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. 2021 May 15;789:147739. doi: 10.1016/j.scitotenv.2021.147739

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Fig. 3 — Percentage change of (a) observed daytime average O_x (NO₂ + O₃), whole-day average (b) NO₂, (c) CO, (d) SO₂, (e) PM_2.5, and (f) PM₁₀ concentrations during the CLD period relative to the pre-CLD period.