Journal of Environmental Protection, 2011, 2, 72-75
doi:10.4236/jep.2011.21007 Published Online March 2011 (http://www.SciRP.org/journal/jep)
Higher Temperatures Were Closely Associated
with Higher Ambulance Transports in Takamatsu
Area, Japan
Nobuyuki Miyatake1, Masaki Nakao2, Noriko Sakano1, Shigeru Suna3, Takeshi Suzue4,
Tomohiro Hirao4
1Department of Hygiene, Faculty of Medicine, Kagawa University, Miki, Kagawa, Japan; 2Graduate School of Engineering, Osaka
City University, Osaka, Japan; 3Kagawa Prefectural College of Health Sciences, Japan; 4Department of Public Health, Faculty of
Medicine, Kagawa University, Miki, Kagawa, Japan.
Received October 22nd, 2010; revised December 9th, 2010; accepted January 17th, 2011.
ABSTRACT
The link between high temperatures and ambulance transports in Takamatsu area, Japan was investigated. Monthly
observations for ambulance transports (2004-2008) were obtained from Fire Department Service in Takamatsu. Data
of temperatures in Takamatsu area, Japan (2004-2008) were used by Japan Meteorological Agency. Effect of high
temperatures on ambulance transports was analyzed. By using data from July to September, there were not clear dif-
ferences of mean temperatures and ambulance transports among years. Ambulance transports were significantly cor-
related with parameters of temperatures. Correlation coefficient rate between ambulance transports and the mean
temperature of maximum temperatures in a month was highest among parameters (r = 0.738, p = 0.0017). In add ition,
ambulance transports were also significantly correlated with the number of days over the level of 32˚C in a month (r =
0.782, p = 0.0006). Higher temperatures were closely associated with higher ambulance transports in Takamatsu area,
Japan.
Keywords: Te mperature, Ambulance Transports, Takamatsu Area, Fire Department Service in Takamatsu, Japan
Meteorological Agency
1. Introduction
Global average temperatures are projected to increase
between 1.4 and 5.8˚C by the end of this century [1]. On
local and regional scales, changes in land cover can
sometimes exacerbate the effect of greenhouse-gas-in-
duced warming, or even exert the largest impact on cli-
matic conditions. Most cities show a large heat island
effect, registering 5-11˚C warmer than surrounding rural
areas [2]. An increase in mortality related to heat waves
has been reported from various industrialized countries
[3-5].
The number of patients with heat stroke is surveyed by
National Institute for Environmental Studies in several
cities, except Takamatsu area, in Japan [6]. An increase
in summer temperatures is likely to increase the number
of patients with high temperatures related diseases.
Therefore, it is timely to assess local evidence of acute
health effects of high temperatures in Takamatsu area,
Japan.
In this study, to address this issue, we investigated
monthly ambulance use and its relation to high tempera-
tures in 5 summers in Takamatsu area, Japan.
2. Methods
2.1. Study Area
Takamatsu area, Kagawa prefecture, Japan, which in-
cludes Takamatsu city, Miki-cho and Ayagawa-cho, is on
the northern shor e of Shikoku Is land ( in a temperate zo n e
area). The populatio n of Kagawa prefecture is 1 000 000
and 470 000 people are situated on the Takamatsu area.
Currently several public offices of Shikoku district are
located in Takamatsu city. Although the surrounds of
Takamatsu had been used primarily as paddy fields for
agriculture, recently they have undergone rapid changes,
developing into residential and/or commercial areas. The
area’s emergency medical services are managed by Fire

Higher Temperatures Were Closely Associated with Higher Ambulance Transports in Takamatsu Area, Japan73
Department Service in Takamatsu and 14 ambulances
were in use in 2008 [7].
2.2. Ambulance Data
Monthly incidence data of ambulance transports was
obtained from Fire Department Service in Takamatsu
from July to September for 5 years (2004-2008) [7]. We
excluded the number of other ambulance transports i.e.
traffic accidents, fire accidents and injuries, and the
number of ambulance transports (per a month per ten
thousand persons) by acute diseases [8] was used for
analysis.
2.3. Temperatures
Daily and monthly temperatures in Takamatsu area, Ja-
pan for the required periods were obtained from Taka-
matsu Local Meteorological Observatory, Japan Mete-
orological Agency [9]. Mean temperature in a month,
mea n tempe ratur e of maxi mum temperatures in a month,
mean temperature of minimum temperatures in a month,
maximum temperature in a month, minimum temperature
in a month and the number of days over the level of var-
ious temperatures in a month were used for analysis.
2.4. Statistical Analysis
Simple correlation analysis was used to test the signifi-
cance of the linear relationship among continuous vari-
ables: p < 0.05 was considered to be statistically signifi-
cant.
