Characterization of Persistent Air Quality Degradation Episodes of the PM₁₀ in the Metropolitan Area of São Paulo and Their Relationship with Meteorological Conditions

Air pollution is one of the main environmental problems in large urban centers, harming people's health and impacting quality of life. The Metropolitan Area of São Paulo (MASP) presents frequent exceedances of air quality standards of the inhalable particulate matter pollutant (PM₁₀), modulated by meteorological conditions, and its main pollutant sources are vehicular and industrial. This study aims to identify and characterize persistent overtaking episodes due to PM₁₀ in the MASP between 2005 and 2017, relating them to meteorological conditions. The criteria used to select the events were: i) events that occurred in at least 50% of the air quality monitoring stations chosen for this study and, ii) among the events that met the first criterion, those with a duration equal to or greater than the 80% percentile. From the 71 persistent episodes of overtaking selected, the results show that the exceedances of inhalable particulate matter lasted up to 14 consecutive days and were predominant in the austral winter. The peak concentration stage of PM₁₀ episodes were accompanied by an increase in maximum temperature (T), in addition to a decrease in wind speed (WS) and relative humidity (RH), besides the wind direction predominantly from the northwest. These patterns may be related to synoptic prefrontal conditions in the MASP.