San Luis Obispo County, CA

ZIP 93420

In ZIP 93420, 7 of the 12 things we check have at least one part graded D or F.

• Drinking water: Woodlands Development meets every EPA legal limit; 11 contaminants are above health goals, led by lead at 35× California’s Public Health Goal.
• Closer to Superfund sites than 0% of U.S. neighborhoods, with no listed site within 10 miles of its center.
• Largest share of modeled toxic air from industry: Phillips 66 Co-Santa Maria Refinery (100%), mostly hydrogen sulfide.
• Fine particles (PM2.5) average 7.3 µg/m³; the WHO guideline is 5 and the EPA annual standard is 9.
• About 901,427 kg of agricultural pesticides are applied in the county each year.

Grades for ZIP 93420

• Superfund sites nearbyA
• Factories and industrial sitesB to C
• Oil and gas wellsA to D
• Parks and nature nearbyB to F
• Air qualityA to C
• Drinking water qualityB to F
• Pesticide useF
• Neighborhood health statusB to D
• Past wildfire impactsC to F
• Past flood impactsB to C
• Noise levelsA to B
• Radiation signalsC to D

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

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