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TABLE V

NOREPINEPHRINE EXCRETION - HOUSTON CONTROLLERS

ug/100 mg

Creatinine S.D.
Day - First Half (D-1) 3.74 1.00 1
Day - Last Half (D-L) 3.92 0.99 1
Post Day - Night Sleep (P-D-N) 2.44 1.06 ]
Mid - First Half (M-1) 2.76 0.41 2
Mid - Last Half (M-L) 2.96 0.73 ?
Mid - Post Work (M-P) Day Sleep 2.66 0.72 ?

Significance

tk Level

D-1 vs D-L -0. 769% N.S.
D-1 vs M-1 4.44 -01 1
D-1 vs M-L 3.88 01 1
D-1 vs M-P 4.36 01 ]
D-1 vs P-D-N 8.09 01 ]
D-L vs M-1 5.58 01 }
D-L vs M-L 4,58 201 1
D-L vs M-P 5.45 .01 1
D-L vs P-D-N 6.78 01 ]
1

M-1 vs M-L -1.66 N.S,
M-1 vs M-P 0.63 N.S. ?
M-1 vs P-D-N ' 1.38 N.S. }
?

M-L vs M-P 2.12 N.S.
M-L vs P-D-N 2.79 +05 ?
2

M-P vs P-D-N . . 0.99 N.S.

*Correlated t test - listed are the t-values for the various comparisons.
¢ — (N=16)

»
*kNegative values mean that the second variable is higher than the first. rr

12



jen “doubled
ifts for the

| ace

turnoffs from the runways; the taxiways are
wide and straight; and the ramp areas are capa-
cious and arranged in an orderly way. The air-
port property, located about 18 miles north of
Houston, is extensive and being removed from
heavily populated areas aircraft noise is not a
disturbing factor for the citizens of the city.

* Noise complaints, so frequent at O’Hare, were

not a factor for controllers to deal with at
Houston.

Houston Approach Control handles approaches
and departures at several other airports in the
area including Ellington AFB and Hobby Air-
port. Intercontinental Airport is primarily an
air carrier terminal with little general aviation
traffic, in this respect similar to O'Hare. At the
time of this study Intercontinental had about 500
operations per day and the Tracon worked about
200 additional aircraft per day. At the time of
the O’Hare study, that airport had up to 2000
operations per day.

All these features at Houston Intercontinental
contribute to an airport that is apparently ideal
from the standpoint of air traffic control: spa-
ciousness, moderate traffic density, new and com-
fortable facilities, good, visibility, runways that
do not cross, flat terrain, and wide protected
areas. Most of these conditions are in exact con-
trast with those that obtained at O’Hare at the
time of that study. Houston Intercontinental
should, hypothetically, be situated lower down on
the air traffic controller stress spectrum than was
O'Hare if work load and physical working condi-
tions are the principal stressors. The old O'Hare
Tower, on the other hand, was antiquated with
respect to equipment and physical appointments
for the comfort and convenience pf controllers.
Facilities in the new tower at O’Hare are pre-
sumed to have rectified those problems.

TI. Results,

A. Heart Rate. Mid-shift/day-shift compari-
sons are presented in Table 1. Because only one
controller was in the cab and one in the Tracon
on the mid-shift, numbers of subjects were too
few#for statistical treatment of the data, except
for the approach coxtrol position in the Tracon.
There, the elevation of the heart rate on the day
shift is significant at the one percent level of
probability. In all cases heart rates on the day
shift are higher than those on the mid-shift.
When different work positions are compared on

the two shifts, there are only » few places where
the heart rate differences are statistically sig-
nificant. On the dey shift approach control (84
beats per minute (bpm)) is slightly, but sig-
nificantly, higher (p<0.05) than ground control
(80 bpm). Heart rates were generally lower
during cab work than during radar work; how-
ever, cab work gave rise to slightly higher heart
rates than did coordinator work in the Tracon. On
the mid-shift the only significant difference
(<0.05) is between local control in the cab (77
bpm) and approach control (75 bpm). While
this difference has statistical validity, the physio-
logical significance of a 2 bpm difference is
questionable.

Individual mean heart rates were invariably
lower on the mid-shift than on the day shift;
the decreases ranged from 8%to 29%,

When tower and day-off activities were com-
pared, a few points of statistically significant
difference emerged (Table II). Again, the phys-
iological significance of some of the smal] differ-
ences must be doubted.

1, Comparison with O'Hare. Heart rates of
O'Hare controllers were invariably higher than
those of Houston controllers (Table III). Sev-
eral points of statistically significant difference
are apparent, primarily on the day shift. For
comparison, radar and cab positions at each of
the two towers have been combined to show
that the two facilities do not differ significantly

on the mid-shift, but aoe the day shift
(evening shift at O'Hare). None of the wor!
positions gave rise to significantly different heart
rates on the mid-shift. On the day shift, how-
ever, the cab -positions did give rise to signifi-
cantly higher rates at O'Hare. Pre-work heart:
fites’on both shifts were significantly higher at
O’Hare than at Houston.

