Air Quality Index in San Francisco, CA
San Francisco is a vibrant city known for its iconic landmarks like the Golden Gate Bridge and Alcatraz Island. It has a mild climate but air quality can vary. The air quality index in San Francisco is often good but during certain times especially in the summer and fall wildfires nearby can cause air pollution leading to poor air quality.
Air Quality Index
February 16, 2025Air quality is ideal, with minimal or no risk to health.
Air Quality Index
February 17, 2025Air quality is acceptable, but some individuals, particularly those unusually sensitive to air pollution, may experience minor health effects.
Air Quality Index
February 18, 2025Members of sensitive groups, such as children, the elderly, and individuals with respiratory conditions, may experience adverse health effects. The general population is less likely to be affected.
Air Quality Index
February 19, 2025Air quality is acceptable, but some individuals, particularly those unusually sensitive to air pollution, may experience minor health effects.
Air Quality Index
February 20, 2025Members of sensitive groups, such as children, the elderly, and individuals with respiratory conditions, may experience adverse health effects. The general population is less likely to be affected.
Air Quality Index
February 21, 2025Air quality is acceptable, but some individuals, particularly those unusually sensitive to air pollution, may experience minor health effects.
5-Day Air Quality Index Forecast in San Francisco, CA
Nitrogen dioxide is a reddish-brown gas formed primarily from the combustion of fossil fuels, especially from vehicles, power plants, and industrial processes.
Ozone is a gas composed of three oxygen atoms, formed in the atmosphere through chemical reactions between volatile organic compounds (VOCs) and nitrogen oxides (NOₓ) in the presence of sunlight.
PM2.5 refers to airborne particles with a diameter of 2.5 micrometers or smaller, consisting of various components like dust, soot, and liquid droplets, often originating from combustion and chemical reactions in the atmosphere.
M10 refers to particulate matter with a diameter of 10 micrometers or smaller, typically including dust, pollen, and mold spores, originating from construction, road dust, and natural sources.
Tips to Protect Yourself from Unhealthy Air Quality in San Francisco, CA

Close all windows and doors to keep polluted air from coming inside. If possible, use an air purifier to remove harmful particles from the indoor air.

If you need to go outside, wear a high-quality mask like an N95 or KN95. These masks are designed to filter out tiny particles in the air, including smoke and dust.

Pay attention to local air quality reports and limit your time outside if the air quality index is unhealthy.
FAQ
Frequently Asked Questions-
When is AQI usually the worst in San Francisco?
Air quality in San Francisco is typically at its worst during the winter months, particularly in January, November, and December. These months often experience higher levels of particulate matter (PM2.5) due to increased heating and wood burning, as well as thermal inversions that trap air pollution near the ground.
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What are common pollutants that impact AQI in San Francisco?
The main pollutants affecting air quality in San Francisco include particulate matter (PM2.5 and PM10), nitrogen oxides (NOₓ), carbon monoxide (CO), Sulfur dioxide (SO₂) and volatile organic compounds (VOCs).
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Are there specific areas in San Francisco, CA with better AQI?
Air quality can vary across different neighborhoods in San Francisco due to factors like traffic density, industrial activities, and local weather patterns. Generally, areas with less vehicular traffic and fewer industrial sources tend to have better air quality. For instance, neighborhoods like the Richmond District and parts of the Sunset District often experience better air quality compared to areas near major highways or industrial zones. However, air quality can change rapidly, so it's advisable to check real-time air quality data for specific locations.
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