3. Results
Changes in mean temperature in a month are summarized
in Figure 1. There were not clear differences of mean
temperature in a month for 5 years. There were not also
clear differences of ambulance transports (per a month
per ten thousand persons) for 5 years (Figure 2).
We investigate the relationship between ambulance
transports and parameters of temperatures from July to
September for 5 years (2004-2008) in Takamatsu area,
Japan (Table 1). Ambulance transports were signifi-
cantly correlated with parameters of temperatures. Cor-
relation coefficient rate between ambulance transports
and mean temperature of maximum temperatures in a
month was highest among parameters (r = 0.738, p =
0.0017). The slope of the regression line (changes in
mean temperature of maximum temperatures in a month
vs changes in ambulance transports) was 0.597 (Figure
3). Accordingly, we found that a 1˚C in mean tempera-
ture of maximum temperatures in a month corresponded
to a 0.597 increase in ambulance transports (per a month
per ten thousand persons) in Takamatsu area.
In addition, the relation between ambulance transports
and the number of days of over the level of various tem-
Table 1. Simple correlation analysis between ambulance
transports and parameters of temperatures in Takamatsu
area, Japan.
r p
Mean temperature in a month 0.7280.0021
Mean tem perat ure of m axim um tem per at ures i n a m ont h 0.7380.0017
Mean tem perat ure of m inim um tem per at ures i n a m ont h 0.6680.0065
maximum temperature in a month 0.6930.0042
minimum temperature in a month 0.5550.0318
Figure 1. Changes in mean temperature (2004-2008).
Figure 2. Changes in ambulance transports (2004-2008)
(per a month per ten thousand persons).
Figure 3. Simple correlation analysis between ambulance
transports and mean temperature in a month.

Higher Temperatures Were Closely Associated with Higher Ambulance Transports in Takamatsu Area, Japan 74
peratures was also evaluated (Table 2). Ambulance
transports were significantly correlated with the number
of days of over the level of various temperatures, espe-
cially over the level of 32˚C (r = 0.782, p = 0.0006)
(Figure 4).
4. Discussion
We firstly investigated the link between ambulance tran-
sports and parameters of temperatures in Takamatsu area,
Japan. Ambulance transports were significantly associ-
ated with high temperatures.
In some literatures, the relation between high tem-
peratures and heat stroke in Japan [10-12]. Nakai et al.
investigated heat-related deaths in Japan from 1968 through
1994 and heat-related deaths were most prone to occur
on days with a peak daily temperature above 38 degrees
[10]. In addition, they reported that incidence of heat-
related deaths showed and exponential dependence on
the number of hot days [10]. Qui et al. reported that an
unusually hot spell in 1999 was followed by a high mor-
tality rate in Hokkaido , Japan [11]. Bai et al. also showed
that the number of un usual deaths in the summer of 1994
in Osaka, Japan was more compared to those of previous
years [12]. The human body dissipates heat in four ways:
convection, conduction, radiation and water evaporation.
When the temperature of the surrounding environment is
higher than the body temperature, water evaporation is
the only way in which the body can dissipate heat. When
the air temperature is over 34 degrees, cardiovascular and
nervous disorders can occur as a result of problems asso-
ciated with body temperature adjustment and metabolism
of water and salts [11]. Unexpectedly high temperatures
are particularly difficult for the elderly [13,14], and
chronic diseases [15]. In this study, we investigated the
relationship between ambulance transports and parame-
ters of temperatures, and close relationship was noted
between ambulance transports and high temperatures in
Takamatsu area, Japan. Although, we could not directly
evaluate the heat-related diseases or deaths, it seems
reasonable to suggest that simply dealing with high tem-
peratures in summer in Takamatsu city i.e. inno vation of
the thermal energy metabolism in cities and individual
coping with high temperatures might result in the ame-
lioration of ambulance transports in Takamatsu area,
Japan.
Potential limitation s still remain in this study. First, the
link between ambulance transports and temperatures,
which was noted in th is study, may not apply for the link
among individuals. Second, we could not directly evalu-
ate heat-related diseases or deaths. Third, daily data of
ambulance transports could not obtained in this study.
Therefore, we could not accurately evaluate the link be-
tween ambulance transports and high temperatures. Fur-
Table 2. Simple correlation analysis between ambulance
transports and number of days over the level of various
temperatures in a month.
r p
Number of days over 30˚C 0.682 0.0051
Number of days over 31˚C 0.778 0.0006
Number of days over 32˚C 0.782 0.0006
Number of days over 33˚C 0.723 0.0023
Number of days over 34˚C 0.677 0.0056
Number of days over 35˚C 0.644 0.0006
Figure 4. Simple correlation analysis between ambulance
transports and the number of days over the level of various
temperatures.
ther studies are required to prove such link.
