Immediate and short-term consequences of secondhand smoke exposure on the respiratory system.

PURPOSE OF REVIEW This review critically evaluates the existing biological evidence regarding the immediate and short-term respiratory consequences of secondhand smoke (SHS). RECENT FINDINGS A 1-h exposure to SHS at bar/restaurant levels generates a marked inflammatory reaction and significant decrements on lung function. These deleterious effects of SHS are exacerbated when physical activity follows the SHS exposure, particularly in less fit individuals. The main respiratory effect mechanisms of SHS include a direct induction of growth factors resulting in airway remodelling and alterations in nitric oxide regulation. Pharmacological agents that increase either apical membrane chloride conductance or basolateral membrane potassium conductance may be of therapeutic benefit in patients with diseases related to SHS exposure. Moreover, treatment with statins has shown beneficial effects towards preventing the SHS-induced pulmonary hypertension, vascular remodelling, and endothelial dysfunction. SUMMARY Based on recently discovered evidence, even brief and short-term exposures to SHS generate significant adverse effects on the human respiratory system. Future research directions in this area include the concentrations of tobacco smoke constituents in the alveolar milieu following SHS exposure, individual susceptibility to SHS, as well as pharmacological treatments for reversing the SHS-induced airway remodelling.