Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. I appreciate your health concern about your husband. Irritation or runny nose that seems to be caused by PAP therapy. Your nose is your airway’s humidifier. It warms and moistens the air that you breathe. If the PAP begins to dry your nose, your body will increase the production of mucus in the nose to add more moisture to the inhaled air. In some cases the dryness will cause irritation, burning and sneezing. These symptoms can be alleviated by the use of a humidifier with your PAP device. Some sleep specialists order a passover (cold water) humidifier with the initial PAP order. If you do not have one of these, speak with your sleep specialist. If you already have a humidifier and still experience these symptoms you may need a heated humidifier. This is a water pan that sits on a heating unit and is attached to PAP machine just like the passover humidifier. Heating the air and the water will allow the air to carry more moisture as it travels to your nose (just like the summer air is more humid than winter air). In almost all cases this resolves nasal congestion and irritation caused by PAP therapy. Hope I have answered your query. Let me know if I can assist you further.