Asthma and air pollution: recent insights in pathogenesis and clinical implications

Purpose of review Air pollution has adverse effects on the onset and morbidity of respiratory diseases, including asthma. In this review, we discuss recent insights into the effects of air pollution on the incidence and exacerbation of asthma. We focus on epidemiological studies that describe the association between air pollution exposure and development, mortality, persistence and exacerbations of asthma among different age groups. Moreover, we also provide an update on translational studies describing the mechanisms behind this association. Recent findings Mechanisms linking air pollutants such as particulate matter, nitrogen dioxide (NO2) and ozone to the development and exacerbation of asthma include the induction of both eosinophilic and neutrophilic inflammation driven by stimulation of airway epithelium and increase of pro-inflammatory cytokine production, oxidative stress and DNA methylation changes. Although exposure during foetal development is often reported as a crucial timeframe, exposure to air pollution is detrimental in people of all ages, thus influencing asthma onset as well as increase in asthma prevalence, mortality, persistence and exacerbation. In conclusion, this review highlights the importance of reducing air pollution levels to avert the progressive increase in asthma incidence and morbidity.