B. Urine Chemstry.

1. Epinephrine (E). Values for E excretion
are listed in Table IV. Work load-related adre-

lary hyperactivity is apparent on the
day shift, increasing five to six times over E ex-
cretion during night sleep. All values for E
excretion during day shift work significantly
exceed the values for mid-shift work.

With regard to mid-shift work, the last half
of the shift is characterized by E excretion sig-
nificantly exceeding that found during the first
half. Day sleep after the mid-shift gave rise to



<.001 O'Hare vs Houston

COMPARISON OF CATECHOLAMINE, SODIUM, AND POTASSIUM EXCRETION

OF O'HARE CONTROLLERS, HOUSTON CONTROLLERS, AND VARIOUS OTHER GROUPS

TABLE XII

Data Source Ex NE* Nake Kee
O'Hare (Mid-shift, Last naity® 2.05 6.30 11.1 3.8
Houston (Mid-shift, pase Half) 0.86 2.96 7.8 2.0
O'Hare (Night Sleep) 0.59 2.59 6.6 2.1
Houston (Night Sleep) 0.26 2.44 7.0 1.3
O'Hare (Day Sleep)8 1.12 4.68 10.8 4.0
Houston (Day Sleep) 0.66 2.66 8.4 2.0
O'Hare (Day Shift - First naiey® 1.30 3.87 13.0 4.8
Houston (Day Shift - First Half) 1.56 3.74 10.4 2.9
Helicopter Crew (10 hr.
transatlantic flight) 2.15 4.80 9.4 1.7
Untrained men (10 hr.
simulator test) 3 1.84 5.40 13.0 3.4
C-135 Crew (10 hrs. flight) 1.36 4.47 9.2 2.7
C-130 Crew (New Zealang flight)3 1,09 3.62 7.4 2.1
Scientists - Off Duty); 0.88 3.18 9.9 4.6
Controls (Night Siegp)? 0.56 2.93 6.0 2.0
Controls (Day Work) 0.74 2.85 8.7 5.2
Aircraft Mechanics (Day Work)? 0.74 3.43 11.3 4.0

*ug/100 mg. creatinine

*imEq/100 mg. creatinine .


TABLE IX

POTASSIUM EXCRETION - HOUSTON CONTROLLERS

mg /100 mg
Creatinine S.D.
Day - First Half (D-1) 2.85 0.80
Day - Last Half (D-L) 2.18 0.74
Post Day - Night Sieep (B-D-¥) 1.25 0.50
Mid - First Half (M-1) 1.83 0.72
Mid - Last Half (M-L) 1.97 0.79
Mid - Post Work (M-P) 1.95 0.69
Significance
| te Level
D-1 vs D-L 4.11 01
D-1 vs M-1 4.81 01
D-1 ve M-L 4.45 01
D-1 vs M-P 3.20 01
D-1 vs P-D-N 7.28 01
D-L vs M-1 1.97 N.S.
D-L vs M-L 1.34 N.S.
D-L vs M-P 0.97 N.S.
D-L vs P-D-N 3.71 -01
M-1 vs M-L -0.86%% N.S.
M-1 vs M-P 70.61 N.s.
M-1 vs P-D-N , 3.00 +01
M-L vs M-P 0.07 N.S.
M-L vs P-D-N 2.87 -05 i
M-P vs P-D-N . . 2.94 205

*Correlated t test - listed are the t-values for the various comparisons,
o (N16)

#HNegative” values mean that the second variable is higher than the first,



TABLE I

COMPARISONS OF MEAN HEART RATES ON MID-SHIFT AND DAY SHIFT

Tower Mid- Day Significance
Position Shift Shift Level

Radar Positions

Approach control 75 84 0,01

Departure control 80 88 *

Supervisor Tracon 77 82 * q
Coordinator 83 87 * 3

Cab Positions

Local control 77 78 *

Ground control 80 80 *

Data positions ’ 77 81 N.S.

Supervisor 72 85 *

*Insufficient midshift data for statistical’ comparison.



ACS excretion
he day shift and
are are not sig-

p, the difference |

vork periods is
shift value ex-

n that shift at
Hay sleep is not
facilities. The
P not differ sig-

s’ excretion of

hift work than
icantly elevated

He

i —

over Na excretion during day sleep. There was
no significant difference in Na content of the
night work samples, nor was there any significant
difference in Na content of night work samples
and night or day sleep samples.

6. Potassium (K). K excretion during the first
half of the day shift differs significantly from
XK excretion during night work (Table IX), K
excretion is significantly reduced during night
sleep below K excretion during all work periods.
K excretion duririg day sleep significantly ex-
ceeds K excretion during night sleep.

D. Blood Chemistry. Table X shows that total
plasma phospholipid concentration does not vary
significantly with any of the work or day-off
conditions. With regard to phosphatidyl glyc-
erol, however, the levels are significantly higher
on the day shift than on the mid-shift. Neither
work condition is associated with phosphatidyl
“glycerol concentrations significantly different
from levels on days off.

