Atmospheric and Climate Sciences, 2011, 1, 100-112
doi:10.4236/acs.2011.13012 Published Online July 2011 (http://www.scirp.org/journal/acs)
Effect of Urbanization and Industrialization Processes on
Outdoor Thermal Human Comfort in Egypt
S. M. Robaa
Astronomy and Meteorology Department, Faculty of Science, Cairo University, Giza, Egypt
Received April 17, 2011; revised May 24, 2011; accepted June 7, 2011
Abstract
Detailed studies on the effect of urbanization and industrialization processes on outdoor thermal human com-
fort in Greater Cairo region, Egypt have been performed in this study. Four different districts in Greater
Cairo region have been selected to represent rural, suburban, typical urban and industrial areas. The data of
surface dry, wet bulb temperatures and wind speed for two different periods represent non-urbanized and
urbanized periods have been used. Discomfort indices for the two periods have been calculated for the four
districts. The study revealed that urbanization and industrialization processes have resulted in the distinctly
modification of human comfortable at all districts. The feeling of quite comfortable reduced from the old
non-urbanized period to the recent urbanized period at the four districts. During the recent urbanized period,
the rural area has the highest total number of quite comfortable hours while both urban and industrial areas
have the lowest total number of hours. The serious hot uncomfortable didn’t occur at all districts during the
old non-urbanized period while during the recent urbanized period, all people had felt extreme serious hot
uncomfortable only at urban and industrial areas. It could be concluded that the urbanization and industriali-
zation processes cause increase of human serious hot uncomfortable feeling which in turn leads to more hin-
dering for the human activities while the rural conditions leads to optimum weather comfort for further and
more human activities.
Keywords: Human Comfort, Urbanization, Industrialization, Greater Cairo Region, Egypt
1. Introduction
Whether discomfort is caused by either one of the factors
depend on the climatic conditions. The main meteorolo-
gical factors that largely influence the physiological sen-
sation of human comfort are temperature, humidity and
wind speed. Also, heavy rains and direct intensive inso-
lation could be causes of discomfort. A number of indi-
ces utilizing some of these factors have been proposed by
different authors, based on the physiological feeling of a
large number of people [1-13].
The thermal sensation of heat discomfort is experi-
enced under "steady state” conditions, when the average
skin temperature is elevated above the level correspond-
ing to the state of comfort. Under sedentary activity, it is
about 32 - 33˚C. The main environmental conditions,
which affect the thermal sensation of heat, are the air and
radiant temperatures, and the air velocity over the body.
The effect of air velocity on the thermal sensation de-
pends on the environmental temperature. At temperatures
below 32˚C, increasing air velocity reduces the heat sen-
sation due to the higher convective heat loss from the
body and lowering of the skin temperature. At tem-
peratures between about 33˚C and 37˚C air velocities
does not affect significantly the thermal sensation. At
environmental temperatures above 37˚C, increased air
velocity actually increases the thermal sensation of heat
[14]. Thermal sensation has two clearly defined limits.
The lower limit is attained when the skin is completely
dry and the upper limit is considered when the whole
body and clothing are soaked with sweat. Between these
two limits there are intermediate levels, which can be
defined quite clearly [15].
When the evaporation rates are much faster than sweat
Secretion the sweat evaporates as it emerges from the
pores of the skin, without forming a liquid layer over the
skin. The skin is then felt as dry. With increasing sweat
rate or decreasing rate of evaporation, sweat spreads over
the skin, increasing the effective area of evaporation
takes place. In this way the body can keep a rate of

S. M. ROBAA 101
evaporative potential to the environment. However, sub-
jectively the moist skin causes discomfort although it is
an essential ingredient in the physiological thermoregu-
lation. The rate of sweating is determined by the balance
between metabolic heat production and the heat loss by
convection and radiation. Under hot humid conditions
the cooling efficiency of sweating decreases, as part of
the sweat evaporates over hair and the clothing and de-
rives part of the energy from the ambient air instead of
from the body. The sweat rate and evaporation then ex-
ceed the need for evaporation cooling to compensate for
the reduced cooling efficiency.
Urbanization and industrialization processes have re-
sulted in the modification of local city climate [9] and
[16-29]. The urbanization and industrialization have in-
creased very rapidly in Greater Cairo region, particularly
in the last few years of the last century causing extreme
local climatic changes [9]. Therefore, the aims of this
study are to examine the effect of urbanization and in-
dustrialization processes on outdoor thermal comfort in
Greater Cairo region, Egypt. The results of this study are
useful for native people and as a guide to tourists or
visitors for understanding thermal comfort, planning out-
door recreational activities and developing the tourist
industry.
2. Methodolgy and Estimations
Siple and Passel [30] constructed chill index relates hu-
man feeling to the prevailing weather conditions (dry
temperature and wind speed); their index, K, is expressed
as follows;


d
K10 V +10.45-V33T



(1)
where, V is the wind speed (m/s) and Td is the dry tem-
perature (˚C) of surface air.
On the other hand, [31] studied the effects of tem-
perature and humidity on the human body. He deter-
mined a discomfort index, TI, using a simple linear ad-
justment applied to the average of the dry and wet bulb
temperatures readings;

dW
TI0.72 TT40.6 (2)
where Tw is wet bulb temperature in ˚C.
Also, the human feeling to the prevailing weather
conditions (dry temperature and relative humidity), MI,
could be calculated using the formula of [32];
 
