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. 2021 May 4;291:112676. doi: 10.1016/j.jenvman.2021.112676

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Fig. 4 — The Percent Relative Effect of holidays, lockdown, annual, BLH, local wind components and seasonal factors on NO₂ (a) and PM_2.5 (b) concentrations. The seasonal factor includes monthly variation and the combined influence of RH, T2M, D2M and SP. The holiday and lockdown effects represent the percentage changes of pollutant concentrations relative to the non-holidays and non-lockdowns, the effects of other factors represent the percentage changes of pollutant concentrations during the time interval relative to long-term trends.