1, Comparison with O’Hare. Total plasma
phospholipid levels in O'Hare controllers were
significantly higher than the levels in Houston
controllers (Table XI). The Houston air traffic
controllers did not differ significantly from con-
trol values. Because of the elevated total phos-
pholipids in the O’Hare population, all individual
phospholipids are correspondingly elevated, and
significantly so, over the Houston group. How-
ever, when the individual phospholipid levels are
normalized as percent of total phospholipid, it
becomes apparent that lecithin and phosphatidyl

" glycerol comprise about the same percentages in

both populations. The two tower groups differ
significantly with regard to phosphatidyl] ethanol-
amine, cardiolipin, and phosphatidic acid,
IV. Discussion.

Qualitatively, the results at Houston are sim-
ilar to those obtained at O'Hare. Day work at
Houston is generally more stressful than mid-
shift work, as indicated by all measures except
total phospholipid, and it is presumed that the
heavier traffic load on the day shift is the factor
esponsible. At O’Hare there was evidence of
adrenocortical hyperactivity at the end of the
mid-shift, presumably caused by the heavy dawn
traffic. At Houston there is some evidence of a
similar hyperactivity in that E, NE and ACS
excretion all increase during the last half-of the

mid-shift; however, E was the only metabolite for
which the increase was statistically significant.
Day sleep after the mid-shift at Houston was
not as effective as night sleep as indicated by the
higher excretion of all adrenal products during
day sleep than during night sleep.
Quantitatively, it is evident upon comparisons
of catecholamines that the Houston group as a
whole is not greatly different from various control
groups and is operating at a lower level of stress
than other groups engaged in strenuous or haz-
ardous work (Table XII). Table VII shows
the comparison of O’Hare and Houston results
normalized as percent of the baseline. It is ap-
parent from this chart that the principal differ-
ence between the two facilities occurs on the
mid-shift where the greater work load at O’Hare
is reflected in elevated catecholamine excretion.

ACS excretion can only be compared by means
of normalized data since the same techniques
were not used for both towers. Table VII shows
that the principal difference with regard to ad-
renal cortical activity occurs on the last half of
the day shift. The two groups do not differ on
the mid-shift,

Comparison of 17-OH corticosteroid excretions
of O’Hare controllers with other groups on which
the same measurements were made reveal that,
when on duty, O’Hare controllers rank somewhat
below aircrews flying long missions; when asleep
in the daytime, they rank slightly above on-duty
aircraft mechanics. The Houston controllers rank
considerably below values given for 17-ketogenic
steroid excretion for the general population.
These observations on urine chemistry are inter-
preted to mean that both groups of air traffic
controllers are well adapted to their jobs but are
autonomically responsive to the work load, as
reflected in their excretion of catecholamines. In
that regard, it is apparent that the O’Hare group
was operating at a considerably higher level of
excitation than were other groups, including the
Houston controllers (Table XII).

The plasma phospholipid data generally sup-
port the catecholamine data in that the mid-shift
at Houston is indicated to be less stressful than
the heavy traffic day shift. At O'Hare no differ-
ence based on plasma phospholipids could be
detected. Comparatively, the O’Hare group sig-
nificantly exceeds various control and stressed
groups, including Houston controllers, with re-



an insignificantly greater E excretion than did
work on the first half of the mid-shift. However,
E excretion during the last half of the mid-shift
significantly exceeded E excretion during day
sleep. E excretion during day sleep significantly
exceeded E excretion during night sleep. The
excretion of E during day work, however, is more
than twice E excretion during day sleep, indi-
cating the effect of work load.

2, Norepinephrine (NE). The mid-shift is
characterized by relative sympathetic nervous sys-
tem quiescence, whereas the day shift causes
moderate sympathetic stimulation (Table V).
The day shift is characterized by NE excretion
roughly 1.5 times the excretion of NE on the
mid-shift. The last half of the day shift leads
to insignificantly higher NE excretion compared
to the first half of the day shift. NE excretion
on the first half of the mid-shift does not signifi-
cantly exceed the excretion during either day or
night sleep. NE excretion during the last half
of the mid-shift is significantly greater than NE
excretion during night sleep, but not significantly
greater than NE excretion during day sleep. Day
and night sleep cannot be distinguished by NE
excretion with statistical validity.

8. Adrenocortico-stercids (ACS). 1Z-ketogenic
steroid values are listed in Table VI. The pattern
of excretion is similar to that of the catechol-
amines in that the day shift values significantly
exceed the mid-shift values. ACS excretion dur-
ing day sleep is not significantly different from
ACS excretion during day work. ACS excretion
during day sleep significantly exceeds ACS excre-
tion during mid-shift work and night sleep. ACS
excretion actually falls to its lowest level during
mid-shift work and is at its highest level during
the first half of day shift work.

