Environmental Engineering Reference
In-Depth Information
at different points in the cycle. Take-off has the highest emissions of NO
x
with low
emissions of NMVOCs and CO, while landing has higher emissions of NMVOCs
and CO. Other emissions arise from fuel handling (evaporative losses and spillages)
and operation of auxiliary power units.
Road traffic
Road traffic sources include emissions from airport access traffic, construction traf-
fic, car parks, filling stations and air-side vehicles) For example, at any one time
Heathrow Airport may have up to 350 diesel taxis waiting, the highest number of
taxis waiting on a single site in the UK.
Other sources
Other sources include airport combustion plants (boiler houses), simulated fire exer-
cises and paint shops, and other transport infrastructure (eg railway operations).
Emissions from aircraft are only considered to impact upon the local environ-
ment during the LTO cycle, which is normally treated as those operations at which
the aircraft is below the atmospheric boundary layer (approximately 1000m height,
although variable). Therefore, exposure in the general population can vary depend-
ing upon the direction of take-off and landing.
In common with the majority of air quality health studies, the main air-pollution-
related health concerns that have been investigated around airports are respiratory
complaints (eg chronic obstructive pulmonary disease, asthma, etc). Investigations
into a broader range of health problems such as angina, bronchitis, anxiety and
depression have been reported but have not demonstrated an association with living
in the flight path area (Harrison et al, 2000).
Elevated concentrations of NO
x
, SO
2
, O
3
, NMVOCs and PM
10
have all been
closely associated with respiratory-related admissions to hospital and mortality
(COMEAP, 1998). However, a number of medical studies, such as hospital admis-
sion epidemiology, population health studies, measures of lung function and other
questionnaire surveys, at airports such as Birmingham International, Schiphol and
Heathrow have yet to show any evidence that airport operations are causing any
additional respiratory effect that could not be explained by differences in lifestyle
(Harrison et al, 2000; Franssen et al, 1999; Hillingdon Health Authority, 1997). An
occupational study of airport workers who were more directly exposed to aviation
fuels and jet exhaust did report an association with respiratory symptoms, although
the authors could not draw strong conclusions as to the specific cause (Tunnicliffe at
al, 1999).
Despite public concerns regarding the levels of NMVOCs and their cancer-
causing properties, there have been few studies of cancer amongst the general popu-
lation around airports. Studies have only shown slight elevations in certain types of
cancer that, due to differences in lifestyle, such as smoking habits, cannot demon-
strate an association between air traffic and increased cancer risk (Visser et al, 1997).
Occupational studies amongst airport personnel have shown low exposure to
hydrocarbons and jet fuel derivatives, and while concentrations were typically under
occupational exposure limits, the use of respirators amongst highly exposed workers
