Unincorporated San Mateo County does not have a standalone leaf blower ordinance, but use is governed by County Code Chapter 4.88 (Noise Control) exterior dBA standards and the statewide AB 1346 ban on new sales of gas-powered small off-road engines (SORE) effective January 1, 2024. Operation must stay within permitted construction hours: 7 AM to 6 PM weekdays, 9 AM to 5 PM Saturdays, and never on Sundays, Thanksgiving, or Christmas.
Leaf blower operation in unincorporated San Mateo County must comply with Chapter 4.88 Noise Control, which sets exterior noise limits at residences ranging from 55 dBA (30+ minutes/hour) up to 75 dBA (1 minute/hour) during daytime, measured within 50 feet of the affected property line. Many gas-powered backpack blowers exceed 70 dBA at 50 feet, making sustained use near homes unlawful. California AB 1346 (Health & Safety Code §43018.11) banned the sale of new gas-powered SORE equipment statewide starting January 1, 2024, implemented by CARB, though existing units may still be used. Bay Area Air Quality Management District (BAAQMD) Spare the Air alerts discourage gas equipment use on flagged days. Many incorporated San Mateo cities (San Mateo, Belmont, Burlingame, Menlo Park) have adopted their own stricter gas-blower phase-outs — unincorporated County residents in pockets surrounded by cities should confirm which rules apply. Battery-electric blowers remain legal subject only to the noise and hour standards.
Violating Chapter 4.88 dBA limits: infraction, $100 first offense, $200 second, $500 subsequent per §4.88.390. Operation outside allowed hours: citation by Sheriff or code enforcement. Sale of new gas SORE equipment: CARB civil penalty.
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See how San Mateo County's leaf blower rules rules stack up against other locations.
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