Los Angeles County Decibel Limits Rules (2026) — What You Need to Know

LA County's decibel limits under Section 12.08.390 are zone-specific and unusually precise for a county-level ordinance. Residential zones — which cover the vast majority of unincorporated neighborhoods — are limited to 50 dB during the day (7 AM to 10 PM) and 45 dB at night (10 PM to 7 AM). To put that in perspective, 45 dB is roughly the level of a quiet library, and 50 dB is a normal conversation at home.

Commercial zones get a 10 dB bump: 60 dB during the day and 55 dB at night. Industrial zones are set at 70 dB around the clock, reflecting the higher baseline noise in manufacturing and warehouse districts.

The county uses a 30-minute cumulative measurement period within any given hour. This means a single brief spike won't necessarily trigger a violation, but sustained noise above the limit will. Enforcement officers use calibrated sound level meters and take readings at the property line of the affected residence or business. The cumulative approach prevents trivial complaints about momentary sounds like car doors or short phone conversations outdoors.

These limits are notably strict compared to most California jurisdictions. Many cities allow 55-65 dB during the day in residential zones. LA County's 50 dB daytime residential cap means that everyday activities like running a generator, operating a workshop, or even having a loud conversation on your patio could exceed the limit if audible at the property line.