dd
MIT0.4T10RH /100  (3)
where RH is the relative humidity in %.
The following comments could be concluded. Siple
and Passel’s index includes a considerable wind effect on
human comfort but the effect of humidity has not been
Table 1. Criterions of, RI, at different discomforts.
RI values Human feeling
RI < 60
60 ≤ RI < 65
65 ≤ RI < 75
75 ≤ RI < 80
80 ≤ RI < 85
85 ≤ RI
All people feel quite uncomfortable cooling.
50% of people feel partial uncomfortable cooling.
All people feel quite comfortable.
50% of people feel partially uncomfortable heat.
All people feel uncomfortable heat.
All people feel extreme serious uncomfortable heat.
Figure 1. Map of Greater Cairo Region, GCR (Study area)
(The rural, suburban, urban and areas are indicated).
considered. Furthermore, both Thom's and Missenard’s
indices do not include the effect of wind speed in spite of
its active role in assessing human comfort.
Therefore, Robaa [33] proposed formula accounting
for the combined effect of the three weather elements
(dry air temperature, humidity and wind speed) on hu-
man discomfort. His formula, RI, is expressed as fol-
lows;
dW
RI 1.53T0.32T1.38V 44.65

 (4)
The range of applicability of this formula (formula 4)
is wide and adequate for Egypt's climate. The criterions
of RI are given in Table 1.
Robaa [33] used RI (formula 4) and Table 1 to deter-
mine the thermal comfort and discomfort over the whole
Egypt country in daytime and nighttime of different
mon- ths of the year. He compared the obtained results of
RI with the results of Thom and Siple’s indices for the
same observations. He found that RI is closely related to
both Siple and Passel (Equation 1) and Thom (Equation
2) indices, however, RI, illustrates the integrated effect
of both wind speed and humidity in changes on human
comfortable. Many evidences have been performed to
illustrate that the proposed Robaa index, RI, gives pre-

102 S. M. ROBAA
Table 2. Coordinates and brief locations description.
Stations Lat.
(N)
Long.
(E) Brief description of their sites
Bahtim 30˚08' 31˚15'
An agrometeorological station, lies on the
border between urbanized and cultivated
area.
Cairo (A.
P.) 30˚08' 31˚24' Suburban site in the eastern desert.
Abbasiya 30˚05' 31˚17'
Typical urban site surrounded by overpopu-
lation towns in all directions except
SE-direction.
Helwan 29˚52' 31˚20' Heavy industrial site lies in south east of
Cairo City in eastern desert.
cise estimations for assessing human comfortable than
other discomfort indices [33].
This study examines the impacts of urbanization and
industrialization processes on thermal comfort in urban
Greater Cairo Region, GCR, Egypt. Therefore, four dif-
ferent districts in GCR, namely, Bahtim, Cairo Airport,
Abbasiya and Helwan have been chosen to represent
rural, suburban, urban and industrial area respectively
(Figure 1 and Table 2). RI index is used in this study to
determine the thermal comfort values over the above
four districts
3. Study Area
The study area of GCR lies in south of Delta of the Nile
basin. It is considered as one of the world’s 15 largest
cities in urban and population growth. Population in
GCR exceeds 18 millions concentrated over an area of
about 214 km2 (almost 4.2 km width and 50 km along
the sides of the River Nile). The urbanization and indus-
trialization have increased very rapidly in Greater Cairo,
particularly in the second half of the last century causing
an increase in the pollution of its atmosphere. This in
turn has an effective role in intensifying the problem of
contaminating Cairo’s environment with various impuri-
ties and environmental hazards [34].
Climatologically, GCR follows the subtropical cli-
matic region. It is characterized by the presence of Mo-
qattam hills to its east and south east, then desert areas
extending in the west and east directions. Among the
outstanding weather events are the dust and sandstorms
frequently blow in transitional seasons of spring (March
to May) and autumn (September to November). In spring,
hot desert depressions are known as the Khamsin depres-
sions. They are always associated with strong hot dry
wind often laden with dust and sand increasing the at-
mospheric pollution. In winter season (December to Feb-
ruary) the general climate of Greater Cairo region is cold,
moist and rainy while during summer season (Jun to
August), Cairo’s climate is hot, dry and rainless. Greater
Cairo region is composed of four main parts (Figure 1):
(1) The Shubra El-Kheima industrial complex area lies
at the northern boundary of Cairo City. Its area is about
30 km2 and over 550 industrial plants of various sizes.
Textile manufacturing is the predominant activity, fol-
lowed by engineering construction, chemical, petroleum
and electrical industries. Emissions from these industries
directly affect the air quality in the Central Cairo since it
is frequently upstream [35]. There has no any meteoro-
logical stations established at Shubra El-Kheima till now.
(2) The Central Cairo lies at the center on the east
bank of the River Nile. It accommodates more than 80%
of the area population and includes thousands of small
factories and workshops in addition to more than one and
half million of automobiles travelling on the city roads.
(3) A narrow strip of Giza Governorate runs along the
western side of the River Nile, opposite to the Central
Cairo. This sector has two mains, but small, industrial
centers: one in the northern part of the strip and other in
the south. Residential districts lie between both industrial
centers.
(4) The heavy industry area of Helwan, is about 24 km
to the south east of the Central Cairo.
A brief description and basic information of the four
selected districts (Figure 1 and Table 2) are given be-
low;
Bahtim agrometeorological station lies about 13 km to
the north west of Central Cairo near the border between
urbanized and cultivated area. It has been established at
the end of 1966 in the field of the Agricultural Research
Station of the Agricultural Society at Bahtim and is
working on routing basis up till now (2011). The obser-
vational field at Bahtim included a dry and bare field up
to 1970. Afterwards it included a wet field covered with
grass (Lippa-Nodiflora). The surrounding area was cul-
tivated land and it was considered to be a good example
of the rural area. The irrigation in Bahtim in addition to
the Nile water is considered important and good moisture
sources. Fortunately, although the population and human
activities started increasing rapidly nearby Bahtim area
during the last few last years, its typical rural conditions
is still completely existing until now (2011).
The international Cairo Airport lies about 29 km to the
north east border of Central Cairo in the eastern desert.
The Airport is surrounded by the desert from all its di-
rections except the southwest direction where the loca-
tion of Central Cairo and Abbasiya urban area. There is a
very vast open area around Airport runway. There are no
any buildings or human activities around the Airport and
a shortest distance between the nearest buildings and
Airport place is not less than 12 km. Much of asphalt
roads and the associated traffics exist around the Airport
to connect it by the surrounding countries. The local soil
of the Airport is originally desert sand and there has no
any moisture sources at Airport location.

