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. 2020 May 28;737:139765. doi: 10.1016/j.scitotenv.2020.139765

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Fig. 3 — NMHC/NO_x concentration ratios (calculated using ppmC and ppm units for NMHC and NO_x, respectively) determined at a) Irajá monitoring station; b) Bangu monitoring station from March 1 to April 16, 2020. The periods of time are indicated in different colors: before the partial lockdown (03/01/2020–03/22/2020); partial lockdown (03/23/2020–04/05/2020); relaxed partial lockdown (04/06/2020–04/16/2020).