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. 2021 May 24;152(6):455–462. doi: 10.1016/j.adaj.2021.02.013

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Comparison of colony-forming units (CFUs) by treatment periods for zone 1 (horizontal distance, < 2.0 feet; vertical distance, ≈ 3.0 feet), zone 2 (horizontal distance, 2.0-4.0 feet; vertical distance, 3.0 feet), and zone 3 (horizontal distance, > 4.0 feet; vertical distance, 5.0 feet).