Environmental Engineering Reference
In-Depth Information
•
Maximum-efficiency air filters should be installed and properly maintained on
all aircraft and ground delays kept to a minimum.
•
Anyone with infectious TB should postpone travel until they become non-infec-
tious. However, boarding can and should be denied to individuals known to
have infectious TB.
Air travel does not seem to carry greater risk of infection with exposure to poten-
tially infectious tuberculosis than other modes of transport; however, it is important
that airlines follow the WHO guidelines in order to ensure that the transmission of
disease is kept to a minimum.
F
LIGHT
CREWS
Occupationally, cockpit crews (and frequent flyers) are exposed to elevated levels of
cosmic radiation, electromagnetic fields, sound, vibration, chemical substances, dry
air, and viral/infective particles during flight operations. They also operate in condi-
tions of mild hypoxia and circadian dysrhythmia. Work stress levels amongst cabin
staff are high and have been strongly implicated in complaints about workplace
(cabin) air quality.
Aircrew exposure to cosmic radiation
One of the most studied of the in-flight environmental parameters is the effect of cos-
mic radiation on aircrew. A common concern amongst aircrews is that the increasing
total accumulated dose over time might be expected to cause an increased frequency
of radiation-induced cancer. If this is the case, the cancer rate should increase with
cumulative radiation exposure (ie number of flight hours per year, number of years
of flying and higher flight altitude). It is believed that crew members who fly jets may
receive a dose that is four to five times the average background radiation dose. While
this is still a low radiation dose, high-altitude cosmic radiation has a large neutron
radiation component which has a high impact owing to its biological effectiveness (10
to 100 times more effective than gamma rays). Hence, the radiation exposure offers
grounds for concern.
Radiation dosage levels vary with levels of solar activity, flight duration, route of
operation, latitude (increasing at higher magnetic latitudes) and altitude (increasing
with altitude up to a maximum of around 20km). Despite practical difficulties asso-
ciated with radiation dose measurements, owing to the high neutron content of the
radiation, a number of studies have made assessments of radiation doses at a variety
of latitudes and subsonic cruising altitudes, typically 9-13km, and suggest that air-
crews are exposed to doses between 2 and 10 micro-Sieverts per hour (
µ
Sv h
-1
)
(Reg-
ulla and David, 1993; Schalch and Scharmann, 1993; Beaujean et al, 1998; O'Brien
et al, 1998; Schrewe, 1999).
4
This equates to an annual average radiation dose in
the region of 3-6 milli-Siverts per year (mSv yr
-1
), assuming typical aircrew work
patterns (Blettner et al, 1998; Hammer et al, 2000). Measurements on aircraft oper-
ating at higher altitudes, such as Concorde, suggested a higher received dose from
9-13
µ
Sv h
-1
(Bagshaw, 1999).
