How to Monitor Air Quality Alerts in San Francisco

San Francisco, renowned for its iconic skyline, fog-draped hills, and progressive environmental policies, is also a city increasingly affected by air quality fluctuations. From wildfire smoke drifting in from Northern California to localized emissions from traffic and industrial activity, the air residents breathe can vary dramatically from day to day. Monitoring air quality alerts in San Francisco is no longer optional—it’s a critical part of daily life for health-conscious individuals, families with children or elderly members, outdoor workers, and those with respiratory conditions like asthma or COPD.

Air quality alerts serve as early warning systems, helping people make informed decisions about outdoor activities, commuting, and even indoor ventilation. In a city where proximity to nature and outdoor recreation are central to quality of life, understanding how to access, interpret, and respond to these alerts can mean the difference between a healthy day and a health crisis.

This guide provides a comprehensive, step-by-step roadmap for monitoring air quality alerts in San Francisco. Whether you’re a long-time resident, a new arrival, or someone managing a chronic health condition, this tutorial will equip you with the knowledge, tools, and best practices to stay safe and informed—no matter the season or environmental challenge.

Step-by-Step Guide

Step 1: Understand the Air Quality Index (AQI)

Before you can effectively monitor air quality, you must understand the metric used to communicate it: the Air Quality Index (AQI). The AQI is a standardized scale developed by the U.S. Environmental Protection Agency (EPA) to report daily air quality. It measures five major pollutants regulated under the Clean Air Act: ground-level ozone, particulate matter (PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide.

The AQI ranges from 0 to 500, with higher values indicating greater health concern. It is divided into six color-coded categories:

• 0–50 (Green) – Good air quality; minimal impact.
• 51–100 (Yellow) – Moderate; acceptable, but a few pollutants may pose a moderate health concern for a very small number of people.
• 101–150 (Orange) – Unhealthy for sensitive groups; children, older adults, and people with heart or lung disease should limit prolonged outdoor exertion.
• 151–200 (Red) – Unhealthy; everyone may begin to experience health effects; members of sensitive groups may experience more serious effects.
• 201–300 (Purple) – Very unhealthy; health warnings of emergency conditions; the entire population is more likely to be affected.
• 301–500 (Maroon) – Hazardous; health alert: everyone may experience more serious health effects.

For San Francisco residents, PM2.5 (fine particulate matter) is often the most concerning pollutant, especially during wildfire season. These tiny particles can penetrate deep into the lungs and bloodstream, triggering inflammation and worsening respiratory and cardiovascular conditions.

Step 2: Identify Local Monitoring Sources

San Francisco benefits from a robust network of air quality monitoring stations operated by regional agencies. The primary sources for real-time and forecasted data include:

• Bay Area Air Quality Management District (BAAQMD) – The official regional agency responsible for monitoring and regulating air pollution across the nine Bay Area counties, including San Francisco.
• U.S. Environmental Protection Agency (EPA) AirNow – A national platform that aggregates data from local monitors and provides a user-friendly interface.
• PurpleAir – A community-driven network of low-cost sensors that offer hyperlocal, real-time data, often filling gaps where official stations are sparse.
• California Air Resources Board (CARB) – Provides statewide data and policy context that can help interpret regional trends.

Each of these sources offers different strengths. BAAQMD provides legally recognized, high-precision data. AirNow offers simplicity and national consistency. PurpleAir delivers neighborhood-level granularity, which is especially useful in areas like the Mission District or the Richmond where local emissions may differ from citywide averages.

Step 3: Set Up Real-Time Alerts via Mobile Apps

One of the most effective ways to monitor air quality is through smartphone applications that push notifications based on your location. Here’s how to set them up:

1. Download the AirVisual app (by IQAir) or the BAAQMD AirAlert app. Both are available on iOS and Android.
2. Enable location services so the app can detect your current position and provide alerts specific to your neighborhood.
3. Set alert thresholds – For example, configure the app to notify you when AQI exceeds 100 (Orange) if you have asthma, or 150 (Red) for general awareness.
4. Enable push notifications for daily forecasts and emergency alerts during wildfire events.
5. Check the app daily as part of your morning routine, especially from June through November, when wildfire smoke is most common.

Many users find that combining two apps—such as AirVisual for detailed data and BAAQMD for official advisories—provides the most complete picture. The BAAQMD app also includes historical trends and pollutant breakdowns, which are invaluable for identifying patterns over time.

Step 4: Subscribe to Email and Text Alerts

Not everyone relies on apps. For those who prefer email or SMS, several agencies offer free subscription services:

• BAAQMD AirAlert Email Notifications – Visit baaqmd.gov, navigate to “Air Quality Alerts,” and sign up for daily forecasts and emergency alerts. You can choose to receive alerts for the entire Bay Area or specific zones like San Francisco.
• EPA AirNow Email Alerts – Go to airnow.gov, click “Subscribe,” and enter your ZIP code (e.g., 94105 for downtown SF). You’ll receive daily summaries and forecast changes.
• City of San Francisco Emergency Alerts – Enroll in NotifySF, the city’s official emergency notification system. While primarily for earthquakes and fires, it often includes air quality emergency advisories during extreme events.

