher ambient temperatures
NO2 sensor characterisation Manufacturer’s data Manufacturer’s data Manufacturer’s data plus characterisation at factory Quality check Quality check, accuracy and precision tests
Online processing Correction for cross-gas effects and environmental factors Correction for cross-gas effects and environmental factors Correction for cross-gas effects and environmental factors More sophisticated correction for cross-gas effects and environmental factors Optimised electronic set-up and performance enhancements below LOD
Typical R2 against reference in co-location trials* 0-0.3 0.1-0.7 0.5-0.8 0.7-0.95 >0.8
Typical pre-scaled mean variance* Requires scaling Requires scaling Requires scaling Dependent on variance between sensors <+/-5ppb

R2 of >0.6 for NO2 is generally considered to be a strong enough performance for AQMesh to be suitable for most air quality monitoring applications.

*Readings at 15 minute average intervals

A number of independent comparison studies have been published online – please note any date / AQMesh version against the table above to establish whether the study relates to the latest version.

Standard operating procedure

The standard operating procedure provides users with all the necessary information to get the best possible performance with AQMesh.

Read more on AQMesh performance

AQMesh case studies

Co-location comparison trial results

View current live demo of AQMesh vs reference

Latest AQMesh news

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The first v.4.0 pods are now being co-located with reference stations globally and further performance data will be published in the news section and co-location comparison trials as it becomes available.

AQMesh