HACAN newsletter April 2010

Dear All,

In this Update:

Election News
The latest from the court case
Air Pollution levels fall during the plane-free days
New Economic Report on Heathrow

John Stewart

johnstewart2@btconnect.com

Election News

Check out our website – www.hacan.org.uk – for information on what the party manifestos say on Heathrow. We are also putting up news of election “hustings” meetings as we get them. Email me with details of any you may think relevant – johnstewart2@btconnect.com

Court Case Costs

Lord Justice Carnwarth confirmed in a short follow up court hearing to apportion costs on 20th April that the campaigners against Heathrow expansion scored a significant win in the High Court. He said “Frankly you are entitled to say you have won substantially.” He ordered the Department for Transport to pay their own costs plus 60% of the opponents’ costs.

Air Pollution Down During Plane-Free Days

Research from the London Air Quality Network at Kings College London has shown the air pollution levels around Gatwick and Heathrow fell significantly during the plane-free days.


The impact of airport closures on local air quality.

We have received many enquiries asking what the effects of the closure of UK airspace has had on air quality surrounding major airports. In response we have made an initial analysis of NOX and NO2 concentrations surrounding Gatwick and Heathrow airports during the first three days of closure – Thursday 15th to Saturday 17th April 2010. This period was chosen due to the stable weather conditions with light north easterly winds, allowing a cross-sectional analysis upwind and downwind of the airports.

This period of unprecedented closure during unexceptional weather conditions has allowed us to demonstrate that the airports have a clear measurable effect on NO2 concentrations and that this effect disappeared entirely during the period of closure, leading to a temporary but significant fall in pollutant concentrations adjacent to the airport perimeters.

Concentrations recorded by a monitoring site arise from a mix of pollution sources both local and distant affecting that specific location. In order to separate and quantify the affects of a particular local source, such as emissions from an airport, a control dataset is required. In this case pairs of monitoring sites were used located either side of each airport. The upwind monitors provided the control data. By subtracting hourly mean concentrations recorded by the upwind site from those recorded by the downwind site, an estimation of emissions from the airport could be made – termed ‘airport’ concentrations. The figure above shows daily diurnal mean ‘airport’ NOX concentrations for the ‘open’ and ‘closed’ periods at a monitoring site close to the perimeter of Gatwick airport. The yellow shaded areas indicate hours where winds were from the north or north east during the closure period, i.e., the site was downwind of the airport runway. The chart shows that during normal operating conditions ‘airport’ NOX concentrations increase during the day peaking at around 22 to 25 µg m-3 on average. During the period of closure (15th to 17th April 2010) mean ‘airport’ NOX concentrations were zero most of the time. All concentrations were well below the lower 95% confidence interval indicating that the difference from ‘normal’ operation was statistically significant.

The analysis was repeated for NO2, with similar results. The annual mean NO2 concentration measured at this location (‘RG3’), to the south west of the airport, during 2009 would decrease from 18 µg m-3 to approximately 16 µg m-3 in the absence of airport emissions. The impact of the airport is likely to be greater in the populated areas to the north east of the airport (Horley) due to prevailing winds from the south west.

A similar analysis was carried out using a pair of monitoring sites surrounding Heathrow airport. ‘Airport’ NO2 concentrations were higher those at Gatwick and dropped from 27 µg m-3 to 8 µg m-3 during the closure period.
This exceptional closure has allowed us to demonstrate the impacts of airport emissions on their immediate neighbourhood. This preliminary study did not consider the impact of decreased traffic flows on airport feeder roads. Decreased flows are likely to have a significant effect on concentrations of vehicle-related pollutants close to such roads. Unfortunately, we do not have sufficient traffic data to carry out this analysis at this time.

A full version of the report is available for download using the link below.

More Information http://www.londonair.org.uk/london/reports/airportclosure_20042010.pdf