The . The cold air can do a few things that can result in you becoming "sick". The cold air can lower your immune system thus making you more susceptible to viruses that cause the common cold or flu. Also there is the idea that viruses spread faster in cold air, making it easier to catch when you are in the cold so to speak. On the other hand, the fact that you have COPD means that your lungs are already in a more fragile state than a person with healthy lungs, and the cold air can act as a trigger to bring about a COPD exacerbation( worsening of your COPD symptoms). I will also take this opportunity to remind you to get your annual flu vaccine; the flu is notorious for causing COPD exacerbation as well as pneumonia. Take good care, .