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By 1 April 2019 April 2nd, 2019 No Comments

Ten years ago the AQM air quality station was born.

The AQM was unlike all other monitoring stations before it (and all since). Instead of analyzers, it used sensors, a technology that the industry did not trust.

The early years were tough. No one believed it would work and many wouldn’t even try. ‘If it’s not EPA/EU/TUV approved we won’t touch it’. The same message over and over.

But there was one little problem.

The AQM worked. It measured key air pollutants – especially particulate, ozone and nitrogen dioxide – well and provided people with accurate air quality information at a fraction of the price of traditional stations.

Because it was smaller and cheaper customers could extend their air monitoring networks and measure air quality where air quality had never before been measured.

In the ten years since the AQM was born the air quality industry has seen massive change too. This blog charts the evolution of the industry alongside the early years of our flagship product.


The roots of the AQM went back to Aeroqual’s founding in 2001. Founders Geoff Henshaw and David Williams wanted to measure air quality across a city at much greater density, so they could better understand how air quality varied across the urban landscape. They knew the air wasn’t as uniform as the official government stations were reporting.

Initially we made portable monitors for measuring ozone. They were used indoors and outdoors -and still are! Researchers started doing outdoor studies with them and getting fantastic results.

It wasn’t long before a customer asked if we could make a complete station that could measure all the pollutants of interest. The year was 2006.


Like everyone else that wants to make an air quality monitor, we started out by putting a bunch of sensors in a box, writing a bit of software and putting it out on the street.

Of course it didn’t work.

The sensors drifted like crazy. There was temperature and humidity interference. We had no way of checking if the readings were real or spurious. Servicing was a nightmare. Sensor life was nasty, brutish and short.


We learnt quickly from those early prototypes.

To validate the measurements we needed a way to calibrate the system in the lab and in the field. The solution was to introduce a manifold with a pumped inlet system so that the sensors would be calibrated using standard gases and a dilution calibrator – the exact same way that an EPA/EU approved analyzer is calibrated.

To deal with baseline noise and temperature and humidity interference we integrated a zero air source. Now we could switch between ‘zero’ and sampling states, giving the ability to do a zero calibration between every measurement cycle. This improved measurement certainty massively.

Customers told us they wanted to measure particulate matter at the same time. Being experts in gas sensors we went and talked to experts in particle measurement. So began our long association and partnership with Met One Instruments of Oregon, USA.

The whole system was made modular to make servicing easier. Sensors fail, it was true then and still is. So we made it easy to isolate the failed sensor and remove it without bringing down the rest of the system.

The resulting station performed much much better. We called it the AQM 60.


Early prototype AQM 60 modular system


It was 2008. We marketed the AQM to customers around the world through our existing distributor partnerships (built up on the back of the ever-popular portable ozone monitors). There were projects in UK, New Zealand, India, and Eastern Europe.

Most of them failed.

What we realised was that climate has a huge impact on the way sensors behave. If you are asking a relatively cheap sensor to measure pollutants at ambient concentrations (sometimes in the ppb range) you need to give the sensors the best possible chance of success.

Further tests back in the lab showed that sensors can operate at 5°C, and they can operate at 40°C. The problems start when the temperature changes, and the rate of change has the greatest effect.

In 2009 we introduced a thermo-cooled AQM using a peltier cooling system. We relied on the electronics inside the enclosure for heating, activating the cooling when things got too hot in the box. In this way were able to keep temperatures to +/-5°C.


In 2009 most customers interested in the AQM were in parts of the world without air quality monitoring networks. They wanted to measure the air, often obligated by law to measure and report air quality to their citizens.

They just didn’t have enough money for the traditional equipment.

We came along with the AQM and showed them a station that produced useful information at 5 x less cost than a traditional monitoring station. Now they could buy one or two AQMs and make a start on their air quality monitoring journey.

The AQM got its start thanks to those customers in less well-off countries without pre-existing air monitoring infrastructure (and without the fixed ideas that go with it). With open minds they imagined a future where air quality information could be ubiquitous.

We will always be grateful to them.


AQM 60 Air Quality Monitoring Station


In 2010, shortly after the global financial crisis, Dubai faced a period of massive uncertainty. Expats were fleeing the country, leaving their lease cars parked at the airport as they flew home in search of work.

