Dose Assessment for Inhabitants Evacuated from the 30-km Zone Soon after the
Chernobyl Accident
Tetsuji IMANAKA and Hiroaki KOIDE
Research Reactor Institute, Kyoto University
Kumatori-cho, Sennan-gun, Osaka 590-04, Japan
Apparently, findings by Yaroshinskaya andLupandin are in contradiction to the opinion of theauthorities. It seems to be difficult to reconcile the twodifferent opinions about the occurrence of ARS
among inhabitants around Chernobyl. So, we can only
say, which is true? In order to answer this question,
we come up to another question. How much was thelevel of irradiation for inhabitants? Could it be thelevel that causes ARS?
In this report we try to evaluate irradiation dose of
inhabitants around Chernobyl until their evacuation,
based on the data which became available recently.

Introduction
The first detailed report about the consequences of
the Chernobyl accident was presented to IAEA fromthe USSR government in August 1986, about 4
months later since the beginning of the accident [1].
According to this report, more than two hundred casesof acute radiation syndrome (ARS) occurred as aresult of the accident, among which 29 persons died(besides, two persons died on the day of the accident
by other reasons). All cases of ARS were stated tohave happened to firemen and workers involved
immediately in the accident, while there was no caseof ARS among inhabitants around the Chernobyl site.
This opinion of the former USSR authorities was
succeeded till now in reports of internationalorganization such as IAEA, WHO, OECD/NEA [2-4].
Along with the process of the collapse of the
USSR, there appeared several publications thatindicate a number of cases of ARS among inhabitantaround the Chernobyl site. Our attention should be
paid to the following two reports. The first one is thesecret protocols of the Operative Group of the Politic
Bureau of the Central Committee of the Communist
Party of the Soviet Union, disclosed in 1992 by Alla
Yaroshinskaya [5, 6]. Many pieces of information canbe found in this document about ARS among
inhabitants, including those for children. She
contributed herewith an article, ″Impact of Radiationon the Population during First Weeks and Months
after the Chernobyl Accident and Health State of the
Population 10 Years Later.″ One sentence is citedhere from the protocol on May 10, 1986: ″The total
number of persons in hospitals is 8,695, including 238
persons with diagnosis of radiation syndrome, 26 ofwhich are children.″ Another important report about
ARS was made by Vladimir Lupandin [7]. He
investigated in 1992 medical records made in
May-June 1986 at the Central District Hospital of the
Khoiniki district of the Gomel region of Belarus,
located adjacent to the Chernobyl site. Although atheft of the medical archive happened in November
1990, he found 82 medical records of inhabitants who
suffered from irradiation. Among them he confirmed
8 cases of ARS. Details of his finding are described in
his article ″Chernobyl 1996: New Materials
concerning Acute Radiation Syndrome around
Chernobyl”

Materials and methods
Under the tradition of the Soviet system, theinformation concerning the consequences of theChernobyl accident had been treated to be secret. As
also disclosed by Yaroshinskaya [5], for example, theSoviet government issued on June 27, 1986 an order,″To consider as secret: data about the accident; data
about results of treatment of sufferers; data on
irradiation of personnel involved in liquidation of theconsequences of the disaster.″ Although some data on
the radiation situation were included in the USSR
report in 1986, they were not enough to do
independent analysis or to check the validity of
estimates contained in it. Through the Soviet period,
we could only find fragmentary information about theradiation situation soon after the accident around theChernobyl site.
In 1996, interesting data were presented in reportsof the collaboration work between European
Commission and three affected CIS countries(Ukraine, Belarus and the Russian Federation) [8].
Dose rate on May 1, 1986
Fig. 1 shows the radiation situation at settlements
within the 30-km zone around the Chernobyl site on
May 1, 1986, five days after the accident [9]. It is
stated that these data were measured by special teamsof the Chernobyl NPP staffs and other specialist,
using GM counter at 1 m above the ground.
As seen in Fig. 1, a large variation is observed in
the spatial distribution of radiation situation. The
maximum of 3,306 µGy/h is observed at village
Krasnoe about 6 km north from the site. High valuesof dose rate are generally observed at settlements inthe north half of the 30-km zone, which corresponded

121

131

North-south distance from the Chernobyl NPP (km)

