Geographical distribution of the normal reference value of healthy adult male's total lung capacity
CAO Li-xia1，GE Miao1，HE Jin-wei1，WANG Zhi-kui2
1 Department of Geography,Shaanxi Normal University,Xian,710062 Shaanxi,China
2 College of Chemistry and Materials Science,Shaanxi Normal University,Xian,710062 Shaanxi,China
Correspondence to CAO Lixia,Department of Geography,Shaanxi Normal University,Xian,710062 Shaanxi,China E-mail: caolixia0712@126.com or caolixia 0712@stu.snnu.edu.cn.
Abstract：Objective The paper aims at supplying a basic for unifying the normal reference value standard of Chinese healthy adult males total lung capacity （TLC）.Methods We gathered 4,079 examples of the normal value of healthy adult men in 60 areas in China,and researched the relationship between the reference value of Chinese healthy adult males TLC and the eight geographical factors（Altitude;Annual Sunshine Duration;Percentage of Sunshine Duration;Annual Mean Air Temperature;Annual Range of Air Temperature;Annual Mean Relative Humidity;Annual Precipitation Amount;Annual Mean Wind Speed） by using the method of correlative analysis and regression analysis.Results It is founded that the correlation of geographical factors and the reference value of Chinese healthy adult males TLC are quite significant （F=13.348,P=0.000）.Applying the method of mathematical regression analysis,one regression equation is inferred:Y＾=5.928+0.0003826X1+0.001972X2-0.1192X3+0.1172X4-0.002356X7+0.5298X8±0.916.Conclusions If geographical values are obtained in some areas,the normal value of Chinese healthy adult males TLC of this area can be reckoned by using the regression equation.Furthermore,according to the similarity of the normal reference value of Chinese healthy adult males TLC,China can be divided into eight regions:Northeast China District,North China District,Northwest China District,Shanxi-Shaanxi-Inner Mongolia District,Middle and lower reaches Yangtze River district,Southeast China District,Southwest China District and Qinghai-Tibet Plateau District.
Key words：total lung capacity；normal reference value；geographical elements；regression analysis
INTRODUCTION
The humans survival needs the oxygen,if there is no foods in human body,the human will pass through several weeks,and if no water,he also may pass through several days,but the human only live several minutes without the oxygen in body,which has not the ability of laying in the oxygen,so it is the live manner for human to provide the oxygen by outside environment.The lung helps to achieve the function that exchanges the gas between human body and outside environment.The pulmonary function examination is one of the main bases of work ability appraisal to pneumoconiosis patients,also is the main examination method to evaluate the pulmonary function harm of dust worker,the total lung capacity （TLC） assessing is one of the important indexes of pulmonary function examination,moreover TLC assessing has anatomy significance,it has the close relation with the breath physiology and the pathophysiology.Therefore,the normal reference value of TLC is the important basis in clinical diagnosis and the illness sickness prevention,is an important reference norm in the clinical test,and has extremely vital significance to judge organism whether have pathological change.At present,domestic and foreign lacks of the unified standards of the normal reference value of TLC seriously influences clinical diagnosis accuracy.This article researched the relationship between the reference value of Chinese healthy adult males TLC and the geographical factors with the stepwise regression analysis and discovered certain regularity.
MATERIALS AND METHODS
Normal Reference Value of Total Lung Capacity
We have searched some materials in some databases and some Science and Technology database,and bought some materials in library in Harbin,Changchun Taiyuan,Xian,Fuzhou,Nanjing,Xining,Lanzhou,Yinchuan.
We gathered 4,079 examples of the normal value of healthy adult men in 60 areas in China,the age of healthy adult males range from 18 to 79 and these examples have been collected in China.
Geographical Factors
The geographical factors come from relevant geographical works and dictionaries［22~24］.The selected geographical factors include altitude （X1）,annual sunshine duration （X2）,annual percentage of sunshine duration （X3）,annual mean air temperature （X4）,annual range of air temperature （X5）,annual mean relative humidity （X6）,annual precipitation amount （X7）,and annual mean wind speed （X8）.
