Ciliary activity and pollution

The mucociliary clearance is an important part of the nonspecific defense mechanism of the human airways. Coordinated beats of cilia in the nose, trachea, and bronchi propel the mucous layer toward the pharynx, and with it inhaled microorganisms and other particles captured in the mucus. Normal function of this system depends on the efficacy of the ciliary beating and the properties of mucus. Primary ciliary dyskinesia--a congenital respiratory disease characterized by ultrastructural defects and motility disturbances of cilia--has provided us with valuable information about the role the mucociliary function plays in the protection against harmful agents in the inhaled air. Secondary ciliary dyskinesia is described in inflammatory disorders of the respiratory tract, but also some components in air pollution results in malfunction of cilia, damage of ciliated epithelium, or alteration in the mucus. This review will focus on investigations found in the literature concerning the influence of pollutants on ciliary activity. The methods applied will be evaluated.