30

261
104
PogonnoeDernovichi
252
348
OrevichiRadin
696
Molochki
348

20

Kranosel 870
Borshchevka
122
Doblyadi

10 96Denisovich 174

0157
Puchin104

157
Vigrebnaya

Savichi

435
Ulasi

3045
Usov

70
Suvidi70

1044
Kulazhin
1914
Kryuki

ZaleseZimovishche
1053

ChNPP

Pirki
96

957
Mashevo
3306
Krasnoe

131 Khutor Les
252
KhatkiBenyovka
244
Rudki
261
139
Nov. Shepelichi
148
165
Yanov
Krasnoe3045
174 Nov. Krasnitsa
1740

70
Grushnoe 44

139 148
Chikalovichi
Chapaenka

870
Krivaya Gora

9
Chistogolovka 1044 331
Starocele
653
Kopachi174
87 St. Krasnitsa
435
87
Lelev Koshovka
Lubyanka
35
Stechaika
Ilintsi
26
78
61
87
174
Razezhnee
Parishev
Chernobyl
Korogod
122
35 Bichiki
96 Zalese
Lodizhichi
35
87
GlinkaCherevach78
122 Chipol
Rodinka
87
174

-10

-20

44

Rudnya Veresnya

Rossokha

-30
-30

-20
-10
0
10
20
East-west distance from the Chernobyl NPP (km)30

Fig 1. Dose rate in air at settlements within the 30-km zone around the Chernobyl site on May 1,
1986 [9], unit: µGy/h.
Belarus, maybe, with GM counter.
to the fact that radioactive clouds from the destroyed
In the solid line of our calculation (calculation 1),
reactor moved to north-west and north from thethe deposition of other nuclides (18 nuclides) thandestroyed in the first and second days after the137
accident [1, 10].
Cs were determined from their deposition ratios to137
It was reported that the first evacuation of 45,000
Cs reported by Izrael et.al. [13], values of which are
inhabitants in Pripyat, a city built next to theshown in Table 1 together with dose rate conversion
Chernobyl site for workers of the station, was carriedfactors per unit density of each nuclide on the ground.
out on April 27, 1986, the next day of the accident [1].
Calculation of exposure rate in air per unit deposition
The second evacuation of inhabitants who were livingof 137Cs was made by the next equation.
within the 30-km zone was made during the periodr(t ) =DFi ⋅ DRi ( t )(1)from May 3 to May 5 [11]. So, these people stayed inithe highly contaminated area for 7-9 days. The
where r(t): γ-ray exposure rate at time t calculated at 1
number of inhabitants evacuated in the stage wasm above the ground from the mixture of depositedreported to be 90,000 [1]. The evacuation was finallynuclides, densities of which are normalized to unit
completed on May 14 [11].
137
Cs deposition, (µR/h)/(Ci/km2 of 137Cs)
DFi: exposure rate conversion factor from unit density
Dose rate change during the first days in the
Khoiniki districtof nuclide i on the ground, calculated by us based
An interesting data on dynamics of dose rateon the infinite plain model, (µR/h)/(Ci/km2)
change measured in the Khoiniki district, whichDRi(t): density ratio of nuclide i to 137Cs at time t.
corresponds to the north-west part of Fig. 1, is also
If we can reconstruct dynamics of exposure ratepresented in the same EC/CIS report [12]. In Fig. 2 ischanges during the first days after the accident,
shown the measured change of dose rate normalized
external irradiation at each settlement can be
per unit deposition of 137Cs in the Khoiniki district
calculated by combining the dose rate data in Fig 1
together with calculated ones by us. The measurementwith their changes.
of dose rate was carried out by Civil Defence ofAs seen in Fig. 2, the solid line (calculation 1)∑

122

(µR/h)/(Ci/km2)

