Mon 29 Oct 2012 – Around 110 people in the UK die early each year due to lung cancer and cardiopulmonary diseases caused as a result of exposure to fine particulate matter (PM2.5) emissions from airports, finds a report released by the Massachusetts Institute of Technology (MIT). Even without airport capacity expansion, it estimates the number is projected to rise to 250 by 2030. With nearly half the early deaths being attributed to emissions from London Heathrow, a decision on whether to add a third runway at the hub or build a new airport east of London would significantly impact on the number of early deaths. The findings come as a fierce debate over capacity in the south-east of the UK continues with the owners of Gatwick Airport claiming a new second runway at the airport would have a lower environmental impact than an additional runway at Heathrow. The MIT report concludes that due to prevailing winds, a new hub in the Thames estuary makes better public health sense.
The research by MIT’s Laboratory for Aviation and the Environment was led by Dr Steven Barrett, who originally started the study when at the University of Cambridge as part of the Energy Efficient Cities Initiative. The peer-reviewed paper is due to be published in the UK-based scientific journal Atmospheric Environment.
The researchers based their findings on emissions from the top 20 UK airports by passenger numbers and computed using an approach based on aircraft engine certification measurements with corrections to account for operational factors. A base year of 2005 was used, with passenger and aircraft forecasts to 2030 from the UK Department for Transport. New aircraft entering the fleet were considered, including anticipated changes in environmental performance for newer aircraft.
The study looks at three future scenarios: constrained UK capacity growth in which no airport expansion takes place but increased airport utilisation results in increasing emissions, and unconstrained growth from either a third new runway at Heathrow or a new Thames estuary hub airport is built and Heathrow is closed.
Under the first scenario, the increase from the present 110 early deaths caused by airport pollution to 250 by 2030 will be as a result of the additional traffic growth but also due to a growing and therefore more exposed population, an ageing population more susceptible to air quality-related diseases and, paradoxically, as the atmosphere is projected to be cleaner in the future, the incremental impact of aircraft emissions is projected to be greater. Simply put, one tonne of pollution into a clean atmosphere causes a greater impact than emitting it into an already polluted atmosphere.
Of the 250 early deaths in 2030, about 110 are likely to be due to emissions from Heathrow. If a third runway is built, the number rises to 150, although this is compensated for by reductions at other London airports on the basis that some air traffic would move away to the enlarged Heathrow, so that nationwide there are about 10 additional early deaths per year.
However, if the UK hub airport is moved to the Thames estuary, the health impacts are reduced by 60-70% to about 50 early deaths.
“The results imply that the public health impacts of Heathrow will triple by 2030 if it is expanded, or double if it is not expanded,” Barrett told GreenAir. “In comparison, a replacement in the Thames estuary would reduce the air quality impacts to about their present level notwithstanding capacity expansion. This is because much of the pollution from a Thames hub airport would blow out to sea, given the prevailing winds.”
Situated west of London with prevailing south-westerly winds, Heathrow is upwind of a major chunk of London’s population, whereas the wind would carry most of the pollution from a hub to the east of London out towards the North Sea.
Barrett suggests the aviation industry could adopt a number of near-term and relatively low cost mitigation measures that would alleviate the number of early deaths. The removal of sulphur from jet fuel would avert 20 early deaths per year and, which will be welcome news to the alternative fuels sector, the use of biomass-derived fuels could save up to 50 early deaths annually.
Other measures that could have a positive impact include single engine taxiing (saving up to 10 early deaths per year), the electrification of ground support equipment (up to 30 early deaths) and the avoidance of the use of aircraft auxiliary power units (up to 10 early deaths).
Barrett said he accepted that single engine taxiing and APU avoidance measures were already being implemented but his researchers found it difficult to determine the exact extent and often it was at the pilot’s discretion.
However, a collaboration between the UK aviation industry and the Department for Transport will see these concerns addressed by a new voluntary code of practice intended to reduce the environmental impacts from ground operations and departing aircraft at UK airports. Single-engine taxiing and reduced use of APUs are two of the four key initiatives defined in the Departures & Ground Operations Code of Practice launched in June (see article).
The impact of road traffic to and from airports was not taken into consideration for the study. “It could be argued that this would either increase or decrease the relative benefit of a Thames hub compared with Heathrow expansion,” he said. “For example, the Thames hub would be further away, therefore more emissions if people travelled by car to it, but such emissions would be downwind of London and further away from the middle of London so there would be less damage. Also, proponents of the Thames hub argue that a new efficient high-speed rail link could be constructed to the airport, perhaps taking a spur line off the HS1 Channel rail link.”
Compared to other forms of transport, early deaths from aviation-related PM2.5 air pollution is small. Another study conducted by Barrett and his team published earlier this year found that some 3,300 people per year in the UK met premature deaths from car and truck exhaust emissions, out of a total of 13,000 overall from all forms of transport and powerplant emissions (see report).
“It’s important to keep in mind that although aviation is a relatively small contributor to air quality degradation and emissions in general, it is growing relatively quickly,” warns Barrett.
Another study carried out by MIT and published in 2010 found that around 8,000 premature deaths per year can be attributed to the effects of oxides of nitrogen and sulphur (NOx and SOx) emissions from aircraft at cruise altitude (see article). These emissions emanate over North America and Europe but the prevailing westerly winds take them eastwards and nearly half the early deaths occur in India and China. With an even greater health impact, emissions from shipping are believed to be responsible for around 60,000 premature deaths annually, although the industry is making efforts to reduce sulphur levels in fuels and the EU is about to phase in tough new limits.
MIT Laboratory for Aviation and the Environment – UK airport air quality report summary (3mb PDF)
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