If you have nasal inflammation or runny nose from using CPAP, it may be that the air pressure is stronger than normal. It can cause irritation of the nasal mucosa. If the voltage is lowered and the Avg. AHI value is still less than 5, there is no problem. AHI < 5 is considered normal. In addition, I recommend going to see a doctor to consult and check the allergy symptoms as well.