Improving air quality in Winchester

This has been and remains a major campaign for us.  Air pollution in Winchester has been a significant cause for concern.  Winchester City Council has been taking air quality measurements since 2003, when exceedances of EU Directive thresholds in both PM10 particulates (i.e. soot) and NO2 gas necessitated the declaration of an Air Quality Management Area (AQMA). 

The street pattern in central Winchester is essentially mediæval.  Because the narrow streets make it difficult to accommodate higher traffic levels, the local authority many years ago opted for one-way systems, rather than seek to limit the amount of traffic in the City centre.  The one-way circulatory system essentially results in significantly more vehicle-km within the city centre than would be the case with simple in-out radial access.  The main (as distinct from background) all-year monitoring station is in a busy part of the centre, by St George’s Street.  Diffusion tubes distributed around the town are also regularly monitored. 

There may be geographical factors of importance here, because this area lies essentially in the main river valley of Winchester, with significant uphill gradients of downland immediately to the east of and a long upward gradient to the west.  Diffusion tube results, however, do also indicate other areas of concern besides the city centre, even on higher ground to the west (Romsey Road). 

Winchester is a largely bypassed town and is not or need not be affected by significant through traffic.  Air pollution in Winchester is not imposed by matters beyond the control of local authorities (Winchester City District Council and Hampshire County Council); traffic in Winchester is of the authorities’ own making.

European Complaint:  Winchester branches of FoE and the Green Party are joint complainants under the provisions of the EC Ambient Air Quality Directive (Annex XI) for mean annual NO2 concentrations, for persistent failure to take action to meet the strictures of the Directive.  We submitted the complaint in November 2012 and it was accepted for consideration in February 2013 and in December 2013 we were told that the Commission would be amalgamating it with others in the SE region of the UK.  In ???? the Commission indicated that it was starting formal prosecution of the UK Government.   The UK Environment Department, DEFRA, informed local authorities, including Winchester District Council, that if it were subject to infraction fines (which can extend to €300M per annum), it would expect to pass those fines down to those local authorities that it considered had the power to affect the pollution levels in their areas. 

Since making our complaint the local authorities, far from taking any action towards meeting their obligations, have been taking more and more measures in the direction of increasing road traffic through the most affected areas.

 Scale of problem: Winchester fails to meet the annual mean NO2 target in the centre of Winchester (and spot measurements elsewhere, e.g. on Romsey Road, also indicate a likely problem with this measure).  It appears that this is not a target that will be reachable merely with the passing of time, through car technology improvement (as PM10  appears to have been).


NO2 Graph

Even if the PM10 levels are below the required threshold, they are not declining and remain high enough to be computable as health risks.  Quantification of health effects is hard to come by in unambiguous form.   In a study cited by the DoH  a quantitative life expectancy change is computed for PM2.5 and compared with other risks, specifically motor vehicle accidents and passive smoking.


The most recent data for Winchester (2012) of 31µgm-3 would imply a reduction in life expectancy of more than 1½ years.  Not many people in Winchester will be subject to this level of pollution all the time (fall-off is rapid away from road edges), but this ought to be a warning that we do not take particulate pollution seriously enough.

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