Issue 1 - ¿Update on adverse respiratory effects of outdoor air pollution¿ Part 2): Outdoor air pollution and respiratory diseases: Perspectives from Angola, Brazil, Canada, Iran, Mozambique and Portugal A.C. Sousa; M.R. Pastorinho; M.R. Masjedi; M. Urrutia-Pereira; M. Arrais; E. Nunes; T. To; A.J. Ferreira; C. Robalo-Cordeiro; C. Borrego; J.P. Teixeira; L. Taborda-Barata;

Issue 2 - ¿Update on adverse respiratory effects of indoor air pollution¿. Part 2): Indoor air pollution and respiratory diseases: Perspectives from Italy and some other GARD countries G. Sarno; I. Stanisci; S. Maio; S. Williams; E.M. Khoo; S.G. Diaz; E.V. Ponte; L.T.T. Lan; T. Soronbaev; D. Behera; S. Tagliaferro; S. Baldacci; G. Viegi;

Issue 4¿Impact of air pollution on COVID-19 mortality and morbidity: An epidemiological and mechanistic review Hasan Bayram; Nur Konyalilar; Muge Akpinar Elci; Hadi Rajabi; G. Tu¿e Aksoy; Deniz Mortazavi; Özgecan Kayalar; Öner Dikensoy; Luis Taborda-Barata; Giovanni Viegi;