“…Hence, the respiratory system is the main organ affected by air pollution. Numerous epidemiological studies have indicated that air pollutants such as PM, SO 2 , NO 2 , O 3 , and CO are responsible for increasing respiratory morbidity in different populations around the world, especially from the megacities (Çapraz et al, 2017 ; Chang et al, 2020 ; Luo et al, 2018 ; Phosri et al, 2019 ; Phung et al, 2016 ; Qiu et al, 2018 ; Sofwan et al, 2021 ; Vahedian et al, 2017 ). For example, a study conducted by Phung et al ( 2016 ) reported effect estimates (relative risks, RRs) of 1.007 (95% CI 1.002, 1.013), 1.020 (95% CI 1.010, 1.030), and 1.080 (95% CI 1.060, 1.011) for each 10 μg/m 3 increment of PM 10 , SO 2 , and NO 2 , respectively.…”