Dose rate per unit Cs137 deposition

gives a little higher exposure rate
than the measured one for the firsttwo weeks after the accident. This
Measurement
Calculation I
period is critical in dose formation of
Calculation 2
inhabitants who were evacuated fromMay 3 to May 5. So, in order to fit
1000
the calculated curve to the measured,
we reduced the deposition ratios for95
Zr and 140Ba to halves of them inTable 2. Thus, we calculated thedotted line (calculation 2), showing agood agreement with measurements
for the first two weeks.
100
In the curve of the measured data,
0
10
20
30
40
an increase of exposure rate is noted
Time after the accident (days)
from May 16 to May. 20. It can beconsidered to reflect the late phase Fig. 2 Dose rate change in the Khoiniki district normalized per
release from the destroyed reactor that isunit deposition of 137Cs [12].
recently reported by Dobrynin et.al. [14],which may support our reduction of deposition ratios
Table 1 Composition ratio and dose rate conversion
for 95Zr and 140Ba.
factor of nuclides deposited around the Chernobyl
Procedures for dose estimation
Dose values of external irradiation from deposited site (Cs137=1) [13].
radionuclides on the ground, external irradiation fromradioactive clouds in air, and internal dose throughthe inhalation path are evaluated for inhabitants whostayed in their settlements until evacuation, based on
the following procedures.
Step 1: Calculation of external dose equivalent from
deposited nuclides on the groundThe next two assumptions were made in order tocalculate external irradiation.
A. All deposition occurred at a time at 12:00 on
April 27, about 36 hr after the accident
B. Dose rate change at each settlement can be
expressed with the curve of the dotted line in Fig.
2. In other word, the composition of deposited
nuclides was same for all settlements.
At first, the deposited density of 137Cs, ACs137[Ci/km2] is calculated by the next equation,
A Cs137 =R m ( M ay 1)
0.0087 ⋅ r ( M ay 1)(2)

NuclideHalf life

Sr91
Zr95
Zr97
Nb95
Mo99
Ru103
Ru106
I131
I133
I135
Te132
Cs134
Cs136
Cs137
Ba140
La140
Ce141
Ce143
Ce144

9.7 h
65.5 d17 h
35 d2.75 d39 d
367 d
8.04 d21 h
6.7 h
3.25 d2.05 y13 d30 y12.8 d
1.67 d32.3 d1.38 d284 dRelative
Dose ratecomposition
conversion(at the time offactorthe accident) (µR/h)/(Ci/km2)
1.2*
20
3.3
29
1.6*
29
3.3*
15
7.5
2.8
5.3
9.6
1.3
3.7
20
7.6
40*
12
35*
34
33
46
0.5*
29
0.3*
39
1
11
3.6
43
3.6*
39
3.5*
1.8
3.1*
4.9
2
0.55

where Rm(May 1) : absorbed dose rate in air on May * These values are evaluated by the author, considering inventory
ratios.
1, shown in Fig.1, µGy/h,r(May 1): exposure rate calculated by (1) at 12:00
12:00 day of evac
Dexp = ACs137 r(t)dt
on May 1 per unit deposition of 137Cs,(3)
12:00 Apr 27(µR/h)/(Ci/km2),
The day of evacuation was obtained or assumed from0.0087: conversion factor from µR to µGy.
the information in the paper by Likhtarev et.al. [11].
By the way, density on the ground of i nuclide,
Finally accumulated exposure dose in air is
Ai,(t) other than 137Cs can be easily obtained fromconverted into the value of external dose equivalent,values of deposition ratios given in Table 1.
Dground [Sv], using the following relation.
Then accumulated exposure dose in air until the
Dground = 0.61⋅0.82⋅0.0087⋅Dexp (4)time of evacuation, Dexp [R] is calculated by the next
where 0.0087: conversion factor of R to Gy
equation,
0.82: conversion factor of Gy to Sv
0.61: apparent shielding factor of∫123

for 1 week after incorporation, Sv/Ci,
0.00022: breathing rate, m3/sec,
0.61: apparent shielding factor.
Values of FIi are specially calculated by us toobtain internal dose for the short period (1 week) afterincorporation, using the next equation.

inhabitants.
Values of theses three parameters were chosen
also from the data by Likhtarev et.al.[11]. The
apparent shielding factor of 0.61 can be applied torural people who spent outdoors for 0.42 faction of
day and stayed in wooden houses (shielding factor =0.33) for the rest of time.

