The pulmonary pathology of air pollution: a review

Exposure to ambient and household air pollution causes respiratory disease at all stages of life and is globally responsible for 6.7 million premature deaths annually. The major known contributory pollutants are PM, SO₂, O₃, NO₂ and CO. Extensive evidence has been published describing their various pathological effects. The WHO report that 99% of the earth's population breathe air with pollution levels outside the global air quality guidelines. Lack of access to clean fuel is a major risk factor, particularly in low- and middle-income countries. The effects of pollution on the respiratory system are broad, identified from intrauterine life to old age, with most risk at the extremes of age. Many pollutants damage the airways by the same mechanism; the induction of oxidative stress and production of reactive oxygen and nitrogen species, leading to chronic airway changes. Pathologies related to environmental pollution include, but are not limited to, defects in lung development, asthma and COPD, infectious disease and respiratory tract malignancies. While the cardiovascular effects of exposure to pollution have been well described, the purpose of this review article is to outline the major ambient air pollutant types associated with respiratory disease, and describe the pulmonary pathology associated with their exposure.