Altitude （X1）:The mean sea level which is determined by long time observation of sea level is called mean sea level.If one point is higher than mean sea level,its height is called altitude;the measured unit is in meters （m）.
Annual sunshine duration （X2）:The duration that the centre of sun rises from eastern horizon and falls into west,is called the possible sunshine hours.For sun is shaded by fog and cloud or affected by obstacle,the actual sunshine time is called the observed sunshine hours.The amount of the observed sunshine hours in one year is called annual sunshine duration;the measured unit is in hours （h）.
Annual percentage of sunshine duration （X3）:The percentage of observed sunshine duration which takes up in the possible sunshine duration for a given year;the measured unit is in percentage （%）.
Annual mean air temperature （X4）:Air temperature is defined as the temperature in screen at 1.5 m above the ground surface.The average of routinely observed values for a given year is called annual mean air temperature;the measured unit is in centigrade （℃）.
Annual range of air temperature （X5）:The difference between mean temperature of the warmest month and the coldest month in one year;the measured unit is in centigrade （℃）.
Annual mean relative humidity （X6）:The ratio of actual vapour pressure in air to saturation vapour pressure at current temperature is called relative humidity.The average of routinely observed values for a given year is called annual mean relative humidity;the measured unit is in percentage （%）.
Annual precipitation amount （X7）:Precipitation amount is defined as the accumulated depth in a horizontal container that collected the liquid or solid precipitation （after melting） fallen from the sky.The amount by taking an addition of daily total precipitation for a given year is called annual precipitation amount;the measured unit is in millimeters （mm）.
Annual mean wind speed （X8）:Wind speed is defined as the horizontal distance that the air moves in unit time.The averages of routinely observed values for a given year is called annul mean wind speed;the measured unit is in meters per second （m/s）.
Correlation Analysis and Regression Analysis
Correlation analysis
By using the method of mathematical correlation analysis［25~26］,single correlation coefficients between the reference value of Chinese healthy adult males TLC and the eight geographical factors ［altitude （X1）,annual sunshine duration （X2）,annual percentage of sunshine duration （X3）,annual mean air temperature （X4）,annual range of air temperature （X5）,annual mean relative humidity （X6）,annual precipitation amount （X7）,annual mean wind speed （X8）］ can be calculated respectively:r1=0.463 （P1=0.000）,r2=0.261（P2=0.022）,r3=-0.527（P3=0.000）,r4=-0.409（P4=0.000）,r5=-0.526（P5=0.000）,r6=-0.004（P6=0.997）,r7=0.154（P7=0.181）,r8=0.237（P8=0.038）.
If P value is lower than 0.01,it means the correlation is quite significant.If it occurs between 0.05 and 0.01,the correlation is just significant.If P value is higher than 0.05,it means the correlation is not significant.
Regression equation
According to the normal reference value of Chinese healthy adult males TLC and geographical factors,one regression equation is inferred by using the method of stepwise regression analysis:
Y＾=5.928+0.0003826X1+0.001972X2-0.1192X3+0.1172X4-0.002356X7+0.5298X8 ±0.916
In the above equation,Y＾ is the normal reference value of TLC of Chinese healthy adult males （L）;X1 is the altitude （m）;X2 is the annual sunshine duration （h）;X3 is the annual percentage of sunshine duration （%）;X4 is the annual mean air temperature （℃）;X7 is the annual precipitation amount （mm）;X8 is the annual mean wind speed （m/s）;0.916 is the value of the residual standard deviations［3］.
By using the F-test,F equals 13.348,P value equals 0.000.Because P value is lower than 0.01,which means the correlation is quite significant.
