空氣溫度       干空氣密度       飽和空氣密度 

℃                   kg/m3                kg/m3 

-20                 1.396                  1.395 

-19                 1.394                  1.393 

-18                 1.385                  1.384 

-17                 1.379                  1.378 

-16                 1.374                  1.373  

-15                 1.368                  1.367 

-14                 1.363                  1.362 

-13                 1.358                  1.357 

-12                 1.353                  1.352 

-11                 1.348                  1.347 

-10                 1.342                  1.341 

-9                   1.337                  1.336 

-8                   1.332                  1.331  

-7                   1.327                  1.325 

-6                   1.322                  1.32 

-5                   1.317                  1.315 

-4                   1.312                  1.31 

-3                   1.308                  1.306 

-2                   1.303                  1.301 

-1                   1.298                  1.295 

0                    1.293                  1.29 

1                    1.288                  1.285 

2                    1.284                  1.281 

3                    1.279                  1.275 

4                    1.275                  1.271 

5                    1.27                    1.266 

6                    1.265                  1.261 

7                    1.261                  1.256 

8                    1.256                  1.251 

9                    1.252                  1.247 

10                  1.248                  1.242 

11                  1.243                  1.237 

12                  1.239                  1.232 

13                  1.235                  1.228 

14                  1.23                    1.223 

15                  1.226                  1.218 

16                  1.222                  1.214 

17                  1.217                  1.208 

18                  1.213                  1.204 

19                  1.209                  1.2 

20                  1.205                  1.195 

21                  1.201                  1.19 

22                  1.197                  1.185 

23                  1.193                  1.181 

24                  1.189                  1.176 

25                  1.185                  1.171 

26                  1.181                  1.166 

27                  1.177                  1.161 

28                  1.173                  1.156 

29                   1.169                 1.151 

30                   1.165                 1.146  

31                   1.161                 1.141 

32                   1.157                 1.136 

33                   1.154                 1.131 

34                   1.15                   1.126 

35                   1.146                 1.121 

36                   1.142                 1.116 

37                   1.139                 1.111 

38                   1.135                 1.107 

39                   1.132                 1.102 

40                   1.128                 1.097 

41                   1.124                 1.091 

42                   1.121                 1.086 

43                   1.117                 1.081 

44                   1.114                 1.076 

45                   1.11                   1.07 

46                   1.107                 1.065 

47                   1.103                 1.059 

48                   1.1                     1.054 

49                   1.096                  1.048 

50-54              1.093                  1.043 

55-59              1.076                  1.013 

60-64              1.06                    0.981 

65-69              1.044                  0.946 

70-74              1.029                  0.909 

75-79              1.014                  0.868 

80-84              1                        0.823 

85-89              0.986                  0.773 

90-94              0.973                  0.718 

95-99              0.959                  0.656 

100                 0.947                  0.589 

單位體積空氣所具有的質量稱為空氣的密度，用ρ來表示。即：

                                    （2-1）

式中  ρ——空氣的密度，kg/m3；

     M——空氣的質量，m；

     V——空氣的體積，m3。

一般來說，空氣的密度是隨溫度、濕度和壓力的變化而變化的。在標準大氣狀況下（P＝101325Pa，t＝O℃，＝O%），干空氣的密度為1.293 kg/m3。濕空氣密度的計算公式為：

               ρ濕＝0.003484（1－0.378）           (2-2)

式中  P——空氣的壓力，Pa；

      T——熱力學溫度（T＝273+t），K；

      t ——空氣的溫度，℃；

     ——相對濕度，%；

     P飽——溫度為t（℃）時的飽和水蒸氣壓力(見表1-9)，pa。

由上式可見，壓力越大，溫度越低，空氣密度越大。當壓力和溫度一定時，濕空氣的密度總是小于干空氣的密度。

在礦井通風中，由于通風系統內的空氣溫度、濕度、壓力各有不同，空氣的密度也有所變化，但變化范圍有限。在研究空氣流動規律時，要根據具體情況考慮是否忽略這種變化。

    一般將空氣壓力為101325Pa，溫度為20℃，相對濕度為60%的礦井空氣稱為標準礦井空氣，其密度為1.2kg/m3。