REFERENCES
[1] “The Scientific Basis: Contribution of Working Group 1
to the Third Assessment Report,” Intergovernmental
Panel on Climate Change, Climate Change 2001, Cam-
bridge University Press, Cambridge, 2001, pp. 1-944.
[2] C. Aniello, K. Morgan, A. Busbey and L. Newland,
“Mapping Micro-Urban Heat Islands Using LANDSAT
TM and a GIS,” Computers & Geosciences, Vol. 21, No.
8, October 1995, pp. 965-969.
doi:10.1016/0098-3004(95)00033-5
[3] K. E. Smoyer, “A Comparative Analysis of Heat Waves
and Associated Mortality in St. Louis, Missouri - 1980
and 1995,” International Journal of Biometeorology, Vol.
42, No. 1, September 1998, pp. 44-50.
doi:10.1007/s004840050082
[4] W. B. Applegate, J. W. Jr. Runyan, L. Brasfield, M. L.
Williams, C. Konigsberg and C. Fouche, “Analysis of the
1980 Heat Wave in Memphis,” Journal of the American
Geriatrics Society, Vol. 29, No. 8, August 1981, pp. 337-

Higher Temperatures Were Closely Associated with Higher Ambulance Transports in Takamatsu Area, Japan 75
342.
[5] M. Lye and A. Kamal, “Effects of a Heatwave on Mortal-
ity-Rates in Elderly Inpatients,” Lancet, Vol. 1, No. 8010,
March 1977, pp. 529-531.
doi:10.1016/S0140-6736(77)91385-X
[6] “National Institute for Environmental Studies,” 2010.
Int er n e t A va il ab l e:http://www.nies.go.jp/health/HeatStro
ke/spot/index.html#at1 (in Japanese)
[7] “Fire Department Service in Takamatsu, Japan,” 2010.
Internet Available: http://www.city.takamatsu.kagawa.jp/
10991.html (in Japanese)
[8] “Fire and Disaster Management Agency,” 2010. Internet
Available: http://aeml.umin.ac.jp/hou/0690.html (in Jap-
anese).
[9] “Japan Meteorological Agency,” 2010. Internet Available:
http://www.data.jma.go.jp/obd/stats/etrn/index.php?prec_
no=72&prec_ch=%8D%81%90%EC%8C%A7&block_n
o=47891&block_ch=%8D%82%8F%BC&year=&month
=&day=&view= (in Japanese)
[10] S. Nakai, T. Itoh and T. Morimoto, “Deaths from
Heat-Stroke in Japan: 1968-1994,” International Journal
of Biometeorology, Vol. 43, No. 3, November 1999, pp.
124-127. doi:10.1007/s004840050127
[11] D. Qiu, T. Tanihata, H. Aoyama, T. Fujita, Y. Inaba and
M. Minowa, “Relationship between a High Mortality
Rate and Extreme Heat during the Summer of 1999 in
Hokkaido Prefecture, Japan,” Journal of Epidemiology,
Vol. 12, No. 3, May 2002, pp. 254-257.
[12] H. Bai, M. N. Islam, H. Kuroki, K. Honda and C. Waka-
sugi, “Deaths Due to Heat Waves during the Summer of
1994 in Osaka Prefecture, Japan, ” Nihon Hoigaku Zasshi,
Vol. 49, No. 4, August 1995, pp. 265-274. (in Japanese)
[13] J. B. Worfolk, “Heat Waves: Their Impact on the Health
of Elders,” Geriatric Nursing, Vol 21, No. 2, March -
April 2000, pp. 70-77. doi:10.1067/mgn.2000.107131
[14] T. S. Jones, A. P. Liang, E. M. Kibourrne, M. R. Griffin,
P. A. Patriarca, S. G. Wassilak, R. J. Mullan, R. F. Her-
rick, H. D. Jr. Donnell, K. Choi and S. B. Thancker,
“Morbidity and Mortality Associated with the July 1980
Heat Wave in St Louis and Kansas City, Mo,” Journal of
the American Medical Association, Vol 247, No. 24, June
1982, pp. 3327-3331.
doi:10.1001/jama.247.24.3327
[15] J. C. Semenza, C. H. Rubin, K. H. Falter, J. D. Selanikio,
W. D. Flanders, H. L. Howe and J. L. Wilhelm,
“Heat-Related Deaths during the July 1995 Heat Wave in
Chicago,” The New England Journal of Medicine, Vol.
335, No. 2, July 1996, pp. 84-90.
doi:10.1056/NEJM199607113350203