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. 2020 Jun 5;739:140000. doi: 10.1016/j.scitotenv.2020.140000

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Fig. 5 — Scatter plots between organic carbon (OC) (A), sulphate (B), nitrate (C), ammonium (D), and elemental carbon (EC) ratios between the observational periods in 2019 and 2020. The colour represents the hour of a day and the dot size represents the scaled levels of O_x (O₃ + NO₂) by EC in 2020 to those in 2019. The black solid lines represent the 1:1 ratio and the grey dash lines represent the ranges of ratio changes for the two periods.