Impact of Environmental Conditions on the Pathogenesis of the Common Cold

Abstract

The common cold is a worldwide health issue, and is associated with severe complications in patients with chronic illnesses and disability, which can even be life‐threatening. More than 200 types of viruses are associated with the common cold. However, until now, there is still no effective protection against the cold. The fact that a cold cannot be prevented is reflective of a poor understanding of the etiology of the disease. The present study identified a relationship between the incidence of the common cold and environmental conditions, namely low temperature and air humidity. Three basic etiological factors of the common cold were identified: (1) Dry air, defined as relative humidity of <40%, challenges the lungs to maintain exhaled air humidity of approximately 100%. (2) Low temperature (<5°C) in combination with excessive relative humidity (>90%), challenges the lungs to maintain exhaled air temperature of approximately 37°C. (3) Common cold induced by lung chilling during sleep.ConclusionExtreme weather reduces airway defenses against viral infections. Therefore, adequate regulation of indoor air humidity (55%–70%) is expected to prevent most colds.