The air in the alveoli is at body temperature and saturated with water. Air in the environment is usually at a different temperature and has a lower water saturation. Thus as a person breaths there is a loss of water from the body which is termed the humidity deficit.
water content in mg/L at °C outside the body =
= (relative humidity in percent) * (absolute humidity at °C when saturated) / 100%
water content in mg/L at °C in the alveoli =
= (absolute humidity at °C when saturated)
humidity deficit in mg/L =
= (water content in mg/L in alveoli) - (water content in mg/L in environment)
water loss in mg per minute of quiet breathing =
= (tidal volume in liters per breath) * (breaths per minute) * (humidity deficit in mg/L)
water loss in mL per day =
= (water loss in mg per minute) * 1440 / 1000
The higher the humidity of the inspired air, the lower the humidity deficit.
|
Temperature in °C |
Absolute Humidity in mg/L Air When Saturated |
|
19 |
16.3 |
|
20 |
17.3 |
|
21 |
18.4 |
|
22 |
19.4 |
|
23 |
20.6 |
|
24 |
21.8 |
|
25 |
23.0 |
|
26 |
24.4 |
|
27 |
25.8 |
|
28 |
27.2 |
|
29 |
28.8 |
|
30 |
30.4 |
|
31 |
32.0 |
|
32 |
33.8 |
|
33 |
35.6 |
|
34 |
37.6 |
|
35 |
39.6 |
|
36 |
41.7 |
|
37 |
43.9 |
|
38 |
46.2 |
|
39 |
48.6 |
|
40 |
51.1 |
|
41 |
53.7 |
If the data in the first 2 columns is analyzed with JMP:
absolute humidity of air when saturated at a given temperature =
= (0.03838 * ((temperature in °C)^2)) - (0.62339 * (temperature in °C)) + 14.521
Specialty: Pulmonology
ICD-10: ,
