Chronic bronchitis is the production of increased mucus caused by inflammation. Bronchitis is considered chronic if you cough and produce excess mucus most days for three months in a year, two years in a row.
Chronic bronchitis doesn't strike suddenly. After a winter cold seems cured, you may continue to cough and produce large amounts of mucus for several weeks. Since people who get chronic bronchitis are often smokers, the cough is usually dismissed as only "smoker's cough."
As time goes on, colds become more damaging. Coughing and bringing up phlegm last longer after each cold. Without realizing it, you may begin to take this coughing and mucus production as a matter of course, all year long. Generally, the cough is worse in the morning and in damp, cold weather. You may cough up an ounce or more of yellow mucus each day.