*2.2.2 PM and O3 concentration data*

The RAMA network includes 44 air quality monitoring stations covering the entire Mexico City metropolitan area. It reports hourly concentrations of O3, NO2, NOx, NO, SO2, CO, PM10, and PM2.5 [16]. We selected eight stations (**Figure 1**) with data for the period 2012–2022. Two stations (MER and HGM) are in urban areas and report PM10, PM2.5, and O3 concentrations. We selected two stations located in rural areas (ACO and UAX), which report PM10 and O3 and PM2.5 and O3 concentrations, respectively. Stations CHO, CUA, CCA, and SFE are in semi-urban areas, and the first two report PM10 and O3 concentrations, while the other two reports PM2.5 and O3 concentrations.

#### **2.3 Methodology**

Hourly and monthly averages of PM (10 and 2.5) and ozone concentrations in urban, rural, and semi-urban areas were obtained to define the diurnal and monthly cycles of these pollutants. Similarly, hourly and monthly averages of meteorological data from REDMET were obtained to study the effect of meteorological conditions on PM and ozone concentrations.

The effect of mobility restrictions in 2020 on PM and O3 concentrations, which can be considered as a major public policy intervention, was evaluated using the Mann-Kendall trend analysis with Sen's slope [17]. In addition, the Chow [18] test, which is used to test whether a break occurs at a given time in a time series, was

### *Air Quality in Mexico City after Mayor Public Policy Intervention DOI: http://dx.doi.org/10.5772/intechopen.111558*

used to assess the effect of the 2020 mobility restrictions. Statistical significance of PM concentration differences was assessed using the nonparametric Mann-Whitney U test, which is commonly used in air quality studies to compare differences in pollutant levels [19, 20]. A 95% significance level (p < 0.05) was used for all tests. Finally, the number of days exceeding the national air quality standard is used to determine the effect of public policy intervention on PM concentrations in GMC.
