Infographic: Deaths linked to outdoor and indoor air pollution

Pneumonia is a form of acute respiratory infection that is most commonly caused by viruses or bacteria. It can cause mild to life-threatening illness in people of all ages, however it is the single largest infectious cause of death in children worldwide.

Pneumonia killed more than 808 000 children under the age of 5 in 2017, accounting for 15% of all deaths of children under 5 years.  People at-risk for pneumonia also include adults over the age of 65 and people with preexisting health problems.

The lungs are made up of small sacs called alveoli, which fill with air when a healthy person breathes. When an individual has pneumonia, the alveoli are filled with pus and fluid, which makes breathing painful and limits oxygen intake. These infections are generally spread by direct contact with infected people.

Vaccines can help prevent pneumonia.