“…At the same time, we sought to meet the recommendations proposed by the WHO in its recent air quality guide (WHO, 2021), and to evaluate small and medium-sized cities with characteristic levels of pollution, greatly differentiating the classic studies performed in large urban centers. After the disclosure of this concern, there has been a growing number of studies investigating these areas and smaller cities ( Jesenko et al, 2022 ; Tavella et al, 2022a , 2022b ; Trček, 2022 ).…”