This map shows modeled outdoor noise across Snoqualmie Pass 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 10 Snoqualmie Pass residents, or 7.6%, live above that level. By land area, 33.0% of Snoqualmie Pass is above 55 dBA.
See how noise in Snoqualmie Pass compares to similar-sized cities.
Noise by Part of Snoqualmie Pass
Average noise levels for Snoqualmie Pass residents, grouped by direction from the center of Snoqualmie Pass. Southern Snoqualmie Pass carries the highest population-weighted average; Eastern Snoqualmie Pass carries the lowest. Just 0% of residents in Eastern Snoqualmie Pass live in blocks above the EPA's 55 dBA threshold, a fifth of the share in Southern Snoqualmie Pass.
Eastern Snoqualmie Pass
0% of people above 55 dBA
Southern Snoqualmie Pass
10% of people above 55 dBA
Western Snoqualmie Pass
6% of people above 55 dBA
Southern Snoqualmie Pass sounds about 263% louder than Eastern Snoqualmie Pass to the human ear, a 18.6 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 I-90 do you need to be?
I-90 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 quiet suburban street at night.
Calculated from the model's calibrated attenuation formula. About 55% of Snoqualmie Pass sits under tree canopy (heavier than most cities) and roughly 8% 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.