Impact of environmental factors on lung defences

The lungs are one of the most important organs exposed to environmental agents. The lungs have the ability to protect themselves by both immunological and nonimmunological mechanisms. An individual’s susceptibility to the impact of environmental agents will determine their adverse effects. This article focuses on air pollution, in particular ozone (O3), nitrogen dioxide (NO2), particulate matter (PM) and sulphur dioxide (SO2). O3 inhalation first modifies the ciliary cells. O3 is an extremely strong oxidant, since it increases the permeability of epithelial cells and decreases mucociliary clearance. NO2 is a less potent and less reactive oxidant pollutant and impairs the function of epithelial cells and alveolar macrophages. PM induces oxidative stress in macrophages and epithelial cells, and increases tumour necrosis factor-b, interleukin (IL)-6, interferon-c, transforming growth factor-b and nuclear factor-kB. Diesel exhaust particulate, contained in PM, increases IL-8 production. High concentrations of SO2 increase the production of reactive oxygen species in the lungs. In conclusion, air pollution certainly interferes with aspecific and specific lung defences, thus facilitating the development of pulmonary diseases, such as exacerbation of chronic obstructive pulmonary disease, allergies and asthma.