4, Comparison with O’Hare. Urine from
O'Hare controllers was analyzed for 17-hydro-
xycorticosteroids; urine from Houston con-
trollers was analyzed for 17-ketogenic’ cor-
ticosteroids. Both compounds are valid stress
indicators. However, an exact equivalance be-
tygeen them has not been reliably established for
all levels of excretion. For comparison, therefore,
on-shift values from both groups of controllers
were converted to percent of the baseline values.
Baseline, in both cases, was taken to be the mean
of steroid excretion during night sleep. These
baseline percentages were then treated as indi-

vidual statistics for each urine specimen at each
facility.

Table VII compares data from both facilities,
At both facilities ACS excretion during the first
half of the day shift (0800-1200 at Houston,
1600-2000 at O’Hare) significantly exceeded the
level of excretion during the last half. Likewise,
ACS excretion during the first half of the day
shift significantly exceeded ACS excretion during
the first half of the mid-shift. At both facilities
ACS excretion during the first half of the day
shift did not significantly exceed ACS excretion
during day sleep. Further, at both facilities,
ACS excretion during day sleep significantly ex-
ceeded ACS excretion during the mid-shift.

The two facilities differ in that ACS excretion
during work on the first half of the day shift and
last half of the mid-shift at O'Hare are not sig-
nificantly different; whereas, at Houston ACS
excretion during the first half of the day shift
significantly exceeds ACS excretion during the
last half of the mid-shift. The last half of the
mid-shift at O'Hare was characterized by a sig-
nificantly elevated ACS excretion over the last

half of the day shift. At Houston, the difference |

in ACS excretion during those work periods is
also significant; however,-the day shift value ex-
ceeds the mid-shift value. At O’Hare, ACS ex-
cretion during day sleep significantly exceeded
ACS excretion during the last half of the day
shift; at Houston, the difference was insignificant.
The difference between ACS excretion during day
sleep and during the last half of the mid-shift
was not significant at O'Hare; at Houston ACS
excretion during day sleep significantly exceeded
ACS excretion during the last half of the mid-
shift.

Table VII shows, in terms of percentages of
the baseline values, that ACS excretion during
the last half of the day shift at Houston signifi-
cantly exceeded ACS excretion on that shift at
O'Hare. ACS excretion during day sleep is not
significantly different at the two facilities. The
mid-shifts at the two facilities do not differ sig-
nificantly with regard to controllers’ excretion of
ACS.

5. Sodium (Na). Na excretion was signifi-
cantly greater during day shift work than during
mid-shift work (Table VIII). Na excretion was
significantly greater during day shift work than
during night sleep, but not significantly elevated

over I
no sig
night
differe
and n

6. I
half «
KK exc
excret
sleep
K ex
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ignificance


| a

gard to total phospholipids and exceeds control
(unstressed) groups, including Houston con-
trollers, on the basis of phosphatidyl glycerol.
The Houston controllers as a group do not differ
significantly from control groups (Figure 1).
When the two groups’ individual phospholipid
levels are normalized as percent of total phos-
pholipid, it is apparent that their amplitudes of
change in total phospholipid and phosphatidyl
glycerol as a function of work load are about the
same (Table XI). The Houston group exhibits
a significantly lower percentage of phosphatidyl
ethanolamine, cardiolipin, and phosphatidic acid.
The conclusion to be derived from these observa-
tions on the normalized data is that both groups
were adapted to about the same extent to the
long-term stress, except that the O’Hare group
was operating at a higher level of stress than was
the Houston group.

The mid-shift at Houston per se does not ap-
pear to be particularly stressful as judged by the
measures used in this study. O’Hare and Houston
controllers differ in this regard only with respect
to catecholamine excretion. Generally, O'Hare
controllers excreted a significantly greater amount

of catecholamine on the mid-shift than did
Houston controllers, a reflection, probably, of the
greater traffic load at O'Hare. While mid-shift
work itself must be considered light in terms of
numbers of aircraft at both facilities, it exacts a
penalty from the controllers in the form of in-
adequate off-duty rest. This conclusion is reached
to some extent from controllers’ verbalizations
but, more objectively, from their group biochem-
ical profile which shows that in both groups
catecholamine and steroid excretion during day
sleep were either greater than or not significantly
different from levels of those compounds in on-
duty speciments.

It can be generally concluded that the level of
stress at the Houston Intercontinental Airport
Tower is significantly lower than it is at the
O'Hare Airport Tower. The reasons appear to
be related to the lighter traffic and the superior
facilities at Houston. Such being the case, the
data support controllers’ practice of moving from
high-density, high-stress locations to lower-den-
sity facilities when either air safety or the em-
ployee’s health is jeoparized.

REFERENCES

1, Dawson, R. M. C., N. Hemington, and J. B. Daven-
port: Improvements in the Method of Determining
Individual Phospholipids in a Complex Mixture by
Successive Chemical Hydrolyses, BIOCHEM. J.
84497, 1962.

2, Few, J. D.: A Method for the Analysis of Urinary
17-Hydroxycorticosterolds. J. ENDOCRIN, pp. 31-46,
1961.

8 Ploriea, V. and R. Moses: Autopiated Differential
Fluorometric Analysis of Norepinephrine and Epi-
nephrine in Blood Plasma and Urine. BIOCHEM.
MED. 5:483-504, 1971.

