Middlesex County, MA

ZIP 02421

In ZIP 02421, 3 of the 12 things we check have at least one part graded D or F.

• Drinking water: Waltham Water Department meets every EPA legal limit; 2 contaminants are above health goals, led by chloroform at 106× California’s Public Health Goal.
• Nearest Superfund site: Hanscom Field/hanscom Air Force Base, 2.8 miles away (3 within 10 miles).
• Largest share of modeled toxic air from industry: Tecomet (44%), mostly cobalt.
• Fine particles (PM2.5) average 6.7 µg/m³; the WHO guideline is 5 and the EPA annual standard is 9.
• About 34,462 kg of agricultural pesticides are applied in the county each year.

Grades for ZIP 02421

• Superfund sites nearbyD to F
• Factories and industrial sitesF
• Oil and gas wellsA
• Parks and nature nearbyB
• Air qualityB
• Drinking water qualityA to C
• Pesticide useA to C
• Neighborhood health statusA
• Past wildfire impactsA
• Past flood impactsC
• Noise levelsA to C
• Radiation signalsC to F

Based on 5 census tracts · compiled October 25, 2026 · how each grade works and its sources

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