Spring marathons and cold air issues

For the second year running (excuse the pun!), I have been coughing following running. Last year was obviously worse, with having something like pneumonia, but there is clearly now some kind of issue with running in the cold which I don't remember from before. Anyhow, until temperatures climb back to something in the teens, I shan't be doing any intensive running. Curiously, just as I was considering this I met an older marathoner who only runs autumn marathons for this exact reason. But I am running this spring marathon, so.... I am going to sink to running a couple of times a week in a fitness centre on a machine! Not sure how I feel about this... Longand steady runs will continue outdoors but without the power surges.