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. 2021 Feb 17;413:125445. doi: 10.1016/j.jhazmat.2021.125445

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Fig. 6 — Box and whisker plots of O₃ (left panel) and PM2.5 (right panel) levels during weekdays (24-h average) per month for the sites analyzed in Fig. 4, Fig. 5. Median values from these weekdays data were used to calculate percentage difference in O₃ and PM2.5 levels in 2020 relative to 2017–2019. The number below each data box corresponds to the calculated p-value. See text for details.