Nasal congestion is a common symptom across various nasal conditions. Many nasal diseases can lead to congestion. For instance, a less common cause could be a nasal bone fracture. If a nasal bone fracture is accompanied by a deviated septum, it can result in nasal congestion. Another cause is allergic rhinitis, which may lead to swollen turbinates, thereby causing congestion. Additionally, sinusitis can cause nasal congestion due to blockage by purulent secretions. However, nasal congestion from different diseases has its unique characteristics.

Let's discuss two specific cases. One common condition is a deviated septum. It's important to distinguish between two concepts: a deviated septum doesn’t necessarily have to be straight. This is especially common during childhood development, where various factors like adenoid hypertrophy, frequent rhinitis, and sinusitis can influence it. Regardless of the cause of nasal obstruction, children might resort to mouth breathing as they grow. The increased mouth breathing leads to increased airflow through the mouth. Consequently, the top of the mouth (commonly known as the hard palate or upper dental arch) elevates to accommodate the increased airflow. As the upper dental arch rises, the volume of the mouth increases, naturally reducing the upper surface area of the nasal cavity. Although the cranial base above the nasal cavity remains unchanged, the elevation of the upper dental arch reduces the upper surface area of the nasal cavity. This is the most common cause of a deviated septum.

We have made some unintentional observations, such as the nasal ventilation status being a crucial physical examination for selecting pilots and other specialized roles. These special professions, which must quickly adapt to changes in external environmental pressure, require excellent nasal ventilation. Good nasal ventilation ensures that the tube regulating pressure inside the ear can ventilate quickly. If the nasal passage is blocked, this tube cannot ventilate quickly, leading to fluid buildup in the ear, which can cause hearing loss and secretory otitis media. For example, some people have minor nasal issues, and as soon as the plane lands, they can't hear anything, indicating a problem with the regulatory function. If the regulatory function fails, it can also lead to sinus problems. Therefore, certain specialized jobs require excellent nasal regulation ability, and when selecting pilots, it's essential to carefully examine whether the person has a deviated septum.

I recall a medical examination where almost 90% of the participants failed, mostly due to a deviated septum. This figure might even be higher when it comes to pilot candidates. What does this indicate? It shows that a deviated septum is very common. But is it a disease? No. It might prevent someone from working in specialized professions, but they can still work in ordinary jobs, like being a doctor or other professions.

Nasal obstruction caused by an unregulated deviated septum is considered a disease. It leads to persistent nasal obstruction on one or both sides due to turbinate hypertrophy on the deviated side or the opposite side. Only in such cases do we diagnose a deviated septum as a condition, which is a very common cause of nasal obstruction. It's essential to clarify the issue of nasal obstruction because many people worry about whether surgery is necessary. Surgery is only considered when symptoms cannot be alleviated through other means and must be approached cautiously.

Another cause of nasal obstruction is nasal tumors. Many nasal tumors present with nasal obstruction as the primary symptom, particularly in the nasal cavity and nasopharynx, where the obstruction is persistent. Tumors gradually enlarge, worsening the obstruction. Certain tumors, such as nasopharyngeal angiofibroma common in young people, are accompanied by severe nasal bleeding. Nasal obstruction caused by nasopharyngeal carcinoma, sinus tumors, or nasal papillomas can result in blood in nasal mucus, which is an early symptom of nasal tumors. Persistent, worsening nasal congestion with blood in nasal discharge requires immediate medical attention.

Another cause of nasal obstruction is adenoid hypertrophy, which mainly affects children. Adenoids change with age, and the nasal congestion they cause is particularly noticeable during sleep. When sleeping, muscles relax, especially the soft palate and tongue base, which can cause the already enlarged adenoids to block the posterior nostrils. This obstruction first manifests as snoring and heavy breathing at night. In severe cases, children may also breathe through their mouths during the day, similar to choanal atresia. Some children may experience breathing difficulties while drinking milk or eating at around one year of age because they need to close their mouths to eat, but cannot breathe through their mouths, and their nasal ventilation is poor. As a result, they need to pause frequently while drinking milk to catch their breath.

Children can also experience nasal congestion due to choanal atresia, a congenital developmental abnormality. Different characteristics of nasal congestion suggest different diseases. Some can be self-regulated, such as allergic rhinitis, which can be managed by avoiding allergens; however, persistent nasal congestion requires hospital treatment.