4, Hale, H. B, C. A. Anderson, E. W. Williams, and
E, Tanne: Endocrine-Metabolic Effects of Unusally
Long or Frequent Flying Missions in C-130E or
C-185B Alreraft ... AEROSPACE MED, 39:561-570.
1968.

5. Hale, H. B, J. P, Hills, Jr, and E. W. Williams:

#Endocrine and Metabolic Changes During a 12-Hour
Simulated Flight ~ . APROSPACE MED. 36:717-719,
1965.

6 Hale, H. B.: FE. W. Williams, and C. J. Buckley:
Aeromedical Aspects of the First Non-Stop Trans-
atlantic Helicopter Flight: III. Endocrine Metabolic
Effects, AEROSPACE MED. 40:712-718, 1969.

7. Hale, H, B., 8. W. Williams, B. N. Smith, and C. E.
Melton: Excretion Patterns of Air Traffic Controllers,
AEROSPACE MED. 42 :127-138, 1971.

8. Melton, C. E., J. M. McKenzie, B. D, Polis, G. E.
Funkhouser, and P, F, Iampletro: Physiological Re-
sponses of Air Traffic Controllers: O'Hare Tower.
Office of Aviation Medicine Report No. FAA~AM-
71-2, 1972,

9, Peters, J. H.:*The Determination of Creatinine in
Blood and Urine with the Photoelectric Colorimeter.
J. BIOL, CHEM. 146 179-186, 1942,

10. Polis, B. D., B, Polis, J. deCani, H. P. Schwarz, and
L, Drelsback: Effect of Physical and Psychic Stress
on Phosphatidyl Glycerol and Related Phospholipids.
NADC-MR-6805, 1968.

11. Polis, B. D., E. Polis, J. deCani, H. P, Schwarz, and
L. Dreisback: Effect of Physical and Psychic Stress
on Phosphatidyl Glycerol and Related Phospholipids.
BIOCHEM MED. 2:286-312, 1969.

12, Polis, B, D., H. P. Schwarz, E. Polis, and L, Dreis-
back: Effects of Physical and Psychic Stress on
Phosphatidy] Glycerol and Related Phospholipids in
Humans and Animals, Proc. XVII Cong. Aviation
and Space Med., 1968.

18. Saldivar, J. T., Jr.: A Simplified Technique for Rapid
Application of Dry ECG Electrodes. AEROSPACE
MED. 4:456-457, 1970.



Doc 4

FAA

po ERA LIDRARY

24 eRe Pe a hl
/- | — PHYSIOLOGICAL RESPONSES IN AIR TRAFFIC
. _ CONTROL PERSONNEL: HOUSTON

~ INTERCONTINENTAL TOWER

C. E. Melton*

J. M. McKenzie*
B. David Polis**
Marlene Hoffmann*
J. T. Saldivar, Jr.*
*Civil Aeromedical Institute
Federal Aviation Administration
Oklahoma City, Oklahoma
**Aerospace Medical Research Department
U. S. Naval Air Development Center, Johnsville
Warminster, Pennsylvania

December 1973

Availability is unlimited. Document may be released
to the National Technical Information Service,
Springfield, Virginia 22151, for sale to the public.

Prepared for
DEPARTMENT OF TRANSPORTATION

t - FEDERAL AVIATION ADMINISTRATION
| SF Office of Aviation Medicine

Washington, D.C. 20591



TABLE IIL

COMPARISONS BETWEEN HOUSTON AND O'HARE HEART RATES

AVERAGE HEART RATE

Activity Houston O'Hare Significance Level*
Mid-Shift (0200 to 0600) 72 77 N.S.
Day Shift

(1000 to 1400 Houston)

vs (1700 to 2100 O'Hare) 83 90 -05
Mid-Shift

CAB Position 78 81 N.S.

Radar Position 75 78 N.S.

Supervisor Position 76 76 N.S.

#kPre-work 80 86 05
Day Shift

CAB Position 81 95 .002

Radar Position 84 87 N.S.

Supervisor Position 86 90 N.S.

*kPre-work , 84 95 01

*Mann-Whitney U Test
*#kOne-minute heart-rate determination at the time of instrumentation.

10

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TOTAL PHOSPHOLIPID AND PHOSPHATIDYL GLYCEROL
AS STRESS INDICES IN HUMAN POPULATION

TOTAL PHOSPHOLIPID P

CONTROLS

SIMULATED
COMBAT FLIGHTS

SCHIZOPHRENICS —&

| COMBAT FLIGHTS
SCHIZOPHRENICS
EXTENDED

COMBAT FLIGHTS

O'HARE
CONTROLLERS

HOUSTON '

CONTROLLERS '
1 1 pty 1 1 1 J

9° 20 40 60 80

. BMP/L

--~Demarcation of significant differences
at the 1% level

EXTENDED
COMBAT FLIGHTS
Ctontro.iers WALL
HOUSTON ‘
CONTROLLERS ! uy ;
ce] 1000 2000 3000 4000
BMP/L
PHOSPHATIDYL SLYCEROL
CONTROLS i
SIMULATED \
H

Fioune 1, Comparison of plasma phospholipid levels in various human groups.