S. M. ROBAA 103
Abbasiya meteorological station (main building of the
Egyptian Meteorological Authority, EMA) lies on the
east bank of the River Nile near Central Cairo on the
road leading from the city to the suburb of Heliopolis, to
the northeast part of Cairo city. Much of factories exist in
the nearby area also, where high density of buildings and
high density of population exists in addition to thousands
cars and buses. Streets are covered by asphalt and gar-
dens are not abundant. The local soil is originally desert
sand. There have no any moisture sources except River
Nile. Generally, air quality in Abbasiya station represents
the typical urbanization occurs in and around Cairo City.
Helwan is the heavy industry area, is about 24 km to
the south east of the city of Cairo. The most important
factors in this area are the steel, cement, chemical, fertil-
izer, brick and car industries and power plants. Before
1970, this city was an international famous calm place
distinguished by its fine and good weather as well as its
known natural spring. Peoples from different parts of the
country and from different countries usually visited it
enjoyed its good weather and exposing themselves to the
beneficial solar radiation. From 1970, industrialization
has been growing very rapid in and around Helwan.
Therefore a significant variation of surface air tempera-
tures, relative humidity and other meteorological ele-
ments causes increase of the green house effect as a re-
sult of increase air pollution [36]. These industrial proc-
esses cause decrease of wind speed and increase of at-
mospheric heating over Helwan especially in summer
months. This is due to sharp increase of aerosols and
gaseous pollutants in Helwan’s atmosphere from both
natural and industrial sources [9].
All the above stations were adequately and regularly
serviced by EMA.
4. Data Used
The available monthly mean daily values of measured Td,
Tw (˚C) and V (m/s), at eight fixed hours (0000, 0300,
0600, 0900, 1200, 1500, 1800 and 2100 GMT) for non-
urbanized periods (1967-1976) and (1947-1956) at
Bahtim and other three districts respectively and for re-
cent urbanized period (1990-2009) at the four districts
have been taken from EMA and used in this study.
Hourly mean discomfort index for all year months has
been calculated for the four districts applying Robaa’s
discomfort index, RI, (Equation 4). Results are given as
isopleths in Figures 5 and 6. Six ranges of discomfort
index are considered corresponding to values; RI < 60,
60 ≤ RI < 65, 65 ≤ RI < 75, 75 ≤ RI < 80, 80 ≤ RI < 85
and 85 ≤ RI (Table 1). The number of hours of discom-
fort index in each of the above ranges in each month of
the two periods at the mentioned districts are given in
Tables 3-7. Also, the monthly mean values of dry air
temperature, Td (˚C), relative humidity, RH (%) and
wind speed, V (kt) at the four selected stations for the
recent urbanized period (1990-2009) have been used and
presented in Figures 2-4 to give an idea of how local
surface conditions modify the microclimates. These data
were also obtained from EMA.
5. Results and Discussion
5.1. The Annual Variation of Td
Figure 2 illustrates that monthly mean dry temperature,
Td, rises at the four understudy stations (Bahtim, Cairo
Airport, Abbasyia and Helwan) very regularly from low
values during winter season to high values in summer
season. The coldest month during the considered period
is January while the hottest month is August at the four
different locations (Figure 2).
It could be noticed that monthly mean dry temperature,
Td, values at the industrial area (Helwan) are always
greater than urban (Abbasyia), suburban (Cairo Airport)
and rural (Bahtim) areas with higher values of urban than
rural area during all months (Figure 2). The greater Td
values at the industrial area is due to the heavy industrial
collection at Helwan and highly polluted air causing
green house effect leading to rising surface air tempera-
ture during all months of the year [12].
Also, it could be noticed that the Td values of the ur-
ban area are closest to the values of industrial area during
all year months. This is attributed to high concentration
of smoke and aerosols in Abbasiya’s atmosphere result-
ing from more than 2 millions cars and buses moving in
its streets, in addition to increase of industries in a big in-
dustrial activity area of Shubra-El Kheima (lies at the
Figure 2. Annual variation of mean temperature, Td (˚C) at
the industrial, urban, suburban and rural areas in GCR
during the period (1990-2009).