DISCUSSION
Geographical environment is the physical basis on which human beings depend on.It is an organic whole that consists of the geographical factors,such as:air,water,soil,living things and minerals.Human organism is in a contradictory process of unity with the geographical environment.On one hand,the living organism absorbs nutritious substances from the geographical environment;on the other hand,it excretes waste materials into the geographical environment.The process of metabolism,along with the exchange of energy,forms the dynamic balance of physical exchange between human beings and geographical environment.Therefore,normal reference values of TLC are the same in the same geographical environments,and normal reference values of TLC are different in different geographical environments.There is a dependent relationship between the normal reference value of TLC and geographical factors.
From single correlation coefficients,it is found that the normal value of Chinese healthy adult males TLC increases with the increase of the altitude （X1）,the correlation is just significant.With the increase of the annual sunshine duration （X2）,the normal value of Chinese healthy adult males TLC increases,the correlation is significant.With the increase of the annual percentage of sunshine duration （X3）,the normal value of Chinese healthy adult males TLC decreases,the correlation is just significant.With the increase of the annual mean air temperature （X4）,the normal value of Chinese healthy adult males TLC decreases,the correlation is just significant.With the increase of the annual range of air temperature （X5）,the normal value of Chinese healthy adult males TLC decreases,the correlation is just significant.With the increase of the annual mean relative humidity （X6）,the normal value of Chinese healthy adult males TLC decreases,the correlation is not significant.With the increase of the annual precipitation amount （X7）,the normal value of Chinese healthy adult males TLC increases,the correlation is significant.With the increase of the annual mean wind speed （X8）,the normal value of Chinese healthy adult males TLC increases,the correlation is significant.
DIVISION
The Peoples Republic of China is situated in the eastern part of Asia and on the west coast of the Pacific Ocean.It has a vast territory of 9.6 million square kilometers.The distance from east to west is over 5,000 kilometers and from north to south over 5,500 kilometers.Chinese topography varies from cloud-capped peaks to basins of different shapes and sizes,from wide,rolling plateaus to low,broad plains.There are great deserts and wilds in the northwest,while rivers,streams and lakes are on the plains of the middle and lower reaches of the Changjiang River.
The topographical outline of China is a three-step West-East staircase.It is high in the western area and low in the eastern area.It begins from the Qinghai-Tibet plateau,which is mostly 4，000 meters above sea level.Crossing the Kunlun and Qilian ranges on the plateaus northern edge and the Hengduan Mountains on its eastern edge,the land slopes away to highlands and basins mostly from 1，000 to 2，000 meters above sea level;then it descends further eastward to hilly regions and plains mostly below 500 meters.
According to the dependent relations between the normal value of Chinese healthy adult males TLC and geographical factors,furthermore,by basing itself on the geographical factors,China can be divided into eight Districts:Northeast China District,North China District,Southwest China District,Shanxi-Shaanxi-Inner Mongolia District,Middle and lower reaches of the Changjiang River District,Southeast China District,Northwest China District,Qinghai-Tibet Plateau District （Figure 1）.
Figure 1 A divisional map of China
Northeast China District
It includes Liaoning Province,Jilin Province and Heilongjiang Province.For example,in the Shenyang area,the altitude （X1） is 44.7 m,the annual sunshine duration （X2） is 2，573.0 h,the annual percentage of sunshine duration （X3） is 58.0 %,the annual mean air temperature （X4） is 8.5 ℃,the annual precipitation amount （X7） is 734.5 mm,and the annual mean wind speed （X8） is 3.5 m /s.By using the regression equation,the calculated normal value of Chinese healthy adult males TLC can be obtained as follow:5.661±0.916 （L）.
North China District
It includes Beijing City,Tianjin City,Hebei Province,Shandong Province and Henan Province.For example,in the Beijing area,the altitude （X1） is 31.3 m,the annual sunshine duration （X2） is 2，763.7 h,the annual percentage of sunshine duration （X3） is 62.0 %,the annual mean air temperature （X4） is 12.3℃,the annual precipitation amount （X7） is 571.9 mm,and the annual mean wind speed （X8） is 2.5 m /s.By using the regression equation,the calculated normal value of Chinese healthy adult males TLC can be obtained as follow:5.577±0.916 （L）.
