Montgomery County, MD

ZIP 20839

In ZIP 20839, 3 of the 12 things we check have at least one part graded D or F.

• Drinking water: Loudoun Water - Central System meets every EPA legal limit; 11 contaminants are above health goals, led by pfos at 1.4× California’s Public Health Goal.
• Nearest Superfund site: Hidden Lane Landfill, 4.3 miles away.
• Largest share of modeled toxic air from industry: Micron Technology Inc. (45%), mostly chlorine.
• Fine particles (PM2.5) average 6.9 µg/m³; the WHO guideline is 5 and the EPA annual standard is 9.
• About 70,837 kg of agricultural pesticides are applied in the county each year.

Grades for ZIP 20839

• Superfund sites nearbyC to D
• Factories and industrial sitesA
• Oil and gas wellsA
• Parks and nature nearbyB to C
• Air qualityB
• Drinking water qualityC
• Pesticide useD
• Neighborhood health statusA to B
• Past wildfire impactsA
• Past flood impactsB
• Noise levelsA to D
• Radiation signalsC

Based on 2 census tracts · compiled October 25, 2026 · how each grade works and its sources

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