104 S. M. ROBAA
northern boundary of Abbasiya). The main industries are
textiles, fertilizer, and power stations.
On the other hand, Bahtim has the lowest values of Td
among all stations in all months of the year. This is due
to it is rural site and dominated by vegetations and lack
of pollution sources. Because Cairo Airport is suburban
site, it has Td values higher than Bahtim and lower than
both Abbasiya and Helwan for all months of study period
(1990-2009).
The differences between the values of Td for all sta-
tions are distinctly larger in summer months than at any
other time of the year. These differences are very large
between Bahtim and remain three stations. This is attrib-
uted to both artificial heats resulting from urbanization
and industrialization processes and high temperature of
summer season causing more rising in temperature over
urban areas. Otherwise, the absences of artificial heat at
rural area of Bahtim in addition to its rural characteristics
cause relative decrease in its temperature.
5.2. The Annual Variation of
Relative Humidity (RH%)
Figure 3 illustrates the characteristic features of the
mean annual variation of RH% at the four understudy
stations during the period (1990-2009). Minimum value
attained in May and maximum value is found in January
at all stations. This is as expected given the inverse rela-
tionship between relative humidity and air temperature
(See Figures 2-3). Also, it was found that Bahtim has
higher values of RH% than other stations during all
months of the year. This is attributed to evapotranspira-
tion form trees, great area of plants and other vegetation
existing in Bahtim area as well as increases evaporation
processes form irrigated wide fields. However, Helwan
has lower value of RH% compared with other stations
during all months of the year. This is due to distinctly
Figure 3. The same as Figure 2, but for relative humidity
RH%.
reduced areas of vegetation and water surfaces, which
replaced by many factors and heavy industries at Helwan
recently. This is in agreement with Oguntoyinbo [20],
who had shown that RH% is lower in the city center than
in the rural suburbs. Both urban and suburban areas have
relative humidity values lower than rural values and
higher than industrial area with higher values of urban
values.
The industrial, urban, suburban and rural areas have
their minimum relative humidity values during May
month. This is may be attributed to Khamsin depressions
that are more common during spring season over Egypt.
These depressions are characterized by strong hot and
dry winds that distinctly cause decreasing the amount of
water vapour content and increasing the dust content in
the lower layers of the atmosphere [37].
It is also noticed that the temporal pattern in the rela-
tive humidity differences is reverse to the temporal pat-
tern of the temperature differences between the men-
tioned stations, with minimum and maximum of relative
humidity values coincident with maximum and minimum
of the air temperature values. This means that relative
humidity is a sensitive function of temperature and the
urban-suburban/rural differences are strongly affected by
the degree of urbanization [28,38-41].
5.3. The Annual Variation of Wind Speed (Kt)
Figure 4 shows the monthly mean wind speed (kt) of the
four stations. It could be noticed that mean wind speed
values at the suburban area are always greater than urban
and rural areas with higher values of rural than urban
area during all months (Figure 4). The greater wind at
the suburban area is due to a vast open area around the
runway of the Airport. The lower wind at the urban area
is may be attributed to the fact that wind speeds are gen-
erally lower in the built up areas than in their surround-
Figure 4. The same as figure 2, but for wind speed (kt).

S. M. ROBAA 105
Table 3. Number of hours of very cold (RI < 60) in each month of both non-urbanized and urbanized periods at the four
study districts.
Bahtim Cairo A.P. Abbasiya Helwan
1967-1976 1990-2009 1947-1956 1990-2009 1947-1956 1990-2009 1947-1956 1990-2009
Jan 744 652 654 474 654 474 654 564
Feb 510 510 582 402 492 312 492 402
Mar 464 392 474 384 474 180 474 204
Apr 180 0 180 0 90 0 90 0
May 0 0 0 0 0 0 0 0
Jun 0 0 0 0 0 0 0 0
Jul 0 0 0 0 0 0 0 0
Aug 0 0 0 0 0 0 0 0
Sep 0 0 0 0 0 0 0 0
Oct 0 180 0 0 0 0 0 0
Nov 180 270 180 0 180 0 180 0
Dec 474 364 474 384 474 90 474 282
Total 2552 2368 2544 1644 2364 1056 2364 1452
Figure 5. Human comfort index, RI, during the old non-urbanized period at (a) Rural area of Bahtim, (b) suburban area of
Cairo A.P., (c) Typical urban area of Abbasiya, (d) Industrial area of Helwan.
ing country resulting from the increase in surface rough-
ness within cities [19] and [42]. The urban, suburban and
rural areas have their maximum wind speed during May
month. This is may be attributed to the effect of Khamsin