Northwest China District
It includes Gansu Province,the Ningxia Hui Autonomous Region and the Xinjiang Uygur Autonomous Region.For example,in the lanzhou area,the altitude （X1） is 1，517.2 m,the annual sunshine duration （X2） is 2，607.6 h,the annual percentage of sunshine duration （X3） is 55.0 %,the annual mean air temperature （X4） is 9.8 ℃,the annual precipitation amount （X7） is 327.7 mm,the annual mean wind speed （X8） is 0.9 m/s.By using the regression equation,the calculated normal value of Chinese healthy adult males TLC can be obtained as follow:5.948±0.916 （L）.
Shanxi-Shaanxi-Inner Mongolia District
It includes Shanxi Province,Shaanxi Province and the Inner Mongolia Autonomous Region.For example,in the Taiyuan area,the altitude （X1） is 778.3 m,the annual sunshine duration （X2） is 2，756.0 h,the annual percentage of sunshine duration （X3） is 58.5 %,the annual mean air temperature （X4） is 10.0 ℃,the annual precipitation amount （X7） is 432.1mm,and the annual mean wind speed （X8） is 2.2 m /s.By using the regression equation,the calculated normal value of Chinese healthy adult males TLC can be obtained as follow:6.070±0.916 （L）.
Middle and lower reaches of the Changjiang River District
It includes Hubei Province,Hunan Province,Anhui Province,Jiangxi Province,Zhejiang Province,Jiangsu Province and Shanghai city.For example,in the Shanghai area,the altitude （X1） is 5.5 m,the annual sunshine duration （X2） is 1，986.1 h,the annual percentage of sunshine duration （X3） is 48.0 %,the annual mean air temperature （X4） is 16.6℃,the annual precipitation amount （X7） is 1，123.7 mm,and the annual mean wind speed （X8） is 3.8 m /s.By using the regression equation,the calculated normal value of Chinese healthy adult males TLC can be obtained as follow:5.436±0.916 （L）.
Southeast China District
It includes Fujian Province,Guangdong Province,Hainan Province,Taiwan Province,Hongkong Special Administrative Region and Macao Special Administrative Region.For example,in the guangzhou area,the altitude （X1） is 41.0 m,the annual sunshine duration （X2） is 1，906.0 h,the annual percentage of sunshine duration （X3） is 39.0 %,the annual mean air temperature （X4） is 22.0 ℃,the annual precipitation amount （X7） is 1，736.1 mm,the annual mean wind speed （X8） is 1.9 m/s.By using the regression equation,the calculated normal value of Chinese healthy adult males TLC can be obtained as follow:4.495±0.916 （L）.
Southwest China District
It includes Chongqing City,Sichuan Province,Yunnan Province,Guizhou Province,and the Guangxi Zhuang Autonomous Region.For example,in the Chengdu area,the altitude （X1） is 506.1 m,the annual sunshine duration （X2） is 1，239.0 h,the annual percentage of sunshine duration （X3） is 25.0 %,the annual mean air temperature （X4） is 16.2 ℃,the annual precipitation amount （X7） is 997.6mm,and the annual mean wind speed （X8） is 1.2 m /s.By using the regression equation,the calculated normal value of Chinese healthy adult males TLC can be obtained as follow:5.981±0.916 （L）.
Qinghai-Tibet Plateau District
It includes the Qinghai Province and Tibet Autonomous Region.For example,in the Lhasa area,the altitude （X1） is 3，648.9 m,the annual sunshine duration （X2） is 3，021.7 h,the annual percentage of sunshine duration （X3） is 65.0 %,the annual mean air temperature （X4） is 8.0℃,the annual precipitation amount （X7） is 462.4 mm,and the annual mean wind speed （X8） is 2.2 m /s.By using the regression equation,the calculated normal value of Chinese healthy adult males, TLC can be obtained as follow:6.443±0.916 （L）.
FUNDING
Project 40671005 is supported by National Natural Science Foundation of China.
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