FI i = FIicrpi

Step 2: Estimation of external dose equivalent fromradioactive clouds
Usually, in assessments of the consequences ofhypothetical nuclear accidents, the amount of grounddeposition is evaluated from air concentration ofradionuclides. Here, inversely, integral concentrations
in air of nuclide i, Ci, [Ci/m3⋅sec] is evaluated,assuming deposition velocity of deposited nuclides,

Ci

Ai
Vi

The contribution of external irradiation fromradioactive rare gases and internal dose from the pathof ingestion are neglected in our procedures.
Results and discussion
The main purpose of this report is to investigate
the radiation situation around the Chernobyl site fromthe viewpoint whether or not there was a possibility ofirradiation that caused acute radiation syndrome
among inhabitants until their evacuation. On the other
hand, it is difficult to say univocally the level ofirradiation dose that causes acute radiation syndrome
because definition of acute radiation syndrome itself
is of unclear nature and it depends on many factors
such as irradiation conditions and individual factors.
According to ICRP [18], acute irradiation of 0.5 Sv isevaluated to be a threshold of slight bone marrow
injury. Following the traditional conception about
ARS, however, we consider here 1 Sv of dose
equivalent as the criterion of ARS.

where Ci: integral concentration in air of nuclide i,
Ci/m3⋅sec,
Vi: deposition velocity of nuclide i, m/s.
0.005 m/sec for iodine
0.002 m/sec for other nuclides
Values of Vi are obtained from the Reactor Safety
Study [15, 16].
External dose equivalent from radioactive clouds,
Dcloud [Sv] is obtained from the next equation∑ FC ⋅ C
i

(6)

i

i

where, FCi: dose conversion factor of nuclide i
calculated based on submersion model [16],Sv/(Ci/m3⋅sec),
0.61: apparent shielding factor chosen as the sameas Step 1.

Average irradiation dose
We have applied the above procedures of dose
assessment to five settlements; villages Usov, Krasnoe,
Kryuki, Borshchevka and Chernobyl city. Krasnoe is
the highest point in Fig. 1. About Usov (10km to NW)
and Chernobyl (15km to SE), external irradiation is
also evaluated by Likhtarev et.al. [11]. The report of
Lupandin includes typical cases of acute radiation
syndrome in Borshchevka (18km to NW). Kryuki(17km to NE) is located in the area of most highest
level of 137Cs contamination [19].

Step 3: Estimation of internal dose equivalent frominhalation of contaminated air
Based on the integral concentration obtained in
Step 2, internal dose equivalent from inhalation, Dinh
[Sv] can be calculated from the next relation,∑ FI ⋅ C

Dinh = 0.61 ⋅ 0.00022

i

i

(8)

where FIicrpi: dose commitment conversion factor
from inhalation of nuclide i evaluated by ICRP [17]FIrssi(7day) and FIrssi(50 year): internal dose
equivalent conversion factor of nuclide i, for 7 days
and 50 years, respectively, given by the RSS [16].

(5)

Dcloud = 0.61

FIrssi ( 7day)
FIrssi (50year )(7)iwhere, Ci: integral concentration of nuclide i,
FIi: inhalation dose conversion factor of nuclide i

Table 2 Estimates of average dose for inhabitants at settlements in the 30-km zone until
evacuation
Dose rate
Deposition
Day ofon May 1of 137Cs
evacuation(mGy/h)(Ci/km2)
Usov
3.045
May 3
430
Krasnoe
3.306
May 3
470
Kryuki
1.914
May 5
270
Borshchevka
0.870
May 5
120
Chernobyl
0.174
May 5
25
* Contribution from cloud is not included．
Settlement

Accumulated
exposure inair (R)*
64
69
40
18
3.6

124

External dose (Sv）Ground

Cloud

0.28
0.30
0.17
0.08
0.02

0.04
0.04
0.02
0.01
0.002

Inhalation
dose
（Sv）
0.13
0.14
0.08
0.04
0.01

Total
dose
（Sv）
0.44
0.48
0.28
0.13
0.02

Frequency (persons/ƒ ¢Log(D))

Results of our calculation aresummarized in Table 2. As seen in Table
2, the highest dose of 0.48 Sv was
obtained for inhabitants at village Krasnoe.
About 60 % of the total dose were
external irradiation from deposited
nuclides on the ground. About 30 and
10 % were from external irradiation fromclouds and inhalation path, respectively.
According to the results of Table 2, theaverage dose of inhabitants in settlements
within the 30-km zone around theChernobyl site did not reach 1 Sv of thecriterion for ARS,

