Decibel Limits: Altadena vs Santa Monica
How do decibel limits rules compare between Altadena, CA and Santa Monica, CA?
Altadena has fewer restrictions than Santa Monica.
Altadena, CA
Los Angeles County
Exterior noise in Altadena's residential zones is capped at 50 dBA daytime / 45 dBA nighttime (single-family); 55/50 dBA (multi-family); 60/55 dBA commercial; 70 dBA all hours industrial.
View full Altadena rules →Santa Monica, CA
Los Angeles County
Santa Monica Municipal Code Section 4.12.060 establishes three noise zones with specific dBA limits. Residential Zone I limits are 50 dBA nighttime and 60 dBA daytime (15-minute Leq). Non-residential Zone II is 60/65 dBA. Industrial Zone III is 70 dBA at all times. A 5 dBA penalty applies for tonal, impulsive, music, or speech content.
View full Santa Monica rules →Key Facts Comparison
| Fact | Altadena | Santa Monica |
|---|---|---|
| Code Section | LA County 12.08.390 | - |
| R-1 Day Limit | 50 dBA | - |
| R-1 Night Limit | 45 dBA | - |
| Multi-family Day/Night | 55 / 50 dBA | - |
| Commercial Day/Night | 60 / 55 dBA | - |
| Zone I Day | - | 60 dBA (15-min Leq) |
| Zone I Night | - | 50 dBA (15-min Leq) |
| Zone II Day | - | 65 dBA (15-min Leq) |
| Code | - | SMMC §4.12.060 |
Highlighted rows indicate differences between cities.
Altadena FAQ
What's the legal decibel limit at my Altadena property line?
50 dBA day / 45 dBA night for single-family residential under LA County Code 12.08.390.
Santa Monica FAQ
What are the noise limits in Santa Monica residential areas?
Noise Zone I (residential) limits are 60 dBA during the day (7 AM–10 PM weekdays, 8 AM–10 PM weekends) and 50 dBA at night, measured as a 15-minute equivalent noise level. These are reduced by 5 dBA for tonal noise, music, or speech.
How is noise measured in Santa Monica?
Using A-weighted decibels (dBA) as a 15-minute equivalent noise level (Leq) and a 5-minute continuous noise level. Measurements are taken at the property line of the affected property.
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