This map shows modeled outdoor noise across March ARB 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 1 March ARB residents, or 0.4%, live above that level. By land area, 25.4% of March ARB is above 55 dBA.
See how noise in March ARB compares to similar-sized cities.
Noise by Part of March ARB
Average noise levels for March ARB residents, grouped by direction from the center of March ARB. Eastern March ARB carries the highest population-weighted average; Western March ARB carries the lowest. Just 2% of residents in Western March ARB live in blocks above the EPA's 55 dBA threshold, roughly the same as the share in Eastern March ARB.
Eastern March ARB
0% of people above 55 dBA
Northern March ARB
0% of people above 55 dBA
Southern March ARB
0% of people above 55 dBA
Western March ARB
2% of people above 55 dBA
Eastern March ARB sounds about 153% louder than Western March ARB to the human ear, a 13.4 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-215 do you need to be?
I-215 produces an estimated 78 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 1% of March ARB sits under tree canopy (much lighter than most cities) and roughly 18% 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.