“…Moreover, if it is largely accepted that air pollution may contribute to the pathogenesis of pulmonary diseases, some studies have also highlighted that the expansion of adipose tissue, namely visceral fat, is strongly associated with air pollution-induced lung dysfunction ( Elliot et al., 2019 ; Conti et al., 2018 ; Kim et al., 2017 ; Yang et al., 2019 ), and this is not surprising considering that both fat excess and air pollution-derived lung injury have been linked to increased local and systemic inflammation ( Zhang et al., 2016 ; Bastard et al., 2000 ). In this regard, it has been observed in Asian men that obesity may exhibit a synergistic effect on the relationship between prolonged exposure to air pollutants and worse pulmonary function, suggesting that excessive fat, especially the abdominal one, may intensify the adverse effects of air pollutants on lung function ( Kim et al., 2017 ). Another link between air pollution, obesity and COVID-19 severity may be Vitamin D deficiency; obesity is closely associated with low vitamin D levels, as higher body mass index leads to lower vitamin concentrations ( Barrea et al., 2017 ) and, in light of its largely known and beneficial immunomodulating actions, Vitamin D deficiency may represent an independent risk factor for COVID-19 severity ( Muscogiuri et al., 2020b ; Grant et al., 2020 ).…”