Opening up the path to better monitoring

Local authorities need quicker, more cost-effective integrated air quality monitoring. Duncan Mounsor explains how open path technology can help

For local authorities, ongoing air quality monitoring is a necessity. If the forthcoming London low emissions zone scheme heralds the results that many hope, more UK-based authorities will be looking for intelligent systems that they can fit and forget.

Having worked on air quality monitoring with LAs over the past 24 years, I have seen many changes when it comes to air quality analysis, monitoring and reporting. But there are a few issues that remain constant. These are operator time associated with the smooth running of stations, cost-effectiveness of different types of analysers, and complete system integration.

LAs want to integrate air quality systems in order to take the pressure off staff in terms of operational time. They want value-for-money systems that give them the best return. And, above all, they want complete system integration - monitoring instruments that can send data in real-time through broadband connections to both internal and external sources.

Seeking ways to save on time
LAs are constantly looking for ways to cut down on air quality analyser operator time. Stand-alone analysers measuring individual compounds are much less time efficient than one analyser that measures them all. Another reason operator time is higher using traditional analysers is the high number of internal components, which gives more opportunity for faults. And point method analysers need calibration about every two weeks, which causes another drain on both resources and budget. This is why councils are increasingly looking to newer technologies.

One such technology is open path measurement. This uses a transmitter and a receiver to measure compounds between a 100m to 500m distance, giving a more representative air quality measurement. The open path system works using a xenon light path to measure stated gases. Open path systems, such as Enviro Technology's OPSIS 300, use differential optical absorption spectroscopy to measure these gases.

A xenon lamp transmits visible light from the transmitter to the receiver, and gases such as NO2, SO2 and O3 absorb into the UV part of the light spectrum and are measured from there. This enables their concentrations to be calculated. Up to ten or more gases can be measured using the open path technique with just one analyser. The OPSIS 300 was the first ambient air quality monitoring system to receive MCERTS approval for the measurement of multiple gases.

Less maintenance required
Due to the nature of the open path measurement technique - systems such as OPSIS have fewer than five moving parts - maintenance and calibration take less time than traditional point analysers. Sampling takes place in the light path, and this again cuts down on the amount of time an operator needs to dedicate to the operation of the open path system. They are suitable for use in city canyon streets, roadside locations and urban background locations.

A study carried out by Enviro Technology showed that, over a ten-year period, LAs could save £150,000 using the open path technique compared with the point method. Although initial outlay was a little higher, there were significant cost savings in servicing, parts and operator time.

LAs want to access their air quality data wherever they are. They want faster data capture, lower data costs and be able to use other web technology such as webcams and digital chart recorders. Broadband technology has made data transfer faster, and many see internet-based data collection as the way forward.

In response to this Enviro Technology launched the ET DataWEB system. This system works with any available software that uses a communication port, as well as Hyperterminal, APICOM, ComVisioner or any other Enviro Technology supported software. It allows the customer, and a service provider, to connect to the remote station anywhere in the world, at no extra cost, with no time limits.

Remote diagnostics testing is also easier and twice as quick as traditional methods. A LA's IT department will also prefer this solution because they see a connection to an IP address as a far more secure method of data collection.

Duncan Mounsor is operations director at Enviro Technology

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