106 S. M. ROBAA
depressions that are more common during spring season
over Egypt, as mentioned above.
5.4. Thermal Human Comfort at the
Rural Area of Bahtim
It was found that, all people at the rural area of Bahtim
feel quite uncomfortable due to cold weather (RI < 60)
during six months (November to April) of the old
non-urbanized period (1967-1976) reduced to only four
months (December to March) during the recent urban-
ized period (1990-2009) (Table 3 and Figures 5(a)-6(a)).
This is attributed to increase of air temperature resulting
to urbanization and industrialization, which occur, re-
cently around study area of Bahtim [9] and [12].
It is also noticed that January month has maximum
number of quite uncomfortable cooling hours (RI < 60)
through both study periods with greater value of the old
period by 182 hours (Table 3). This is attributed to the
northerly cold air invades Egypt during this month in
addition to reduction of air temperatures due to the ther-
mal radiant emittance during the long night hours in the
course of diurnal variation. April and December months
have minimum number of quite uncomfortable cooling
hours during old (91 hours) and recent period (365 hours)
respectively. Furthermore, the total number of quite (RI
< 60) and partial uncomfortable cooling (60 ≤ RI < 65)
hours in non-urbanized period is distinctly higher than its
corresponding hours of urbanized period (Table 3 and
Figures 5(a) - 6(a)). This is due, as mentioned above, to
recently air temperature increase and decrease of both
relative humidity and wind speed at Bahtim [9] and [12].
On the other hand, during the both study periods, all
people in Bahtim feel quite comfortable (65 ≤ RI < 75) in
most months of the year with hours number differs from
month to another (Table 3). However, it was noticed that
the two months of December and March transformed
from cold uncomfortable months during the old
non-urbanized period to quite comfortable months for all
people during the recent urbanized period. These two
months (December and March) have 182 hours of quite
comfortable during the recent urbanized period instead of
0 hours during the old non-urbanized period. Further-
more, it was found that the total number of quite com-
fortable hours in old non-urbanized period (4106 hours)
is distinctly higher than its corresponding hours of recent
urbanized period (3558 hours). This means that all peo-
ple in the rural area of Bahtim had felt quite comfortable
about 6 months through the year before the urbanization
processes started around Bahtim area reduced to about 5
months through the recent urbanized period (Table 3).
It was also found that, all total number of hot discom-
fort hours for 50% of the rural area people (75 ≤ RI < 80)
during the recent urbanized period (1990-2009) is higher
by 1277 hours than the old non-urbanized period
(1967-1976). Furthermore, the discomfort index did not
exceed 80 during any month of the two study periods,
except July of the recent period where it has only 183
hour of hot discomfort for all people of Bahtim (Table 3
and Figures 5(a)-6(a)). This is may be attributed to rural
conditions of Bahtim area.
5.5. Thermal Human Comfort at the
Suburban Area of Cairo Airport
It was found that all people in suburban area of Cairo
Airport feel quite uncomfortable cooling, (RI < 60), dur-
ing five months (November to March) during the
non-urbanized period (1947-1956) reduced to only four
months (December to March) during the recent urban-
ized period (1990-2009). (Table 3 and Figures 5b-6b).
This is due to increase of air temperature resulting from
recently severe suburban conditions of airport [9].
It was noticed that, as occurred at rural area, January
month has maximum number of quite uncomfortable
cooling hours (RI < 60) through both study periods with
greater value of the old period by 182 hours (Table 3).
While November and December months have minimum
number of quite uncomfortable cooling hours (91 hours
for November and 364 hours for December) through the
old and recent periods respectively. Furthermore, the
total number of quite (RI < 60) and partial uncomfortable
cooling (60 ≤ RI < 65) hours in non-urbanized period is
distinctly higher than its corresponding hours of the re-
cent urbanized period (Tables 3-4 and Figures 5(b) &
6(b)).
On the other hand, during both study periods, all peo-
ple in Cairo Airport feel quite comfortable (65 ≤ RI < 75),
in most months of the year with hours number differs
from month to another (Table 5). Both cold months of
December and March, exactly as occurred at rural area,
transformed from cold uncomfortable months during the
old period to comfortable months for all Cairo Airport
people during the recent urbanized period. These two
months have 182 hours of quite comfortable during the
recent period instead of 0 hours during the old period
(Table 5). Furthermore, the total number of quite com-
fortable hours in non-urbanized period (4106 hours) is
distinctly higher than its corresponding hours of urban-
ized period (3376 hours). This means that all people in
Cairo Airport area had felt quite comfortable about 6
months through the year before urbanization processes
started (i.e., during 1947-1956), reduced to about 4.5
months through the recent period (1990-2009). This
could be attributed to increase of air temperature and
ecrease of both wind speed and relative humidity in- d

