Los Angeles County, CA

ZIP 91766

In ZIP 91766, 9 of the 12 things we check have at least one part graded D or F.

• Drinking water: Chino Hills, City Of has 1 contaminant at or over an EPA legal limit; 14 contaminants are above health goals, led by arsenic at 2,764× California’s Public Health Goal.
• Nearest Superfund site: San Gabriel Valley (area 4), 9.2 miles away.
• Largest share of modeled toxic air from industry: Sterigenics-Ontario Facility (63%), mostly ethylene oxide.
• Fine particles (PM2.5) average 13.9 µg/m³; the WHO guideline is 5 and the EPA annual standard is 9.
• About 250,208 kg of agricultural pesticides are applied in the county each year.

Grades for ZIP 91766

• Superfund sites nearbyA to C
• Factories and industrial sitesD to F
• Oil and gas wellsF
• Parks and nature nearbyB to D
• Air qualityF
• Drinking water qualityC to F
• Pesticide useA to C
• Neighborhood health statusA to D
• Past wildfire impactsD
• Past flood impactsC
• Noise levelsA to D
• Radiation signalsC to D

Based on 16 census tracts · compiled October 25, 2026 · how each grade works and its sources

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