Why does thermal inversion increases air pollution? What harm can thermal inversion cause to humans?

Thermal inversion confines at low altitude a layer of pollutants that would have been dispersed by the natural upward move of warm air. The solid particles there in the atmosphere cause health problems, like the exacerbation of asthma and other pulmonary diseases, cough, respiratory unease and ocular discharges; later the pollution can also trigger the appearance of cardiovascular and neoplastic diseases.