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bottle containing 2 cc of 12N HCl. This aliquot
was frozen and later analyzed for epinephrine
and norepinephrine. The remainder of the urine
was placed in a 500 ml plastic bottle and frozen
at the work site. When a sufficient number of
specimens had accumulated, they were shipped
by air to the Civil Aeromedical Institute in
Oklahoma City and stored in deep freeze until
thawed for analysis.

The sample containing only boric acid was used
for the analysis of 17-ketogenic steroids; the
aliquot which had been further acidified (to
0.04N) with HCl for analyses of catecholamines,
creatinine, Na+ K+. To minimize errors in
precise timing of the urine collection and partial
loss of sample, data were reported in weight
units (e.g, nanograms, etc.) per 100 mg of creati-
nine. Creatinine was measured by an automated
modification of the Jaffe method.® A two-channel
atomic absorption instrument (Instrumentation
Laboratories, Model 353) was used to measure
Na+ and K+; the instrument was calibrated
against standards and blank diluent. Catechol-
amines were measured by adsorption onto 500 mg
of alumina, elution with acetic acid, and fluoro-
metric analysis by a method essentially that of
Fiorica and Moses.’ Catecholamine standards
used to calibrate the method were dissolved in a
medium saturated with boric acid containing
0.04N HCl because of the tendency of the cate-
cholamines to form strong borate complexes.

An automated modification of the Norymberski
technique? was developed for the analysis of 17-
ketogenic steroids; details of the technique will
be reported later. Essentially, it involves prior
reduction of interfering 17-ketosteroids and sub-
sequont oxidation of ketogenic compounds, fol-
lowed by extraction and purification of the
extract; the extract is dried in vacuo, dissolved
in methanol and analyzed by an automated device
which employs an on-line extraction to remove
interfering chromogens. Data are corrected for
loss of sample by measuring the recovery of
added C-cortisol, and for incomplete oxidation
by comparison with companion data from control
tubes containing cortisol in amounts representing
an average frine concentration.

A 15 ml blood specimen was drawn into a
heparinized plastic syringe from the antecubital
vein of each subject at the end of each work
week that they were under observation ’and a
third specimen was taken when each subject re-

turned to work after two days off. The blood
specimens were immediately centrifuged and the
blood plasma was removed and frozen. Thus,
three blood specimens were taken from each sub-
ject. The accumulated frozen plasma specimens
were taken by courier to the Naval Air Develop-
ment Center (Johnsville), Warminster, Pennsyl-
vania where the plasma specimens were analyzed
for phospholipids by the method of Dawson? as
used by Polis, et al.1°1#

C. Description of the Site and Conditions of
Work. The Houston Intercontinental Tower is a

new structure of the golf-tee type with the Term-
inal Radar Approach Control (Tracon) room

located on the ground floor. An elevator is used °

to go from the Tracon room to the cab. Con-
trollers normally change positions approximately
every two hours, working about half of the time
in the cab and half in the Tracon.

At the time of this study the tower was op-
erating on a “straight five-day” shift rotation
pattern: each controller worked five evening
shifts, five day shifts, evenings again, five days
again, and finally five mid-shifts, with each five-
day work week followed by two days off. Thus
each controller would have been scheduled to
work “mids” every fifth week but the traffic on
the shift was so light one man could usually
handle it. The rest of the team then “doubled
back” on to the day or evening shifts for the
fifth week of the sequence so that, in practice,
each man worked a week of mids every 6-10
weeks. For this study, however, two controllers
manned the tower during the mid-shift, one in
the cab and one in the Tracon room.

The tower has since abandoned the straight
five-day shift rotation pattern in favor of the
2-2-1 rotation (a five-day work week consisting
of two evenings, two days, and one mid). On
the 2-2-1 rotation, the controllers work a different
shift every day. A comparison of the controllers’
physiological responses to these two shift rotation
patterns will be the subject of a subsequent report.

Houston Intercontinental Airport is a relatively
new facility with two long runways, one east-
west and one southeast-northwest, with their
westerly ends approximately each other so that
the runways form a blunt V open to the south-
east. One runway is ordinarily used for takeoffs
and the other for landings, thus expediting the
flow of traffic. There are numerous high-speed


ps/100 mg

Creatinine S.D.

Day - First Half (D-1) 1541.04 481.04
Day - Last Half (D-L) 1348.00 464.55
Post Day - Night Sleep (P-D-N) 832.92 261.90
Mid - First Half (M-1) 735.96 205.68
Mid - Last Half (M-L) 1018.09 309.95
Mid - Post Work (M-P) 1299,70 381.71

, Significance

te Level

D-l vs D-L 2.91 .05
Del va M-1 ; 7,29 01
D-1 ve M-L 4.22 -01
Del vs M-P 1.60 N.S.
D-1 vs P-D-N 6.76 -01
D-L va M-1 5.49 01
D-L ve M-L 2.69 .05
D-L vs M-P 0.38 N.S.
D-L vs P-D-N 4.58 -O1
MOL vs M-L *-5.51 01
M-1 vs M-P , -5.23 -O1
M-1 vs P-D-N -1.24 N.S.
M-L vs M-P -2.43 +05
M-L vs P-D-N . 1.85 N.S.
M-P vs P-D-N 4.11 -O1

TABLE VI

17-KETOGENIC STEROID EXCRETION - HOUSTON CONTROLLERS

*Correlated t test - listed are the t-values for the various comparisons.

