San Mateo County, CA
ZIP 94403
In ZIP 94403, 2 of the 12 things we check have at least one part graded D or F.
- Drinking water: Estero Municipal Improvement District meets every EPA legal limit; 7 contaminants are above health goals, led by chloroform at 107× 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: Tesla Inc. (58%), mostly cobalt compounds.
- Fine particles (PM2.5) average 7.7 µg/m³; the WHO guideline is 5 and the EPA annual standard is 9.
- About 38,964 kg of agricultural pesticides are applied in the county each year.
Grades for ZIP 94403
- Superfund sites nearbyA
- Factories and industrial sitesD to F
- Oil and gas wellsA
- Parks and nature nearbyB to C
- Air qualityB to C
- Drinking water qualityC
- Pesticide useB
- Neighborhood health statusA
- Past wildfire impactsA
- Past flood impactsA
- Noise levelsA to D
- Radiation signalsB to C
Based on 11 census tracts · compiled October 25, 2026 · how each grade works and its sources
Loading the full report, with every source…