SmogRank / Hacienda Santa Fe / Piedras Negras
Hacienda Santa Fe vs Piedras Negras: PM2.5 compared
Hacienda Santa Fe and Piedras Negras were both measured on only 27 days over the last year, too few to compare them (it takes 30).
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Hacienda Santa Fe
Side by side with Santa Anita (the nearest), Mexicali (Mexico's 2nd worst on 30 days), Gujranwala (the world's worst on 30 days).
Piedras Negras
Side by side with Eagle Pass (the nearest), Gujranwala (the world's worst on 30 days).
The same rules as every SmogRank figure: reference monitors first, and a day counts with 18 measured hours. How we measure.
Updated 2026-10-09 07:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index. Some readings: Uzhydromet (Uzbekistan's Hydrometeorological Service); Department of Environment, Nepal; Vietnam's government monitors; Aurassure; Umhverfisstofnun (Environment Agency of Iceland); Love My Air (City and County of Denver), no reuse terms published (why we use them).