S. M. ROBAA 107
Table 4. Number of hours of cold (60 ≤ RI < 65) in each month of both non-urbanized and urbanized periods at the four
study districts.
Bahtim Cairo A.P Abbasiya Helwan
1967-1976 1990-2009 1947-1956 1990-2009 1947-1956 1990-2009 1947-1956 1990-2009
Jan 0 92 90 270 90 180 90 90
Feb 162 162 90 270 180 90 180 90
Mar 190 190 270 180 270 282 180 270
Apr 270 270 180 270 180 0 270 0
May 270 190 270 90 180 90 180 0
Jun 90 0 0 0 0 0 0 0
Jul 0 0 0 0 0 0 0 0
Aug 0 0 0 0 0 0 0 0
Sep 0 0 0 0 0 0 0 0
Oct 270 162 180 0 180 0 180 0
Nov 270 180 270 360 270 180 270 90
Dec 270 290 270 180 270 384 270 180
Total 1792 1536 1620 1620 1620 1206 1620 720
Table 5. Number of hours of quite comfortable (65 ≤ RI < 75) in each month of both non-urbanized and urbanized periods at
the four study districts.
Bahtim Cairo A.P Abbasiya Helwan
1967-1976 1990-2009 1947-1956 1990-2009 1947-1956 1990-2009 1947-1956 1990-2009
Jan 0 0 0 0 0 90 0 90
Feb 0 0 0 0 0 270 0 180
Mar 90 162 0 180 0 282 90 270
Apr 270 450 360 360 450 450 360 450
May 474 364 474 384 564 384 474 372
Jun 630 360 630 360 540 180 450 180
Jul 564 190 564 180 564 0 474 0
Aug 744 372 654 270 564 0 564 0
Sep 720 450 720 450 630 270 450 180
Oct 474 402 564 654 564 474 564 474
Nov 270 270 270 360 270 450 270 540
Dec 0 90 0 180 0 270 0 282
Total 4236 3110 4236 3378 4146 3120 3696 3018
duced by urbanization process that recently occurred at
airport area [9] and [12].
It was also found that, all total number of partial un-
comfortable heat (75 ≤ RI < 80) hours for the recent pe-
riod (1990-2009) is higher by 1095 hours than the
non-urbanized period (1947-1956). In addition, discom-
fort index did not exceed 80 during any month of the
non-urbanized period, but the hot uncomfortable (80 <
RI < 85) for all people of Cairo Airport started by grow-
ing of urbanization through the last few decades. There
are 548 hours of hot uncomfortable occurred during the
daytime of three months (June to August) especially
around local noon as shown in Figure 6(b) and Table 7.
Fortunately, the discomfort index did not exceed 85 dur-
ing any month of the both study periods at Cairo Airport.
5.6. Thermal Human Comfort at
the Urban Area of Abbasiya
It was found that all people in urban area of Abbasiya
feel quite uncomfortable cooling (RI < 60) during only
four cold months (December to March) during the
non-urbanized period (1947-1956) reduced to only three
months (January to March) during the recent urbanized
period (1990-2009) (Table 3 and Figures (5) & (6)).
This is attributed to distinctly increase of air temperature
and decrease of both wind speed and relative humidity
induced by urbanization process that recently occurred in
and around urban area of Abbasiya [9] and [12].
It is also noticed that, as occurred at the rural and subur-
ban areas, January month has maximum number of quite
uncomfortable cooling hours (RI < 60) through both
study periods (730 and 365 hours for the old and recent
period respectively) with twice greater value of the old
period (Table 3). While December and March months
have minimum number of quite uncomfortable cooling
hours (456 hours for both months) through the old period
while the minimum hour number of the recent period (91
hours) occurred in March. Furthermore, the total number
of quite (RI < 60) and partial uncomfortable cooling (60
≤ RI < 65) hours in non-urbanized period is distinctly
higher than its corresponding hours of the recent urban-
ized period (Tables 3 & 4 and Figures 5© & 6(c)).
On the other hand, during the two study periods, all
people in Abbasiya feel quite comfortable (65 ≤ RI < 75)
n most months of the year with hours number differs i

S. M. ROBAA 108
Figure 6. Human comfort index, RI, during the recent urbanized period at (a) Rural area of Bahtim, (b) Suburban area of
Cairo A.P., (c) Typical urban area of Abbasiya, (d) Industrial area of Helwan.
from month to another. However, it was noticed that the
three cold months (December, February and March)
transformed from cold uncomfortable months during the
old non-urbanized period to comfortable months for all
Abbasiya’s people during the recent urbanized period
(Table 5). These three months have 639 hours of quite
comfortable during the recent period instead of 0 hours
during the old period. Reversely, the two hot months
(June and July) transformed from comfortable months
for all Abbasiya’s people during the old non-urbanized
period to uncomfortable heat months during the recent
urbanized period. They have 913 hours of quite com-
fortable during the old period instead of 0 hours during
the recent period. This is due to the extreme local cli-
matic changes induced by rapid growth of urbanization
processes in Abbasiya. Furthermore, the total number of
quite comfortable hours (65 ≤ RI < 75) in non-urbanized
period (4015 hours) is distinctly higher than its corre-
sponding hours of urbanized period (3103 hours). This
means that all people in Abbasiya had felt comfortable
more than 5.5 months through the years before urbaniza-
tion processes started reduced to about 4 months only
through the recent urbanized period (Table 5).
It was also found that, all total number of partial un-
comfortable heat (75 ≤ RI < 80) hours for the recent pe-
riod (1990-2009) is higher by 1460 hours than the
non-urbanized period (1947-1956) (Table 6). In addition,
discomfort index did not exceed 80 during any month of
the non-urbanized period (Table 7), while by growing of
urbanization in the recent years represented by the period
(1990-2009), the hot uncomfortable feeling started for all
Abbasiya’s people. There are 1186 hours of hot (80 ≤ RI
< 85) and extreme hot uncomfortable (RI ≥ 85) for all
people of Abbasiya (820 and 366 hours for hot and ex-
treme serious hot uncomfortable respectively) occurred
uring the daytime only i.e., more than 1.5 months of d

