A chest infection is an infection that affects your lungs, either in the larger airways (bronchitis) or in the smaller air sacs (pneumonia). There’s a build-up of pus and fluid (mucus), and the airways become swollen, making it a challenge for you to breathe.
Chest infections can affect people of all ages. Young children and the elderly are most at risk, as well as people who are ill and smokers. A chest infection can be serious for these people.