Los Angeles County, CA

ZIP 91748

In ZIP 91748, 9 of the 12 things we check have at least one part graded D or F.

• Drinking water: City Of Brea meets every EPA legal limit; 11 contaminants are above health goals, led by lead at 79× California’s Public Health Goal.
• Nearest Superfund site: San Gabriel Valley (area 4), 0.8 miles away (3 within 10 miles).
• Largest share of modeled toxic air from industry: Sterigenics-Ontario Facility (22%), mostly ethylene oxide.
• Fine particles (PM2.5) average 13.4 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 91748

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

Based on 14 census tracts · compiled September 10, 2026 · how each grade works and its sources

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