S. M. ROBAA 109
Table 6. Number of hours of hot uncomfortable for 50% of people (75 ≤ RI < 80) in each month of both non-urbanized and
urbanized periods at the four study districts.
Bahtim Cairo A.P. Abbasiya Helwan
1967-1976 1990-2009 1947-1956 1990-2009 1947-1956 1990-2009 1947-1956 1990-2009
Jan 0 0 0 0 0 0 0 0
Feb 0 0 0 0 0 0 0 0
Mar 0 0 0 0 0 0 0 0
Apr 0 0 0 90 0 270 0 270
May 0 190 0 270 0 270 90 372
Jun 0 360 90 360 180 360 270 360
Jul 180 554 180 564 180 564 270 564
Aug 0 372 90 474 180 654 180 654
Sep 0 270 0 270 90 450 270 540
Oct 0 0 0 90 0 270 0 270
Nov 0 0 0 0 0 90 0 90
Dec 0 0 0 0 0 0 0 0
Total 180 1746 360 2118 630 2928 1080 3120
Table 7. Number of hours of hot uncomfortable for all people (80 ≤ RI < 85) in each month of both non-urbanized and ur-
banized periods at the four study districts.
Bahtim Cairo A.P Abbasiya Helwan
1967-1976 1990-2009 1947-1956 1990-2009 1947-1956 1990-2009 1947-1956 1990-2009
Jan 0 0 0 0 0 0 0 0
Feb 0 0 0 0 0 0 0 0
Mar 0 0 0 0 0 0 0 0
Apr 0 0 0 0 0 0 0 0
May 0 0 0 0 0 0 0 0
Jun 0 0 0 0 0 180 0 180
Jul 0 0 0 0 0 180 0 180
Aug 0 0 0 0 0 90 0 90
Sep 0 0 0 0 0 0 0 0
Oct 0 0 0 0 0 0 0 0
Nov 0 0 0 0 0 0 0 0
Dec 0 0 0 0 0 0 0 0
Total 0 0 0 0 0 450 0 450
people of Abbasiya (820 and 366 hours for hot and ex-
treme serious hot uncomfortable respectively) occurred
during the daytime only i.e., more than 1.5 months of
continuous hot and extreme hot discomfort started by
June and ended by September especially around local
noon as shown in Figure 6 (c) and Tables 7.
5.7. Thermal Human Comfort at
the Industrial Area of Helwan
All people in the industrial area of Helwan feel quite
uncomfortable due to cold weather (RI < 60) only during
four months (December to March) of both study periods.
It was found that the total number of quite (RI < 60) and
partial (60 ≤ RI < 65) cold uncomfortable hours during
the non-urbanized period (1947-1956) is higher than
their corresponding hours in the recent period (1990-
2009), (Table 3 and Figures 5(d) & 6(d)). This is attrib-
uted to distinctly increase of air temperature and de-
crease of both wind speed and relative humidity induced
by complex industrial processes that recently occurred at
the industrial area of Helwan [9] and [12].
On the other hand, during both study periods, all peo-
ple in Helwan City feel quite comfortable (65 ≤ RI < 75)
in most months of the year with hours number distinctly
differs from month to another (Table 5). However, it was
noticed that the cold months, (December to March)
transformed from cold uncomfortable season during the
old non-industrial period to quite comfortable season for
all Helwan’s people during the recent industrial period.
This season has 913 hours of quite comfortable during
the recent period instead of 0 hours during the old period.
Reversely, the three hot months (July - September)
transformed from quite comfortable months for all Hel-
wan’s people during the old non-industrial period to hot
and extreme serious hot uncomfortable months during
the recent industrial period. These months have 1369
hours of quite comfortable during the old period instead
of 0 hours during the recent period. Furthermore, the
total number of quite comfortable hours (65 ≤ RI < 75) in
non-industrial period (1947-1956) (3833 hours) is dis-
tinctly higher than its corresponding hours of industrial
period (1990-2009) (3103 hours). This means that all
people in Helwan had felt comfortable about 5.5 months
through the years before industrialization processes
started at Helwan (i.e., during 1947-1956), reduced to