500
Evaluated distribution
Log-normal fitting

400
300
200
100
0

1

100 Log(D (mSv))

10

Fig. 3 Distribution of evaluated individual external
dose of evacuees from Paryshev [9]Distribution of irradiation dose for inhabitants
It should be noted that values in Table 2 aregiven as estimates for average doses of inhabitants ineach settlement. Actual doses to individuals were
naturally distributed around average doses. In order toinvestigate the possibility of ARS, therefore, thedistribution of individual dose among inhabitants
should be taken into consideration. Many factors are
considered to be related with possible distribution ofirradiation doses; inhomogeneity of contamination,
variation of individual behavior, difference ofshielding ability of buildings, etc.
In the course of the EC/CIS work, individual
external doses were evaluated for 335 inhabitants who
evacuated from village Paryshev [20], located about
20 km south-east from the Chernobyl site (26 µGy/h
on May 1, 1986, see Fig.1). Questionnaires on daily
behavior and living conditions of individuals until
their evacuation were used to estimate individual
external dose. The result of their dose distribution isredrawn in Fig. 3 together with a fitting curve of
log-normal distribution. As seen in Fig. 3, thevariation of external dose can be described very wellby the log-normal distribution. Based on the
log-normal fitting, the 95 percentile point of the dose
distribution is calculated to be 2.92*(average dose),where 2.92 = 100.284*1.64. Values of 0.284 and 1.64 are
the standard deviation and the multiplying factor to
get the 95 percentile point, respectively.
Here it is assumed that the distribution of external
dose in Paryshev can be applied to other villages. It isalso assumed that the distribution of inhalation dose
has a wider deviation than that of external irradiationby two times, giving its 95 percentile point as
5.84*(average inhalation dose). Thus, 95 percentile
doses and percentages of inhabitants dose of which is
expected to exceed 1 Sv are calculated in fivesettlements in Table 2 and shown in Table 3.
Table 3 shows that substantial parts of inhabitants
at Krasnoe (18 %) and Usov (15 %) could receive
irradiation exceeding 1 Sv before their evacuation. At
Usov 159 persons were reportedly there at the time of

the accident [11], which means 25 persons exceeded 1
Sv.
Comparison with other evaluations
Estimates of collective external does for evacuees
from the 30-km zone are given in the 1986 USSR
report [1]. Those values are divided into groups ofsettlements dependent on the distance from the
Chernobyl site. Average external doses are calculated
and shown in Table 4. The average external dose of
24,200 people who were at 3 - 15 km at the time of
the accident is calculated to be 0.45 Sv, and that of
65,700 people at 15 - 30 km is 0.05 Sv. These doses
are consistent with our estimates shown in Table 3
although the 1986 report denied the occurrence of
ARS among inhabitants.
A comprehensive work on external dosereconstruction for evacuees was made by Ukrainianscientists, Likhtarev et.al. [11]. Based on thequestionnaires on daily behavior to 36,000 evacuees,
they reconstructed individual external dose of about
31,000 evacuees from the 30-km zone, including
about 14,000 in Pripyat city. The average and the
maximum external doses of the evacuees (excluding
the people in Pripyat) were evaluated to be 0.00182
Sv and 0.383 Sv, respectively. Based on theseestimates, it is difficult to suppose the occurrence of
ARS among inhabitants around the Chernobyl site.
Table 5 is a comparison of external dose between by
the present author and by Likhtarev et.al. Ourestimates are lager than those by Likhtarev et.al. by
Table 3 Dose value of 95 percentile and fraction of
inhabitants exceeding 1 Sv
Settlement
Usov
KrasnoeKryukiBorshchevka
Chernobyl

