Why generalized body ache strikes first during every change of seasons

Just as Korean medicine viewed the lung as our body's canopy of the lungs and the frontline against the outside world, modern medicine places strong emphasis on the lung's immunological importance. Beyond facilitating oxygen exchange, the lung functions as a vast immune organ directly exposed to the external environment across our body's largest surface area, spanning roughly 70 to 100 square meters. With every breath, microorganisms, viruses, bacteria, and airborne pollutants attempt to reach the pulmonary alveolus. To block these intruders, the lung maintains a sophisticated immune system. First, the cilia of the nasal and bronchial mucosa move continuously like fine brooms to sweep foreign particles outward. The mucus layer traps harmful substances with its viscous surface. Deeper within, sentinel cells known as alveolar macrophages stand ready to engulf and neutralize invaders. Specialized immune cells such as lymphocytes and dendritic cells are also distributed throughout lung tissue to regulate and retain memory of immune responses, securing long-term defense. Catching colds easily during seasonal transitions occurs because sharp temperature drops and dry environments weaken this defense system. Cold, dry air damages the bronchial mucosa and impairs the motility of cilia, allowing viruses and bacteria to enter more freely. Furthermore, when stress or sleep deprivation triggers excessive secretion of cortisol, immune cell activity diminishes and inflammatory responses occur more readily. These combined factors lower lung immunity, ultimately triggering the onset of a cold. Recent studies also examine how inflammation in the lung can contribute to systemic chronic inflammation, as well as how the lung interacts with intestinal health through the gut-lung axis. This indicates that lung health extends beyond local respiratory symptoms to influence systemic immune balance. Caring for the lung is therefore essential not only for preventing common colds, but also for supporting whole-body immunity.