Air pollution from airports revealed by volcanic ash cloud

Date added: 18 June, 2010

17.6.2010 (Aviation Environment Federation)

As well as the direct benefits to residents, who had days of unaccustomed peace
from aircraft noise, there was an indirect environmental benefit from volcanic
ash cloud. 

The cessation of flights at major airports allowed scientists to confirm that
airports are significant causes of air pollution.  

Because the pollutants produced by aircraft and airport operations are largely
the same as those produced by other sources, such as roads and buildings, it is
not normally possible to measure the proportion of total concentrations of pollutants
coming from the airport.   (The proportion has to be estimated by complex computer
simulations.)  

Ben Barratt and Gary Fuller of the Environmental Research Group at King’s College,
London carried out a study using air pollution data before and during the closure
of Gatwick and Heathrow airports.

In outline, what the researchers did was to find two air pollution monitors,
one upwind and one downwind of the airport during the closure. When the airport
was working normally, the downwind monitor would record the pollution from the
airport while the upwind monitor would not.   But when the airport was closed,
there would be no pollution from the airport at either monitor. By subtracting
results, the researchers could calculate pollution caused by the airport and its
planes.              

Ben Barratt and Gary Fuller said "This period of unprecedented closure during unexceptional weather conditions
has allowed us to demonstrate that the airports have a clear measurable effect on NO2 [nitrogen dioxide] 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."

"We have always been fairly confident that there was this ‘airport effect’ but
we have never been able to show it," Dr Barratt added  "The closure gave us the opportunity to look at it, and there is a very strong
indication that it is the case."

At Gatwick, the concentrations of NO2 due to the airport at the monitoring point
SW of the airport dropped from an average of 8ug/m-3 (microgrammes per cubic metre)
to zero when the airport was closed.   This would correspond to a drop in the annual
average of pollution from all sources from about 18 to 16 ug/m-3. (The drop in
annual average is much less because the monitor SW of the airport is only downwind
for a smallish proportion of a year.)        

At Heathrow, the concentrations of NO2 due to the airport  at the monitoring point
SW of  to the airport dropped from an average of 19ug/m-3 to zero when the airport
was closed.   This would correspond to a drop in the annual average of pollution
from all sources from about 33 to 30 ug/m-3 at point just SW of the airport.    

For more information see short report  (pdf, 4pp).   http://www.aef.org.uk/uploads/AirPollVol.pdf

(if link does not work, cut and paste it into your browser, rather than clicking
on it)

It ends:

This exceptional closure has allowed us to demonstrate the impacts of airport
emissions on their immediate neighbourhood. The evidence from this preliminary
analysis can be extended to quantify the impacts of Gatwick and Heathrow airport
on their neighbourhoods during normal operation.

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 additional analysis at
this time.

Ben Barratt and Gary Fuller

King’s College London Environmental Research Group

Posted: Friday, June 18th, 2010. Filed in General News.