This map shows modeled outdoor noise across Bay Area at 100-meter resolution, combining road, aviation, and rail sources. Green areas measure below 45 dBA. Orange and red exceed the EPA's 55 dBA outdoor threshold linked to long-term health effects. Use the layer toggles to view each source on its own or all together.
What the numbers sound like
- 30 dBAWhisper
- 40 dBASoft rainfall
- 45 dBAQuiet suburban street at night
- 50 dBAQuiet office
- 55 dBAEPA outdoor threshold: light traffic 100 ft away
- 60 dBANormal conversation an arm's length away
- 65 dBABusy restaurant
- 70 dBAHighway traffic 50 ft away
- 80 dBACity bus interior
Population Above the EPA Outdoor Threshold
The EPA's 55 dBA outdoor reference level is a common benchmark for residential noise exposure, especially for activity interference, annoyance, and long-term community noise concerns. About 8,546 Bay Area residents, or 31.8%, live above that level. By land area, 31.8% of Bay Area is above 55 dBA.
See how noise in Bay Area compares to similar-sized neighborhoods.
Noise by Part of Bay Area
Average noise levels for Bay Area residents, grouped by direction from the center of Bay Area. The highest population-weighted average is in southern Bay Area; the lowest is in central Bay Area, where just 24% of residents live in blocks above the EPA's 55 dBA threshold, three-quarters of the share in the loudest section.
Southern Bay Area
31% of people above 55 dBA
Northern Bay Area
22% of people above 55 dBA
Western Bay Area
32% of people above 55 dBA
Southwestern Bay Area
40% of people above 55 dBA
Central Bay Area
24% of people above 55 dBA
To the human ear, noise in southern Bay Area sounds about 31% louder than in central Bay Area, a 3.9 dBA gap. Every 10 dBA roughly doubles perceived loudness. Within any of these directions, two homes a quarter mile apart can still differ by 10 or more dBA depending on how close they sit to a major highway.
How far back from State Hwy 358 do you need to be?
State Hwy 358 produces an estimated 76 dBA at its loudest centerline points. Noise drops logarithmically with distance, with the exact rate depending on what's between you and the road. Tree cover, walls, terrain, and pavement type all matter. At roughly a quarter mile back, traffic fades into the noise level of a soft rainfall.
Calculated from the model's calibrated attenuation formula. About 7% of Bay Area sits under tree canopy (lighter than most neighborhoods) and roughly 46% is impervious surface like pavement and rooftops. Both are folded into the per-place decay rate above. Heavier canopy pulls noise down faster with distance; impervious surfaces slow the drop.