Los Angeles County, CA

ZIP 91740

In ZIP 91740, 8 of the 12 things we check have at least one part graded D or F.

• Drinking water: Gswc-San Dimas meets every EPA legal limit; 20 contaminants are above health goals, led by pfos at 3.9× California’s Public Health Goal.
• Nearest Superfund site: San Gabriel Valley (area 2), 5.3 miles away (2 within 10 miles).
• Largest share of modeled toxic air from industry: Sterigenics-Ontario Facility (35%), mostly ethylene oxide.
• Fine particles (PM2.5) average 11.8 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 91740

• Superfund sites nearbyD to F
• Factories and industrial sitesD
• Oil and gas wellsA to C
• Parks and nature nearbyD to F
• Air qualityF
• Drinking water qualityD to F
• Pesticide useB to D
• Neighborhood health statusA to B
• Past wildfire impactsC to F
• Past flood impactsA to C
• Noise levelsA to D
• Radiation signalsC

Based on 13 census tracts · compiled September 10, 2026 · how each grade works and its sources

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