It all basically comes down to a person’s immune system. If you’re happy, healthy, and have a strong immune system, you won’t get sick when sitting in a draft. If for some reason your immune system is down a little, you will, i.e. if the body is weak in relation to the climatic factor
According to TCM, Defensive Qi flows in the area between skin and muscles. This flow of energy acts as a barrier to the outside world, preventing invasion of pathogenic factors. We believe that wind is the vehicle which carries pathogens into the body so sitting in a draft is sitting in Big Wind.
Years ago, I visited a friend whose baby had just died. We were sitting outside, in a draft, and I remember wondering about the potential of illness. Because it was such a sad time, our energy was very low and the next morning I work up with a screaming cold.
When we eat, our body takes energy from the food and sends it to the Lungs. The Lungs then turn some of this energy into Defensive Qi and sends it to the area between the skin and muscles, so the quality of the food we eat is important to our immune system.
Besides protecting the body, Defensive Qi has other functions: it keeps the skin moist and warm, it partially nourishes the muscles and it controls sweating, thereby regulating body temperature.
If Defensive Qi is weak, it will fail to hold fluids in the body leading to day-time sweating. Conversely, if one has a cold, herbs are given which induce sweating and the expulsion of the pathogenic Wind-Cold factor.
As I mentioned, Wind is the vehicle through which pathogenic factors invade the body. Wind-Cold creates cold symptoms like a runny nose and eyes. Wind-Heat creates heat symptoms like fever and dryness. Wind-Cold can turn into Heat if not treated in time. Wind-Damp creates a feeling of heaviness and aching muscles.
Often the invading pathogenic factor creates blockage in the area where Defensive Qi flows resulting in stagnation in the joints. The type of pain is explained pertaining to climatic factors too, i.e. Wind will lead to pain moving from joint to joint and will mostly be in the upper part of the body. Cold leads to intense pain in one joint. Dampness will result in swollen joints, usually in the lower part of the body.
Invading pathogenic factors create many more situations, this article is intended as an example of how TCM looks at conditions so differently to the view of Western Medicine.