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. 2021 Mar 4;28(16):19615–19628. doi: 10.1007/s11356-021-13208-x

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© The Author(s) 2021

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Fig. 1 — NO²⁻ nitrogen dioxide, SO₂ sulfur dioxide, VOCs volatile organic compounds, CO carbon monoxide, PM2.5 particulate matter with diameter < 2.5 μm in diameter, PM10 particulate matter with diameter < 10 μm in diameter