(N=16)

»

weNegative values mean that the second variable is higher than the first.



TABLE VIII

SODIUM EXCRETION - HOUSTON CONTROLLERS

(N=16)

witvegative Salues mean that the second variable is higher than the first.

mEq/100 mg
Creatinine S.D.
Day - First Half (D-1) 10.43 2.94
Day - Last Half (D-L) 9.46 1.92
Post Day - Night Sleep (P-D-N) 6.99 2.02
Mid - First Half (M-1) 7.48 2.17
Mid - Last Half (M-L) 7.76 2.23
Mid - Post Work (M-P) 8.41 2.74
Significance
tk Level
D-1 vs D-L . 1.45 N.S.
D-1 vs M-1 3.25 -01
D-1 vs M-L 2.67 05
D-1 vs M-P 1.94 N.S.
D-1 vs P-D-N 4.65 01
D-L vs M-1 3.40 .O1
D-L vs M-L 2.72 +05
D-L vs M-P 1.24 N.S.
a list D-L vs P-D-N 3.50 01
M-1 vs M-L -0. 57% N.S.
bn val M-1 vs M-P 71.09 N.S.
values. M-1 vs P-D-N , 0.68 N.S.
M-L vs M-P -0.93 N.S.
M-L vs P-D-N 0.89 N.S.
M-P vs P-D-N . . 1.73 N.S

*Correlated t test - listed are the t-values for the various comparisons.


PHYSIOLOGICAL RESPONSES IN AIR TRAFFIC CONTROL PERSONNEL:
‘HOUSTON INTERCONTINENTAL TOWER

L Introduetion.

Physiological and biochemical measurements
made on 22 air traffic controllers at the old (1968)
O'Hare Airport Tower in Chicago indicated that
the heavy traffic evening shift was principally
characterized by a sympatho: -adrenomedullary re-
sponge, and that light traffic midnight-to-
8:00 a.m. shift (mid-shift) was further character-
ized by adrenocortical hyperactivity. Further, it
was shown that recovery during the off-duty
period (day sleep) was incomplete during a week
of mid-shifta. Plasma phospholipid determins-
tions as well as urine chemistry indicated that

O'Hare controllers were under considerable stress.

e various indicators showed that the stress was
comparable to that experienced by combat per-
sonnel, populations ,of schizophrenics, air crews
on extended flights, and altitude chamber tech-

jicians experiencing six hours of decompression.**

It is necessary to express stress in comparative
terms because standard units of stress have not
been established. The findings of the present
study at Houston Intercontinental Tower, a me-
dium-density facility, are intended to be com-
pared with those at O’Hare Tower and thus
ultimately establish a spectrum of stress for air
traffic controllers engaged in different types and
intensities of work. Such data would be useful
in personnel placement and career progression
planning.

The approach in this experiment, as with the
study at O'Hare, was to compare the physiological
responses of Houston controllers on the heavy
traffic day shift (0800-1600) with their responses
on the light traffic mid-shift (0000-0800).

#
IL. Methods.

Sixteen controllers (5 crew chiefs, 9 journey-
men, 2 trainees) volunteered for the study. Each
subject was observed during five consecutive day
shifts (0800-1600) and five consecutive mid-shifts
(0000-0800).

A. Physiological Measurements, Instruments-
tion consisted of dry ECG electrodes" from which
led 86 ga. insulated copper wires connected by
means of a 3-wire cable to an Avionics Model 350
Electrocardiocorder. The ECG was recorded on
tape continuously throughout the work periods.
The taped ECG’s were reduced to one-minute
heart rates on a tape reproducer that was con-
nected to an electronic counter. The counter ac-
cumulated one minute of recorded. ECG and then
dumped the count through a printer onto paper
tape. Activity logs were kept by observers for
correlation with the heart rates. The logs were
also used to exclude periods of physical activity
such as walking up and down stairs, meal breaks,
etc., that might affect the heart rate in a way un-
realted to the ATC task.

At the time of instrumentation, pre-shift heart
ratewas noted for a one-minute period in connec-
tion with an operational check of the recording
system. This rate cannot truly be considered as a
resting heart rate because of preceding physical
activity incident to reporting for work (walking
from the parking lot, going to the locker room,
“horseplay,” anxiety about biomedical procedures,
etc.).

B. Biochemical Measurements. Urine was col-
lected from each subject throughout the two work
weeks that each subject was under observation.
The two on-duty collection periods were the first
four and the last four hours of each shift. An
overnight specimen was collected following each
day’s work. As each collection period began with
the bladder empty, the urine collected was fairly
representative of that period. At the end of the
first four hours of work the subjects were asked
to void, thus terminating that collection period.
The second collection period was terminated at
the end of the work day.

