It had been the case up until very recently that the only way to monitor the air was using reference monitoring equipment, normally house in large steel containers. This is still the case. For those organisations who are required to report as part of the AURN(automated urban and rural network) then large reference analysers which are regularly maintained and calibrated is now the case.
However,what if you needed to to have some kind of indication as to how they air changed within your location and that it was reasonably accurate.
This is where the indicative monitoring market become useful.
Indicative monitors tend to use low cell technology as well as low cost laser, Ir and pid technology.
what can they measure. (I will tell you a bit more about these pollutants and where they come from later)
PM10, PM 2.5 and PM1
CO- Carbon Monoxide
CO2- Carbon Dioxide
SO2- Sulphur Dioxide
They are now in an affordable range to the person in the street,
What do we mean by affordable and how good is an affordable unit?
This is where a bit of a minefield opens up. There are many many variants of product on the internet. Having worked with major consultants and the HSE it is now quite apparent which products are useful
Quality vs Quantity
The products we use and test tend to fall within the price range of £3,000 to £6,000. The price will vary from unit to unit depending on how it is configured. A unit that can monitor one gas and particulate matter only would be at the lower end of the price spectrum as compared with a four gas and particulate unit.
My words of cautious are :
1,beware purchasing any product for a specialist project that isnt sold by a company who is conversant with monitoring for pollutants
2, Many low cost units do not measure the parameters they state the will measure. For instance we compared a budget £400 product with a £5,000 product and introduce test gases into the budget product and the higher priced unit. The higher priced unit showed good correlation with the test gas. The budget one – did not register
How might you use your date? when you look at many government sites, it some becomes apparent that the data for different species are averaged according to different requirements. So it is important to understand how your going to average it.
Finally and very importantly – why are you doing this work? if it is important, we would recommend that you work with your regulating authority and establish with them a firm objective of what you are trying to do . This is difficult. they may have another political agenda.
What other features may be important:
A Data Dashboard – This often requires a yearly subscription to the company that hosts your data.
The data dashboard should show time based trends including peaks and averages. it should allow you to down load data into a spreadsheet.
Status: Information of the unit will be provided by the supporting company, whether the unit is online or if it has a fault
Particulate Matter : Two types of sampling are currently available : Analysers with heated head inlets and those without. The ones without require a very specific algorithm in order to ensure that moisture droplets are not counted as particulate. In order for this to occur the temperature and humidity of the sample also needs to be measures separately
GPS To enable the location of the unit to be shown on Google maps or similar
Wifi To acquire data that you can see on the data dashboard , the instrument has to communicate via wifi. You will need to ensure that you know what company supplies the best wifi coverage in your area for 4G. You will need to supply a SIMcard for this, we normally install this on your behalf
Power The units can typically be powered from a 7-24vdc source, 110v ac or 240V. It is always recommend that a circuit breaker be used. There is also a solar kit, which requires a large lead acid battery to be used with it. This is good for sunny climates
Installation Most of our units are supplied with a post/wall mounting kit. It typically takes 30mins to get up and running
Servicing & Cell Replacment
This typically occurs every 2 years sometimes longer depending on the environment the monitors have been in and the status of the cells/laser
Examples of Monitoring Diesel Vehicals
Roadside Monitoring or vehicle emissions. The most basic form of monitoring would be the requirement to monitor particulate, However not just the total Inhalable particulate. We also are required to monitor the fine particulate, the smaller sized 2.5 micron (pm2.5) and less. This is respirable dust and very harmful
As well particulate other gases which are associated with diesel engined vehicles are NO2 (Nitrogen Dioxide) and NO(Nitric Oxide)
we are currently in the process of finalising the development of a two gas and dust sampler for this specific application
Where Next : Once you have acquired data, you might wish to compare to national standard or european standards. Please note these are indicative levels not reference levels, but they are good to be used as to highlight an area of concern
I hope this brief guide has helped
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