A method of treating a patient having a lung condition that includes identifying a target haemoglobin-carbon monoxide level in the blood of the patient. The method also includes administering, to the patient, carbon monoxide at a first concentration for an initial time period, and measuring the haemoglobin-carbon monoxide level in the blood of the patient. The method also includes calculating, based on the measured haemoglobin-carbon monoxide level and the target haemoglobin-carbon monoxide level, a dose of carbon monoxide required to attain the target haemoglobin-carbon monoxide level within a determined time period. The method also includes administering, to the patient, the calculated dose of carbon monoxide for the determined time period to attain the target haemoglobin-carbon monoxide level in the blood of the patient.