Urine was cullected into screw-cap plastic bags
containing 50 gm of dry boric acid. At the end
of a collection period the urine volume was meas-
ured and a 50 ml aliquot was placed in a plastic



TECHNICAL REPORT STANDARD TITLE PAGE

1. Report No. 2. Government Accession No. 3. Recipient's Catalog No.

| FAA-AM-73- 21

| [A Titte and Subtinte
| PHYSIOLOGICAL RESPONSES IN AIR TRAFFIC CONTROL
PERSONNEL: HOUSTON INTERCONTINENTAL TOWER

5. Report Date
December 1973

6. Performing Orgonization Code

5 7.” Author(s)
| Cc. E, Melton, J. M. McKenzie, B. David Polis,
Marlene Hoffmann and J. T, Saldivar, Jr.

8. Performing Organization Report No.

9. Performing Organizotion Name ond Address 10. Work Unit No.
| | FAA Civil Aeromedical Institute

P. 0. Box 25082

TI. Contract or Grant No.

Oklahoma City, Oklahoma 73125

13. Type of Report and Period Covered

12, Sponsoring Agency Name and Address
Office of Aviation Medicine

Federal Aviation Administration
800 Independence Avenue, S.W. 14.

|. Sponsoring Agency Code

Washington, D.C, 20591

15. Supplementary Notes

Work was performed under Task No. AM-B-72-PHY-55.

16. Abstract

Biochemical and physiological indices of stress showed that the level of stress of
16 air traffic controllers at the Houston Intercontinental Airport Tower was
indistinguishable’ from that of control populations. While the level of stress
was lower than that among O'Hare Tower controllers, both groups showed about the
same degree of adaptation. Day work (heavy traffic load) at Houston was
characterized by elevated levels of all stress indicators as compared with the
mid-shift (light traffic); epinephrine excretion increased significantly during
the last half of the mid-shift as compared with the first half, Urinary stress
i indicators (17-ketogenic steroids, epinephrine, norepinephrine) were all

! significantly elevated during day sleep as compared with night sleep, indicating
less effective rest during day sleep. The data support the practice of

! controllers moving from high-stress, high-density locations to lower-density

{ facilities when either air safety or the controller's well-being is in question.

,

17. Key Words 18. Distribution Stetement
# Availability is unlimited. Document may be
Stress; Air Traffic Controllers released to the National Technical Informa-

tion Service, Springfield, Virginia 22151,
for sale to the public,

19. Security Classif. (of this report) ‘2. Security Clossif. (of this poge) 21. No, of Pages | 22. Price

ce

Unclassified Unclassified 19 $3.00

Form DOT F 1700.7 (#-69)


TABLE IV
EPINEPHRINE EXCRETION - HOUSTON CONTROLLERS
ug/100 mg
Creatinine S.D.
Day - First Half (D-1) 1.56 0.95
Day - Last Half (D-L) 1.36 0.68
Night Sleep (P-D-N) 0.26 0.11
Mid-Shift - First Half (M-1) 0.61 0.31
Mid-Shift - Last Half (M-L) 0.86 0.53
t Mid-Shift - Post Work (M-P) Day Sleep 0.66 0.55
Significance
tke Level
D-1 vs D-L 2.09 N.S.
Del vs M-1 4.14 01
D-1l vs M-L 4.06 01
D-1 vs M-P 5.20 -O1
D-1 vs P-D-N 6.05 .O1
D-L vs M-1 5.68 01
D-L vs M-L 4.11 01
D-L vs M-P 5.04 01
D-L vs P-D-N 7.35 01
w-1 ve M-L -3.28 01
M-1 ve M-P 70.54 N.S.
M-1 vs P-D-N » 5.36 01
M-L vs M-P 2.76 +05
M-L vs P-D-N 5.15 01
M-P vs P-D-N . . 3.43 01

*Correlated t test - listed are the t-values for the various comparisons,
’ (N=16)

v
*eiNegative values mean that the second variable is higher than the first.


D
TABLE VIT t
URINARY EXCRETION PRODUCTS EXPRESSED E
AS PERCENT OF BASELINE VALUES ¥
O'HARE VS HOUSTON* ‘
Epi Norepi Corticosteroid
D-1 -1,04 N.S.# 0.31 N.S. 1.39 N.S.
D-L 1.85 Ns. 2.43 < .05 2.40 < .05 }
Mel 4.20 < .01 1.84 N.S. -0.16 N.S. ot
M-L 4.56 < .01 5.15 < .01 -1.30 N.S. , t
M-P 2.42 < .05 3.53 ¢ .O1 1.05 N.S. _
I
*t test of a difference between two sample means. ‘The chart is a list t
of t-values, followed by level of significance. ¥
**Negative numbers mean that O'Hare values are tower than Houston values. H ‘
*
See Tables IV, V, and VI for key to symbols in column 1. Poy
¥
. ¥

14