At the same time Dubai was in the process of evaluating a way to extend their air monitoring network. They had some traditional air monitoring stations that had fallen into disrepair. The cost to replace the stations and cover the sprawling city was beyond the capacity of the public purse at that time.

Through our distributor in the region (special mention to Mr Herve Rouse for his role in the journey of the AQM) we were introduced to Dubai Municipality and started a conversation about another way of doing things.

A year later Dubai placed an order for delivery of 14 AQM compact air monitoring stations. It was to be the first city-wide air monitoring network built entirely on sensor technology. You can read more about it in this case study.


The Dubai project helped catalyse a raft of improvements. It would be hot and high profile and we absolutely had to deliver.

The thermo-cooler was replaced by a compressor-based cooling system, coupled with heating elements. We introduced better insulation and solar shields. This gave us the ability to control temperature to within +/-1°C which would be essential in the hot days and cold nights of the Gulf city.


16x AQM 60’s were installed in Dubai

The inlet system was switched around. Before this point sampling had been done at the base of the unit. In the ‘Dubai version’ the sampling inlet was switched to the top and we added an inert sampling cane.

We added a robust industrial modem and developed a remote data acquisition system. Being based in New Zealand, supporting projects all over the world, had taught us the value of being able to connect to and work on the instruments in real-time. We also made the system compatible with ENVIDAS, which was the software package preferred by the government of Dubai.

Our government customers had drummed into us the importance of traceability. Although the AQM could be field-calibrated, we had been having mixed results using off-the-shelf dilution calibrators. They had a tendency to produce dry air that was to the detriment of the sensors. This led us to develop our own calibration equipment – the AirCal 1000.

With unmatched sensor performance and the ability validate the sensors through true calibration – we started to talk about a set of technologies we call Near Reference.

Rather than rely on our own sensors for every gas measurement, we scoured the market for best of breed. Our proprietary GSS sensorswere retained for ozone, NO2 and NOx, but we selected electrochemical sensors for sulfur dioxide and carbon monoxide. A VOC module was created built on well-established PID sensor technology. As a company we’ve never been too proud to look outside if we felt that someone else’s technology could deliver a better solution for the customer.

What we are good at is making the whole greater than the sum of the parts.


After Dubai the industry found it increasingly difficult to write us off. We started to win projects in the U.S. and Europe. Sensor-based competitors started popping up all over the place – we welcomed it as a sign that finally we were getting somewhere.

Then in 2013 the U.S. Environmental Protection Agency came out with their Next Generation Air Monitoring Roadmap. This sentence in particular caught our eye:

Current sophisticated, expensive ambient air pollution monitoring technology is not economically sustainable as the sole approach and cannot keep up with current needs.

Something clicked.


Now that the AQM was becoming mainstream we decided it was time for a major upgrade.

The AQM 65 story has already been told in a previous blog, when it was launched. A quick summary of the changes:

  • Complete re-engineering of the enclosure, so much more than just a box
  • Upgrade of the thermal management system (now capable of +/-0.2°C)
  • Change of the SO2 and H2S modules to a new switching design that integrated a zero calibration into the modules themselves
  • Overhaul of the AQM controller and operating system (a browser based interface, Aeroqual Connect)
  • Addition of WIFI connection capability – now technicians can access the instrument without leaving the comfort of their car!
  • Introduction of a cloud-based data acquisition system, Aeroqual Cloud, which gave us and our customers unprecedented access to data and instrument settings from any device anywhere anytime.

AQM_Birthday_Post_4Customers seemed to like it. Sales doubled year on year. We won the top award for the Most Innovative Hardware product at the New Zealand High Tech Awards.


As you can tell we are mighty proud of the AQM and what it has achieved.

The Dubai network continues to operate 8 years on, there are more than 1,000 units in operation from the Gobi Desert to the streets of New York, and the product continues to get better with every new version.

We’re also proud to be part of an emergent industry dedicated to using sensor technology to better quantify air pollution’s impact on people. The AQM has played a founding role and continues to lead the way.

So last week, to celebrate, a few of us gathered round a cake, donned some stupid hats and all sang along…

Happy birthday to you, Happy birthday to you, Happy birth-day dear AQM, Happy birthday to you!


The Aeroqual team celebrating AQM’s 10th birthday with a few games of ten-pin bowling


Author Admin

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