A Lung condition monitoring device comprising a mouthpiece for forcibly exhaling air there through; a humidity sensor unit having a nanoparticle based humidity sensor with variable electrical resistance based on a level of adsorption of water molecule thereon due to humidity of the exhaled air; a real time monitoring unit for monitoring a lung condition, operatively connected to said humidity sensor having correlating means for correlating the change in a humidity level and the related variation in the electrical resistance due to exhalation to a peak flow rate of the exhaled air, wherein said real time monitoring unit is configured to detect a maximum change in the electrical resistance across the humidity sensor and correlating the same with the peak flow rate of exhalations from the lungs; the lung condition monitoring device characterised in that: the humidity sensor includes one or more films of porous CdS nanoparticles, each comprising Au nanoparticle embedded thermally conductive paper substrate (301T1) having thereon the porous CdS nanoparticles constituting a nanoparticle surface for rapid adsorption of the water molecules, and silver electrodes (301T2) for operatively connecting said nano particle surface with the real time monitoring unit; said real time monitoring unit includes a plurality of indicator LEDs on a housing of the real time monitoring unit for indicating status of the lungs and an indicator LED control module configured to activate one or more of the indicator LEDs depending on the change in the electrical resistance of the humidity sensor and correlating the same with the peak flow rate of exhalations from lungs; and a heating arrangement comprising a heating element cooperative with said humidity sensor to increase temperature of the humidity sensor post adsorption of the water molecules for rapid desorption of the water molecule from the humidity sensor and recovery of the humidity sensor for subsequent detection of the humidity level. a mouthpiece for forcibly exhaling air there through; a humidity sensor unit having a nanoparticle based humidity sensor with variable electrical resistance based on a level of adsorption of water molecule thereon due to humidity of the exhaled air; a real time monitoring unit for monitoring a lung condition, operatively connected to said humidity sensor having correlating means for correlating the change in a humidity level and the related variation in the electrical resistance due to exhalation to a peak flow rate of the exhaled air, wherein said real time monitoring unit is configured to detect a maximum change in the electrical resistance across the humidity sensor and correlating the same with the peak flow rate of exhalations from the lungs; the lung condition monitoring device characterised in that: the humidity sensor includes one or more films of porous CdS nanoparticles, each comprising Au nanoparticle embedded thermally conductive paper substrate (301T1) having thereon the porous CdS nanoparticles constituting a nanoparticle surface for rapid adsorption of the water molecules, and silver electrodes (301T2) for operatively connecting said nano particle surface with the real time monitoring unit; said real time monitoring unit includes a plurality of indicator LEDs on a housing of the real time monitoring unit for indicating status of the lungs and an indicator LED control module configured to activate one or more of the indicator LEDs depending on the change in the electrical resistance of the humidity sensor and correlating the same with the peak flow rate of exhalations from lungs; and a heating arrangement comprising a heating element cooperative with said humidity sensor to increase temperature of the humidity sensor post adsorption of the water molecules for rapid desorption of the water molecule from the humidity sensor and recovery of the humidity sensor for subsequent detection of the humidity level. the humidity sensor includes one or more films of porous CdS nanoparticles, each comprising Au nanoparticle embedded thermally conductive paper substrate (301T1) having thereon the porous CdS nanoparticles constituting a nanoparticle surface for rapid adsorption of the water molecules, and silver electrodes (301T2) for operatively connecting said nano particle surface with the real time monitoring unit; said real time monitoring unit includes a plurality of indicator LEDs on a housing of the real time monitoring unit for indicating status of the lungs and an indicator LED control module configured to activate one or more of the indicator LEDs depending on the change in the electrical resistance of the humidity sensor and correlating the same with the peak flow rate of exhalations from lungs; and a heating arrangement comprising a heating element cooperative with said humidity sensor to increase temperature of the humidity sensor post adsorption of the water molecules for rapid desorption of the water molecule from the humidity sensor and recovery of the humidity sensor for subsequent detection of the humidity level.