Why is it difficult for asthma patients in winter?

As soon as winter comes, it is very difficult for senior citizens, especially those with asthma. The environment inside the house is also one of the most difficult from November to February for those who are physically weak and have been taking asthma medicine for a long time.
According to the doctor, because the windows and doors of the house are closed to avoid the cold, the carbon dioxide that we throw does not get out sufficiently and the oxygen is also reduced, so it is generally difficult for people with asthma. If it's winter, you should not sit in such a way that the air does not come in from anywhere. If it is winter or cold, you should not close all the windows and doors of the house so that oxygen does not enter from outside. By doing this, the amount of oxygen decreases and the amount of carbon dioxide increases.