The Air District has issued 3 Notices of Violation to Valero for violations of air quality regulations and/or permit conditions for the May 5 fire. This is an ongoing investigation, and more violations may be issued.
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San Mateo County
Learn about San Mateo County - its climate, potential air pollution concerns, and current air quality. You can also view upcoming Air District events in San Mateo County and read about local efforts to improve air quality.
Latest News
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Air quality advisory for smoke from fire at ValeroMay 05, 2025
The Air District is issuing an air quality advisory for smoke in Southern Solano, northern Contra Costa, and northwestern Alameda counties, specifically communities between I-80 and I-680 bridges (Martinez, Pacheco, Concord and Port Chicago), but with some impact possible southward to Oakland, due to a fire at Valero.
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Spare the Air smog season beginsMay 05, 2025
The Air District is announcing the start of the Spare the Air summer smog season, which runs from May to October in the Bay Area.
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Air District Issues 18 Notices of Violation to Martinez Refining Company as a result of the February 1 fireMay 01, 2025
The Air District has issued 18 Notices of Violation to MRC for violations of air quality regulations and/or permit conditions for the February 1 fire. This is an ongoing investigation, and more violations may be issued.
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Other News Articles
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4/7/2025 Air District to host virtual webinar overview of the proposed budget for Fiscal Year 2025-2026
April 7, 2025
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3/27/2025 Point Richmond and North Richmond Odor
March 27, 2025
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3/25/2025 Air District asks community members to help shape how millions in community funds are spent
March 25, 2025
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3/21/2025 Join Webinar to Explore Careers at the Air District
March 21, 2025
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3/13/2025 Air District’s Clean HEET Program now accepting applications
March 13, 2025
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3/5/2025 Air District launches Charge! Program, expanding Bay Area access to electric vehicle chargers
March 5, 2025
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3/3/2025 Notice Regarding Fraudulent Bay Area Commuter Benefits Program Letters
March 3, 2025
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2/13/2025 MRC Refinery Fire Information
February 13, 2025
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2/1/2025 Air quality advisory for smoke from fire at MRC Refinery in Martinez
February 1, 2025
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1/28/2025 Air District asks public not to light firecrackers and fireworks or burn wood over Lunar New Year holiday
January 28, 2025
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1/22/2025 Air District launches new name and branding
January 22, 2025
San Mateo County lies in the middle of the San Francisco Peninsula, south of San Francisco County, and north of Santa Clara and Santa Cruz counties. It is bounded by the Pacific Ocean to the west and San Francisco Bay to the east. Two San Mateo County representatives sit on the Air District’s Board of Directors.
Climate
Cool, foggy weather is prevalent along the western coast of the peninsula, particularly during the summer. Summertime average daily temperatures are moderate along the west coast and warm in the county’s east side. In the winter, average daily temperatures across the county range from mild to moderate. Winds are mild, with the highest wind speeds focused along the western coast. Rainfall averages about 20 to 25 inches per year at lower elevations and up to 36 inches in the Santa Cruz Mountains.
Interactive Air Monitoring Stations Map
Air Quality in San Mateo County
Ozone and fine particle pollution, or PM2.5, are the major regional air pollutants of concern in the San Francisco Bay Area. Ozone is primarily a problem in the summer, and fine particle pollution in the winter.
In San Mateo County, ozone almost never exceeds health standards, and PM2.5 exceeds the national standard only on about one day each year. San Mateo County frequently receives fresh marine air from the Pacific Ocean, which passes over the coastal hills. In winter, PM2.5 may be transported into San Mateo County from other parts of the Bay Area, adding to wood smoke, which may lead to elevated concentrations, but these are rarely high enough to exceed health standards.
Spare the Air Status
Last Updated: 4/21/2017