125

Average
total dose
（Sv）
0.44
0.48
0.28
0.13
0.02

95 percentile
(Sv)
1.65
1.79
1.04
0.47
0.09

Fractionexceeding 1 Sv
(%)
15
18
6
<1
∼0

about 3 times. The reason of the difference is Table 4 Average external dose of evacuees
unknown so far although the same values of shielding
reported in 1986 USSR reportfactors and dose conversion are used.
Distance from
Average
Number of Population
Several points should be mentioned about the
the Chernobyl
external dose
Settlement(persons)
work by Likhtarev et.al. At first, they excluded about
site
(Sv)
4,000 persons from their dose reconstruction with the
3 - 7 km
5
7,000
0.54
reason that they stayed in highly contaminated areas
7 - 10 km
4
9,000
0.46
10 15 km
10
8,200
0.35
or visited the Chernobyl station. Secondly, their work
15 - 20 km
16
11,6000.052
is mostly related to the territory of Ukraine. As seen
20 - 25 km
20
14,9000.060
in Fig. 1, highly contaminated areas extended to the
25
30
km
16
39,2000.046
north part of the 30-km zone, which belongs to
3
15
km
19
24,2000.45
Belarus.
15
30
km
52
65,7000.050
Conclusion
3 - 30 km
71
90,0000.16
Our findings are summaized as follows:! Maximum dose evaluated as the average inTable 5 Comparison of estimates of external dosesettlements do not reach 1 Sv of the criterion forby the present study and by Likhtarev
ARS.
et.al.
! Taking into consideration the distribution of
Average external dose (Sv)individual dose, substantial parts (15 to 20 %) of Settlement
A/B
Present
work (A)
Likhtarev (B)inhabitants in highly contaminated settlements are
Usov
0.32
0.118
2.7
evaluated to have received doses exceeding 1 Sv.
Chernobyl
0.018
0.0060
3.0! Our results agree with those presented in the 1986
USSR report, while our estimates are by about 3
1996.
times larger than those by Likhtarev et.al.
3.“Health Consequences of the Chernobyl Accident:! Our results are consistent with the information that
Results of the IPHECA Projects and Related National
there were a number of ARS cases among
Programmes”, WHO, 1995.
inhabitants around Chernobyl.
4.OECD/NEA, “Chernobyl: Ten Years on Radiologicaland Health Impact”, November 1995.
It should be noted that our estimation does not
5.A. Yaroshinskaya, IZVESTIYA, April 24, 1992.
include contributions of external dose from rare gases
6.A. Yaroshinskaya, “Chernobyl: Top Secret”,
and internal dose from ingestion. Negligence of these
Drugie-berega, Moscow, 1992.
paths does not mean they were negligible. It is simply
7.V.
Lupandin, Invisible Victims, NABAT 36, Minsk,
because they are difficult to be evaluated.
October
1992.
It is also noted that a typical case of ARS in the
8.I.K.Baliff and V.Stepanenko ed., “Retrospective
report of Lupandin is observed in village Borshchevka,
Dosimetry and Dose Reconstruction”, Experimantal
where ARS is difficult to be expected from ourCollaboration Project ECP-10. EUR 16540, EC, 1996.
estimation. This case can be considered to be
9.ECP-10, p17.
examples beyond the method of our estimation
10.Yu.A.Izrael, Chernobyl: Radioactive Contamination in
because the patient is reported to have stayed on thethe Environment, Gidrometizdat, 1990 (in Russian)dike of Pripyat river from April 26 to 27 for fishing.
11.I.A.Likhtalev et.al., “Retrospective Reconstruction of
Lupandin mentioned the possibility of a lot of such
Individual and Collective External Gamma Doses ofcases.
Population Evacuated after the Chernobyl Accident”,
Finally, we have to say that there are still a lot of
Health Physics, 66(6), (1994) 643-652.
questions that should be answered about the12.ECP-10, p109.
13.Yu.A.Izrael et.al., Meteorology and Hydrology, 1987
Chernobyl accident. For example, the authors have
No.2, pp.5-18 (in Russian).
one question for more than ten years. How much was
14.Yu.L.Dobrynin and P.B.Khramtsov, Radiation
the irradiation level that was received by young
Protection Dosimetry, 50 pp.307-10 (1993).
soldiers of the Chemical Troops of the Soviet Army
15.Reactor
Safety Study, WASH-1400 Draft, USAEC,
who arrived at Chernobyl on the next day of the1974.
accident and supposedly took part in the first works
16.Reactor Safety Study, WASH-1400, USNRC, 1975.
for liquidation in the atmosphere of several hundreds
17.K.Kawai et.al., Table of Committed Effective Doseof roentgen per hour?
References
1.USSR State Commission on the Utilization of Atomic
Energy, August 1986.
2.“One Decade after Chernobyl: Summing Up theConsequences of the Accident”, STI/PUB/1001, IAEA,

Equivalents According to the ICRP Publication 30,
JAERI-M 87-172 (1987)
18.ICRP Publication 60, 1990.
19.Bulletion of Ecological Situation of Evacuated Zone,
No.1 1996, Chernobyl-Interform (in Ukrainian).
20.ECP-10, p.25.

126