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. 2018 Jul 18;4(7):eaat1613. doi: 10.1126/sciadv.aat1613

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Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).

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Fig. 2 — (A) Mean estimate and 95% confidence intervals for the effect of maximum ozone on visitation by season. (B) Seasonal histograms of maximum ozone. The red line indicates the 70-ppb threshold. (C) Seasonal histograms of average monthly exceedance days. ***P < 0.01, **P < 0.05, and *P < 0.1.