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MerleGering Aug 25, 2020 04:31 PM
Where is the correct location to measure NO2 to determine whether or not the EU NO2 annual mean limit is being met?

I wish to understand the correct location, for monitoring NO2. Tech Report 11 suggests that kerbside is an appropriate location. In the UK, The Department for Environment (DEFRA), has moved the correct location further away from the road, to the building facade, (see box 1.1 of their LAQM Technical Guidance16 'TG16') - which will of course record much lower readings. Is this the right place to be monitoring, for correct implementation of the Air Quality Monitoring Directive and for assessing whether or not the annual mean NO2 limit is being breached?

the Directive , in Annex VI, instructs national authorities to monitor at points "where highest concentration occur" to which "the population is likely to be directly or indirectly exposed".
In my view, that means you should locate monitors (in this case diffusion tubes) at kerbside (since the directive explicitly excludes measurement in the road. that's where the highest concentrations will occur, and large numbers of people will be exposed at those levels (for example in the UK, there are 1.2 million professional drivers, who will at least get this exposure 8 hours a day, 5 days a week; then there are postmen, street cleaners, builders & engineers working in the roads works, waiters serving in streetside cafes, trash collectors, etc)

 I am a citizen scientist and campaigner in the UK. I am concerned that the true extent of the problem is being concealed by measuring NO2 in locations which artificially reduce the reported levels.
Replies (1)
EEA Aug 26, 2020 02:13 PM
Dear Ms. Merle Gering,

According to the European legislation on air quality, the criteria for the location of stations monitoring NO2 (among other pollutants) are defined in Annex III to Directive 2008/50/EC, modified by Directive (EU) 2015/1480.

What this annex says when it comes to traffic-oriented stations is, among others, the following:

In terms of macro-scaling:
- Sampling points directed at the protection of human health shall be sited in such a way as to provide data on the (…) areas within zones and agglomerations where the highest concentrations occur to which the population is likely to be directly or indirectly exposed
- Sampling points shall in general be sited in such a way as to avoid measuring very small micro-environments in their immediate vicinity, which means that a sampling point must be sited in such a way that the air sampled is representative of air quality for a street segment no less than 100 m length at traffic-orientated sites (…), where feasible;

In terms of micro-scaling, in so far as is practicable (…) :
- for all pollutants, traffic-orientated sampling probes shall be at least 25 m from the edge of major junctions and no more than 10 m from the kerbside. A ‘major junction’ to be considered here is a junction which interrupts the traffic flow and causes different emissions (stop&go) from the rest of the road.

Please note that the European environment legislation and its implementation is beyond the EEA's working remit. You can address queries on the above-mentioned directives and on locations of sampling points to the European Commission - DG Environment via its online service:

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EEA Enquiry Service