Rhinocrisy

For years I’ve been hearing the bullshit hypothesis that there are more colds in winter because people tend to spend more time indoors in the winter and thus are more likely to transmit infections. This makes very little sense, especially in cities. I’ve also been hearing there is “no evidence that exposure to cold weather makes you more likely to get a cold”. This is more likely a failure of the crappy case-control studies performed to measure the effect. I’m much happier with the “cold weather causes immunosuppression” hypothesis, which I’m gratified to read is favored by some “rhinologists”^*. From Eccles, R., “An explanation for the seasonality of acute upper respiratory tract viral infections.” Acta oto-laryngologica, Mar. 2002:

Despite a great increase in our understanding of the molecular biology of the viruses associated with acute upper respiratory tract viral infections (URTIs) there is a remarkable lack of knowledge and ideas about why URTI should exhibit a seasonal incidence. Most publications in this area either acknowledge a complete lack of any explanation for the seasonality of URTI or put forward an explanation relating to an increased “crowding” of susceptible persons in winter. This review will discuss some of the ideas concerning the seasonality of URTI and put forward a new hypothesis for discussion, namely that seasonal exposure to cold air causes an increase in the incidence of URTI due to cooling of the nasal airway. The hypothesis is supported by literature reports demonstrating that inhalation of cold air causes cooling of the nasal epithelium, and that this reduction in nasal temperature is sufficient to inhibit respiratory defences against infection such as mucociliary clearance and the phagocytic activity of leukocytes. A case is also made to suggest that warming of the nasal airway during fever and nasal congestion may help to resolve a current URTI.

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^* Unfortunately, they do not actually study rhinos, and the journal “Rhinology” is not full of papers on rhino anatomy and dietary habits.