Aside from its role in your sense of smell, the nose has three important functions as part of your respiratory system. It warms, humidifies and filters the air you breathe, but it can't do any of these things unless the nasal passages are clear. Everyone has had an occasional stuffy nose from a cold, but chronic blockage can be a serious problem. Blockage could be caused by swelling in the membranes of the nasal passages, a condition called rhinitis (RYE-NIGHT-IS). There could be any number of reasons for this, including allergies, sensitivity to smoke or other pollutants, or infection. Overuse of commercial nasal sprays can often make these conditions worse. Persistent inflammation can lead to the development of polyps, which further obstruct the nasal passages and require surgery for removal. An injury, perhaps from many years ago, can be another possible cause for nasal blockage. Only a thorough examination by an otolaryngologist (OH-TOE-LAIR-IN-JOLLA-GIST) can determine why your nasal passages aren't letting through all the air they should. Once the cause of the problem is determined, you can discuss the best method of treatment and start to breathe easier.