What is Nitrogen Dioxide?

King’s College London along with other universities in London provides data and monitoring of air quality in London for the Mayor of London office and Local Authorities. Their website provides comprehensive data and information on air quality in London.

This is an extract from their site.

“Nitrogen dioxide (NO2) is one of a group of gases called nitrogen oxides. Road transport is estimated to be responsible for about 50% of total emissions of nitrogen oxides, which means that nitrogen dioxide levels are highest close to busy roads and in large urban areas. Gas boilers in buildings are also a source of nitrogen oxides.

There is good evidence that nitrogen is harmful to health. The most common outcomes are respiratory symptoms such as shortness of breath and cough. Nitrogen dioxide inflames the lining of the lung and reduces immunity to lung infections such as bronchitis. Studies also suggest that the health effects are more pronounced in people with asthma compared to healthy individuals.”

A simple test?

To get a good sample of the amount of NO2 in the air all you need is a test tube, some gauze and a bit of patience. The gauze is a little more complex than you would get in Boots and is designed to filter out certain gases in the air. The tubes are fixed to a lamp-post or nearby drainpipes where they must stay for at least one month to get a proper reading. Sometimes they are placed on houses or on balconies to get an idea of the levels of NO2 away from the road.  Caution has to be taken because of household NO2 coming from domestic boilers and the like.

A picture of a diffusion tube is shown right. Itdiffusion-tube’s about 2 inches high and is clamped to a lamp-post or drain pipe.

The little tubes are then take to a laboratory for chemical tests to see how much NO2 has been captured.

HS2, the Borough Council and the local community. What they did. 

In 2015 HS2 published their forecasts of what Nitrogen Dioxide levels in the air around Euston would be in 2017. The forecasts were based on Government numbers from 2013. They used computer modelling to predict current levels based on 2013 figures. The modelling method is approved by the Government and European Union agencies. Over the past year they have been backing this up with real readings around Euston.

Last year 2016 The London Borough of Camden put their tubes out across the Euston area. They had them up for 5 months and presented their results in October/November last year.

At the same time local residents, associations and traders groups got together with the local University in Gower Street (UCL) to get their own data for the Euston area. They had their tubes up for a month during October last year with the results analysed by UCL.

HS2 had more tubes up between June and December 2016.

The Data So Far

The map below shows the results so far of the monitoring of NO2 levels on the Regent’s Park Estate done by these three groups, HS2, Camden Council and the local community.

The HS2 black on white background numbers are projections from 2013 data. The white on blue background are the more recent real data from their monitoring tubes. The Camden Council and local Euston communities data is also real data from monitoring tubes.

RPE NO2 Levels

The green circles are the community -one month- readings. These were distributed not just by the roadside but in the gardens and squares on the estate. The reason here was to see just how the level of NO2 falls away from the main roads. At the junction of Stanhope Street and Robert Street the HS2 forecast was for 50.1 micro-grammes of NO2 per unit. Camden Council had a live test tube at this location for 5 months and this read over 60 micro-grammes.  The community tube further away in Clarence Gardens and Cumberland Market gave readings below 40 micro-grammes. There is a problem with just one months readings and they are prone to underestimating the annual average. The reading by Netley Street in Hampstead Road for example is almost 70 for the 5 months of Camden’s tube but below 50 for the one month of the community tube.

As with all statistics it is best to look at all the numbers and take an average view. In the case of the estate the levels of NO2 appear to be highest along the main roads, and well above the legal limit of 40 micro-grammes . On the minor roads and in the gardens they appear to be at or just below the legal limit.

To find out more about pollutants from traffic and how it is monitored click here to read a Government Sponsored pamphlet. AIR QUALITY EXPERT GROUP – Nitrogen Dioxide in
the United Kingdom.