Agenda item

Members: Please note that copies of the draft Air Quality Action Plan are available in the Members’ Library.

Reference was made to article 39 of the minute of its previous meeting, when the Committee were presented with the draft Air Quality Action Plan, and whereby the Committee questioned officers extensively on the report and requested that officers report back and address the following issues: (1)  whether the sensors on Market Street could be moved to better reflect the air quality issues; (2)  if mobile sensors could be installed if the sensors in place could not be moved; (3)  if the salt in the air had been taken into consideration; and (4)  could the sources of pollution be better identified on Market Street, taking into consideration the fumes from boats in the harbour. It was further suggested that due to the resources that would be required to implement the Plan, that the report may have to be referred to the Finance and Resources Committee for their consideration. The Committee now had before it a report by the Director of Housing and Environment which sought to address these issues.

With reference to the questions raised in relation to air quality monitoring, the report advised that national guidance prescribed the type of equipment that should be utilised to monitor air quality, and locations where monitoring should be carried out.  As the air quality objectives were health based, monitoring was carried out at locations of relevant population exposure for the specific pollutants of concern (nitrogen dioxide (NO2) and particles (PM10)) in Aberdeen. Where a risk of exceedance of an objective was identified through the Local Air Quality Management (LAQM) process, authorities should monitor in these areas using approved continuous monitoring equipment such as the 6 stations throughout Aberdeen. The report explained that these stations were audited every 6 months and the data was checked daily and ratified by external agents who were appointed by the Scottish Government.  The selection of a site was determined by various criteria including population exposure, risk of exceedances of objectives, traffic flows, pavement width, proximity to major junctions, bus stops and other pollution sources.

The report continued that indicative levels of NO2 were also measured through diffusion tubes attached to lamp posts and downpipes at approximately 40 locations across Aberdeen.  These measurements were used to monitor trends and identify locations of potential exceedances.  There were 20 sites in the city centre and almost all exceeded the annual mean objective.  Maximum levels were on Market Street (70-80ugm^-3), Union Street close to the Holburn Street junction (60-70ugm^-3) and on parts of King Street (70ugm^-3).

The report advised that it was not possible to measure PM10 concentrations through diffusion tubes.  While other semi portable systems were available, costs were approximately £6,300 (compared to less than £10 for diffusion tubes), they required a power supply, and may be subject to vandalism, for example if attached to lamp posts in parts of the city.  Continuous monitoring through the existing stations had been considered the most appropriate measurement technique for PM10 monitoring.

In relation to the questions raised at the last meeting regarding emissions from ships in the harbour, the report highlighted that monitoring measures the total concentration of a pollutant at a specific location, and it was not possible to distinguish the contribution from different sources such as traffic, shipping or industrial sources. 

The consultant Cordah had been contracted to model emissions from the harbour in 2004 and this modelling had predicted that shipping accounted for annual mean NO2 and PM10 concentrations of 3-10ugm^-3 and 1-1.5ugm^-3 respectively.  Emissions may have been over estimated due to a number of worst case assumptions.  Prior to the commencement of construction works associated with the Union Square development, the annual mean NO2 and PM10 concentrations at the continuous monitoring station on Market Street were 50-60ugm^-3 and 51-52ugm^-3 respectively. It was concluded that emissions from shipping contributed to exceedances of the annual mean objectives, however traffic was the main source of the raised levels.

The report further advised members that in 2004, Aberdeen Harbour Board had commissioned Aberdeen University to carry out a study of the impact of harbour activities on air quality.  The study concluded that the harbour was not a major contributor to city centre pollution levels.  Monitoring of NO2 showed a significant gradient of low levels at the harbour mouth to high levels at the Market Street area.  An NO2 monitoring exercise by the environmental health service from 2005-2008 similarly showed lower levels at the harbour mouth away from road traffic and harbour internal activities such as the loading of cargo, with highest levels close to Market Street.

The report continued that the Technical Guidance document described the pollution sources, and processes that authorities must consider when undertaking annual air quality assessment reports, including occasions when specific sources such as airports, railway and bus stations, shipping and industrial sources must be considered in detail.  Using the criteria within the guidance, which considered the size, type and number of vessel movements, exceedance of the air quality objectives would not be predicted at Aberdeen Harbour and therefore no detailed assessment was required. The guidance also considered emissions of sulphur dioxide (SO2) to be the main pollutant of concern associated with shipping.  Both the Cordah modelling and the Aberdeen University study confirmed SO2 emissions associated with the vessel movements in Aberdeen were well below objective levels.

Emissions from vessels were controlled by European Union legislation specifying the fuel composition, and there were therefore limited actions the authority could take to reduce emissions.  The report concluded that the draft Air Quality Action Plan recognised that shipping and activities at the harbour did contribute to air pollution within the city centre, and included a measure to consider initiatives to improve air quality in the harbour area.

Copies of the draft Air Quality Action Plan, which had not been amended since the aforementioned meeting of the Committee, had been made available in the Members’ Library.

Members intimated their concern that the impact the harbour had on monitored emissions could not be quantified; and that decisions could be taken based on inaccurate information in this regard, and therefore the wrong areas of the city could become the focus of the Plan. 

The Committee resolved:-

(i)         to note the information regarding emissions from Aberdeen Harbour and the monitoring of air quality, including Market Street contained within the report;

(ii)        to approve the draft Air Quality Action Plan for public consultation and   submission to the Scottish Government;

(iii)       to instruct the Director of Housing and Environment to prepare a final Air Quality Action Plan for Committee consideration following the completion of the consultation; and

(iv)       to refer the report to the Enterprise, Planning and Infrastructure Committee for information due to the links between air quality, transport and planning.