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. 2026 Jul 13;14:1890540. doi: 10.3389/fpubh.2026.1890540

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Copyright © 2026 Liu, Ye, Wu, Fang and Mi.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

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Diagram illustrating overlapping supply and demand catchment areas, each marked by circles centered on locations labeled j and k, with arrows indicating distance d sub zero. Solid circles represent town centroids, outlined circles denote health center centroids, dotted lines indicate demand catchment area boundaries, solid lines show supply catchment areas, and dashed lines outline town boundaries. A legend in the lower right explains the symbols and line styles. — The concept of the two-step floating catchment area method.