Abstract: The evaluation of air pollution is an important tool for environmental management and public health. In Brazil, air quality policies do not oblige municipalities to monitor air pollutant levels, only states. However, some cities, such as Fortaleza, in the state of Ceará, Brazil, have stood out for implementing air quality monitoring networks. The aim of this study is to assess air quality in the city of Fortaleza, Brazil, by a comparative analysis of local air quality levels in relation to the concentrations established by CONAMA Resolution 491/2018, in parallel with the guide values established by the World Health Organization (WHO) and other national agencies from countries such as the United States, China, India, as well as South American countries and the European Union. The city’s air quality situation was assessed using the levels of particulate matter with aerodynamic sizes of less than 2.5μm (PM2.5) and 10μm (PM10), which were measured by the Fortaleza mobile air quality monitoring station (EMQAr). These parameters were selected because they are the most relevant in terms of human health impact. The pollutant data analyzed refer to the years 2022 and 2023, the post-pandemic period. During these years, the EMQAr was located at 8 strategic points in the city, 4 of which were bus terminals. For the PM2.5 concentrations measured in Fortaleza, there was compliance with the national standards established in the two years evaluated, and the air quality in the region was considered “GOOD” on 98% of the days in 2022 and 100% of the days in 2023. For PM10, air quality was also considered “GOOD” on 98% of the days in 2022 and 99% in 2023. Fortaleza’s air quality complied with the WHO guideline values for 24-hour averages of PM2.5 on 82% and 74% of the days in 2022 and 2023, respectively. For PM10, concentrations in the city met WHO recommendations on 97% and 95% of days in 2022 and 2023, respectively. The levels of PM2.5 and PM10 measured in Fortaleza would be considered within the “GOOD” classification for 100% of the 2022-2023 period according to Chile’s criteria, which has the most flexible levels among the countries studied. Compared to the more restrictive European criteria, air quality would be considered “FAIR” for 80% of the year 2023, in relation to PM2.5, and 84% for PM10. The annual average concentrations of PM2.5 and PM10 were 13μg/m3 and 32μg/m3 (in 2022) and 13μg/m3 and 34μg/m3 (in 2023), respectively. These levels are above the annual guideline values stipulated by the WHO for PM2.5 and PM10 (5μg/m3 and 15μg/m3, respectively), despite being in line with Brazilian legislation (20μg/m3 and 40μg/m3, respectively). It was also noted that the maximum 24-hour concentrations and monthly averages of PM2.5 and PM10 were higher at the city’s urban bus terminals than at the other points monitored, which indicate the need for actions for reducing pollutant levels in these environments, as they are strategic locations for public authorities and have a large number of people circulating daily, which are exposed to these pollution levels.

Keywords: Outdoor Air Quality. Air Quality Index. Particulate matter. Air Quality Standards.