Apparatus and method for monitoring breathing air

1. A method for monitoring breathing air of a person breathing via a face mask, the method comprising:

conducting a flow of fluid to be used as the breathing air through a fluid passage of a monitoring apparatus to a breathing hose of the face mask;

measuring a pressure of the breathing air inside the fluid passage of the monitoring apparatus;

measuring partial pressure of oxygen in the breathing air inside the fluid passage of the monitoring apparatus before the oxygen enters the breathing hose of the face mask;

estimating a partial pressure of oxygen in lungs of the person on the basis of the measured pressure of the breathing air and the measured partial pressure of oxygen in the breathing air;

comparing the estimated partial pressure of oxygen in the lungs with a pre-determined threshold partial pressure value and taking at least a partial pressure of water vapor of the lungs into account in the comparison; and

providing an indication of impending hypoxia, if the comparison indicates that the estimated partial pressure of oxygen in the lungs is at a level lower than the threshold value.

2. The method according to claim 1 , wherein the method further comprises at least one of the following:

providing the indication at least as a haptic indication;

providing the indication at least as a visual indication;

providing the indication at least as an audible indication.

3. The method according to claim 2 , wherein the method further comprises:

providing the haptic indication by a vibrating element of the face mask.

4. The method according to claim 1 , wherein the person is travelling in a cabin of an airplane, wherein the method further comprises:

measuring pressure of the cabin of the airplane; and

providing a warning to the person if the cabin is unpressurised.

5. The method according to claim 4 , wherein the method further comprises:

measuring altitude of the airplane; and

using the measured altitude to determine whether to provide another warning to the person.

6. The method according to claim 1 , wherein the method further comprises:

generating the breathing air by an onboard oxygen generation system.

7. The method according to claim 1 , wherein the method further comprises:

measuring a concentration of one or more other gaseous compounds in the breathing air;

comparing the concentration to another threshold; and

generating an indication that the concentration of the one or more other gaseous compounds is above the another threshold.

8. The method according to claim 1 , wherein the method further comprises:

examining whether the measured pressure of the breathing air inside the fluid passage changes; and

determining that there is leakage between the monitoring apparatus and the face mask if changes in the measured pressure of the breathing air are not detected.

9. The method according to claim 1 , wherein the method further comprises measuring a respiration frequency of the person.

10. An apparatus for monitoring breathing air of a person breathing via a face mask, the apparatus comprising:

a fluid passage configured to conduct a flow of fluid to be used as the breathing air through the apparatus;

a conduit coupling the fluid passage of the apparatus with the face mask, wherein the conduit is configured to conduct the flow of fluid from the fluid passage to the face mask;

a pressure sensor for measuring a pressure of the breathing air in the fluid passage;

a partial pressure sensor for measuring a partial pressure of oxygen in the breathing air in the fluid passage before the oxygen enters the face mask; and

a processor;

wherein the processor is configured to:

estimate a partial pressure of oxygen in lungs of the person on the basis of the measured pressure of the breathing air and the measured partial pressure of oxygen; and

compare the estimated partial pressure of oxygen in the lungs with a threshold and take at least a partial pressure of water vapor of the lungs into account in the comparison;

wherein the apparatus further comprises a signal generation element configured to provide an indication of impending hypoxia to the person when the comparison indicates that the estimated partial pressure of oxygen in the lungs is at a level lower than the threshold.

11. The apparatus according to claim 10 , wherein the apparatus is configured to:

provide the indication at least as a haptic indication;

provide the indication at least as a visual indication;

provide the indication at least as an audible indication.

12. The apparatus according to claim 10 , wherein the fluid passage is configured to receive fluid to be inhaled and to output the fluid to the conduit coupling the fluid passage with the face mask.

13. The apparatus according to claim 12 , wherein the apparatus further comprises a measurement chamber configured to accommodate the pressure sensor and the partial pressure sensor; and the measurement chamber has a flow connection with the fluid passage.

14. The apparatus according to claim 12 , wherein the apparatus is configured to:

examine whether the measured pressure of the breathing air inside the fluid passage changes; and

determine that there is leakage between the monitoring apparatus and the face mask if changes in the measured pressure of the breathing air are not detected.

15. The apparatus according to claim 12 , wherein the apparatus is configured to measure a respiration frequency of the person.

16. The apparatus according to claim 10 , wherein the apparatus further comprises at least one of:

a cabin pressure sensor;

a temperature sensor;

an altimeter;

a voltage measurement sensor to measure a voltage level of a battery of the apparatus;

a circuitry configured to measure concentration of one or more other gaseous compounds.