Recognizing the impact of ambient air pollution on skin health.

Ambient air pollution is a known public health hazard that negatively impacts non-cutaneous organs; however, our knowledge regarding the effects on skin remains limited. Current scientific evidence suggests there are four mechanisms by which ambient air pollutants cause adverse effects on skin health: (i) generation of free radicals, (ii) induction of inflammatory cascade and subsequent impairment of skin barrier, (iii) activation of the aryl hydrocarbon receptor (AhR) and (iv) alterations to skin microflora. In this review, we provide a comprehensive overview on ambient air pollutants and their relevant sources, and highlight current evidence of the effects on skin.