Tuesday, 20 May 2008

Nitrogen, Oxygen, Carbon Dioxide... Air, to you and me

At the Village Society meeting last week, a lady asked me about air quality in Wrecclesham. It reminded me that we had some air quality measurement going on in Wrecclesham, that I first heard about a year ago. So, I did some follow-up.

However, (and I'm learning as I go here from Anne Sayer, all things air quality at Waverley), it's not a simple matter of taking a year's readings and then extrapolating conclusions. Things such as temperature, precipitation (rain, to you and me), and wind, all contribute to the quality of air, and with these things ranging widely in quality over different years, comparative analysis is complex.

To quote Anne:
Diffusion tubes are a cost effective method of monitoring Nitrogen Dioxide levels.

Data for each month is then averaged over the year to show whether the Government's annual maximum objective for Nitrogen Dioxide is being exceeded. This objective allows a maximum level of 40 micrograms of nitrogen dioxide per cubic metre - if this is exceeded then the local authority must undertake a more detailed assessment.Areas of exposures are areas where people are expected to spend time - for this objective they include the boundaries of people's houses (but not their gardens) and public offices etc.

Waverley produces an annual report on air quality for the Government every year. This report concluded that the objective for nitrogen dioxide was not exceeded at the Wrecclesham monitoring site in 2007 - the first full year of data (although it was only just below) so we are not recommending a more detailed assessment at this point.

I'm now a little bit more educated thanks to Anne, but certainly not an expert in this area yet. Do let me know if you think it should be investigated a bit more - especially if you're offering to do the investigation yourself!

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