110 S. M. ROBAA
about 4 months only through the recent period (1990-
2009).
It was also found that, all total number of partial un-
comfortable heat (75 ≤ RI < 80) hours for the recent pe-
riod (1990-2009) is higher by 912 hours than the
non-urbanized period (1947-1956) (Table 6). Further-
more, discomfort index did not exceed 80 during any
month of the non-urbanized period (Table 7), while by
growing of the industrialization processes in the recent
years, the hot uncomfortable feeling started for all Hel-
wan’s people. There are 1735 hours of hot (80 ≤ RI < 85)
and extreme serious hot uncomfortable (RI ≥ 85) for all
Helwan’s people (1369 and 366 hours for hot and ex-
treme serious hot uncomfortable respectively) occurred
during the daytime only i.e., more than 2.5 months of
continuous hot and extreme hot discomfort started by
May and ended by September especially around local
noon as shown in Figure 6(d) and Tables 7.
5.8. Urban-Suburban/Rural Human
Comfort in Greater Cairo
It was found that all people in rural, urban, suburban and
industrial areas feel quite uncomfortable due to cold
weather (RI < 60) during only four months (December to
March) of both study periods exception rural area
through the old non-urbanized period (Table 3). January
month has maximum number of quite uncomfortable
cooling hours through both study periods with greater
value of the old period at all districts. This is attributed,
as mentioned above, to the northerly cold air invades
Egypt during this month as well as the reduction of air
temperatures due to the thermal radiant emittance during
the long night hours of this month. On the other hand, the
total number of quite uncomfortable cooling (RI < 60)
hours in rural area is higher than its corresponding hours
in urban, suburban and industrial areas during both study
periods except the suburban area (Table 3). This is due
to rural conditions at Bahtim [9] and [12]. While the ur-
ban area of Abbasiya has the lowest number of quite
uncomfortable cooling (RI < 60) hours during both study
periods with distinctly higher total number of hours dur-
ing the old non-urbanized period. This is due to high
temperature and low values of both wind speed and rela-
tive humidity resulting from severe urban conditions at
Abbasiya [9] and [12]. It must be noticed that the differ-
ence between the highest (at rural area) and lowest (at
urban area) total number of quite uncomfortable cooling
hours during the old non-urbanized period (274 hours) is
distinctly lower than its corresponding hours during the
recent urbanized period (1095 hours). This explains the
increase of urbanization effects from the old to recent
period especially at the urban area of Abbasiya. It is clear
that the total number of quite and partial cold uncom-
fortable hours gradually decrease with the increase of
urbanization degree. Furthermore, the partial uncom-
fortable cooling feeling (60 ≤ RI < 65) has similar char-
acteristics of quite uncomfortable cooling (RI < 60) at all
districts.
During the old non-urbanized period, both rural and
suburban areas have the highest total number of quite
comfortable (65 ≤ RI < 75) hours (4106 hour) while the
industrial area of Helwan has the lowest total number of
hours (3833 hours) (Table 5). The equivalence of the
total number of quite comfortable hours for rural and
suburban areas is may be due to the time lag of the old
un-urbanized at rural (1967 - 1976) and suburban (1947 -
1956) areas. During the recent urbanized period (1990 -
2009), the rural area has also the highest total number of
quite comfortable hours (3558 hour) while both urban
and industrial areas have the lowest total number of
hours (3103 hours). This is due to rural conditions at
Bahtim and higher air temperature at urban and industrial
areas resulting from artificial heat [9] and [12], (Table 5
and Figures 5-6). It must be also noticed that the differ-
ence between the highest and lowest total number of
quite comfortable hours during the old non-urbanized
period (273 hours) is lower than its corresponding hours
during the recent urbanized period (455 hours). This
means that all districts are nearly characterize by rela-
tively similar clear weather during the old period, but
with the recently urbanization growth, its effects gradu-
ally increase from old to recent period to reach its maxi-
mum effect during last few years especially at urban and
industrial areas.
Discomfort index did not exceed 80 during both study
periods at the rural area exception July month of the re-
cent urbanized period whereas Bahtim has 183 hours (the
lowest total number hours) of hot uncomfortable (80 ≤
RI < 85) for all people (Tables 6-7 and Figures
5(a)-6(a )). This is attributed to rural and open area of
Bahtim.
On the other hand, both industrial and urban areas
have the largest total number of partially hot uncomfort-
able (75 ≤ RI < 80) hours (1004 and 2190 hours for in-
dustrial and urban areas respectively) during the old and
recent period respectively (Table 6). When RI is in the
range 80 - 85, everyone is expected to be uncomfortable
and it becomes serious at the higher values. The num-
ber of hours in all months of the year when RI is greater
than 80 are given in Tables 7. It was found that the num-
ber of 80 ≤ RI < 85 hours agrees with the degree of ur-
banization of every station. Therefore, industrial area has
the maximum number of RI > 80 hours (1369 hours)
followed it directly, the urban area (821 hours) (Table 7).
This is due to more population and rapidly increase of

S. M. ROBAA 111
urbanization and industrialization processes at their ar-
eas.
When the value of discomfort index, RI, passes above
85, discomforting becomes more serious. If the office
conditions in the Washington metropolitan area are such
that the index becomes 86 or higher, Government regu-
lations permit mass dismissal of employees who are
working under these conditions [1].
From the Egyptian data considered in this paper, it is
observed that the value of RI exceeds 85 only at urban
and industrial areas during the summer months (July -
August). It could be noticed that the serious hot discom-
fort (85 ≤ RI) didn’t occur at all districts during the old
non-urbanized period while during the recent urbanized
period, both urban and industrial areas have values of RI
exceeds 85 (366 hours for both them) during July and
August and they occur afternoon (Figures 5-6). This is
attributed to this time interval has maximum concentra-
tion of traffic and go out of thousands employees in ad-
dition to the giant and rapidly increase of industrializa-
tion processes at Helwan area. It was found that serious
hot discomfort (85 ≤ RI) didn’t occur at both rural and
suburban areas during the two study periods.
6. Conclusions
Detailed studies on the effect of urbanization and indus-
trialization on human comfort in Greater Cairo region,
Egypt have been performed in this study. Four different
districts in Greater Cairo region have been selected,
namely Bahtim to represent rural area, Cairo Airport
to represent suburban area, Abbasiya to represent typi-
cal urban area and Helwan to represent industrial area.
The data of surface dry, wet bulb temperatures and wind
speed for two different periods have been used. The first
period (1967-1976 and 1947-1956 for the rural and re-
main three districts respectively) represents the old
non-urbanized period while the second period
(1990-2009 for all districts) represents the recent urban-
ized period. Discomfort indices for the two periods have
been calculated using Robaa's formula 4. The study re-
vealed that urbanization and industrialization processes
have resulted in the modification of local city climate.
This modification involves the alteration of the local air
temperature, humidity and wind speed which in turn
cause human climate change. It could be concluded that
the urbanization and industrialization processes at any
locality cause increase of human serious hot uncomfort-
able feeling which in turn leads to more hindering for the
human activities while the rural conditions leads to op-
timum weather comfort for further and more human ac-
tivities.
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