Text alerts are particularly useful during rapid-onset events like sudden wildfire smoke events. BAAQMD offers SMS alerts for “Air Quality Alerts” and “Smoke Advisories.” Simply text “BAQ” to 888-777 to opt in (standard message and data rates apply).

Step 5: Learn to Interpret Hourly and Forecasted Data

AQI data isn’t static—it changes throughout the day. Understanding how to interpret hourly trends and 24-hour forecasts is essential for planning.

For example, ozone levels typically peak in the afternoon during summer due to sunlight reacting with vehicle emissions. If you’re planning a midday run, check if ozone is elevated—even if the overall AQI appears moderate. Conversely, PM2.5 from wildfire smoke can linger for days, often peaking overnight and remaining high through the morning.

Use the BAAQMD “Air Quality Forecast” page to view predicted AQI levels for the next 5 days. During wildfire season, forecasts may show “High Risk” or “Very High Risk” categories, indicating potential for AQI values over 200. These forecasts are updated twice daily and incorporate weather models, fire activity, and wind patterns.

Tip: Look for the “Primary Pollutant” designation on each alert. If it says “PM2.5,” you’re dealing with smoke. If it says “Ozone,” it’s likely a heat-related pollution event. The response differs: for smoke, seal windows and use air purifiers; for ozone, avoid strenuous outdoor activity between 12 p.m. and 8 p.m.

Step 6: Use Indoor Air Quality Monitoring Devices

Outdoor alerts are only half the story. Indoor air quality can be just as critical, especially in older buildings with poor ventilation. Consider investing in a home air quality monitor that measures PM2.5, VOCs, and humidity.

Popular options include:

• Awair Element – Tracks PM2.5, CO2, temperature, and humidity with a clean app interface.
• Temtop M10 – Affordable, portable, and accurate for PM2.5 detection.
• Netatmo Weather Station – Includes an air quality module that syncs with your smartphone.

Place the device in your main living area or bedroom. If indoor PM2.5 levels exceed 35 µg/m³ (the WHO 24-hour guideline), it’s time to activate your air purifier or close windows—even if the outdoor AQI appears acceptable. Smoke particles can infiltrate homes through gaps in windows, doors, and HVAC systems.

Step 7: Adjust Daily Habits Based on Alerts

Monitoring is only useful if it leads to action. Here’s how to adapt your routine:

• AQI 0–100 (Green/Yellow) – Normal activities; no restrictions.
• AQI 101–150 (Orange) – Sensitive groups should reduce prolonged outdoor exertion. Consider indoor workouts or early morning/evening outdoor time.
• AQI 151–200 (Red) – Everyone should limit outdoor activity. Avoid exercise outdoors. Keep windows closed. Use recirculating mode on HVAC systems.
• AQI 201+ (Purple/Maroon) – Stay indoors as much as possible. Avoid driving unless necessary. If you must go out, wear an N95 or KN95 mask. Check on neighbors, especially elderly or immunocompromised individuals.

During extended smoke events, schools and workplaces may issue advisories. Stay informed through local news and official channels. Many employers in San Francisco now offer remote work options during high-pollution days—a benefit worth asking about if you’re affected.

Step 8: Monitor School and Community Advisories

San Francisco Unified School District (SFUSD) and other public institutions issue air quality guidance during elevated pollution events. Parents should:

• Check the SFUSD website for air quality updates during wildfire season.
• Subscribe to school district alerts via email or text.
• Know the district’s policy on outdoor recess and physical education during poor air quality days.

Community centers, libraries, and senior centers often become “clean air shelters” during extreme events. These locations have high-efficiency air filtration systems and are open to the public when AQI reaches hazardous levels. Keep a list of nearby shelters—such as the Main Library on 100 Larkin Street or the Mission Branch Library—saved in your phone.

Best Practices

Practice Daily Awareness

Don’t wait for an alert to check air quality. Make it a habit to review the AQI during your morning routine—just as you would check the weather. Consistent awareness builds resilience and reduces panic during emergencies.

Keep a Personal Air Quality Log

Use a simple notebook or digital spreadsheet to record daily AQI levels, symptoms you experience (e.g., coughing, wheezing, headaches), and actions you took. Over time, this log can reveal patterns—such as how your asthma flares when PM2.5 exceeds 50 µg/m³—and help you communicate more effectively with your healthcare provider.

Invest in a High-Quality Air Purifier

For homes and offices, a HEPA-filter air purifier is one of the most effective tools for reducing indoor exposure. Look for models with a Clean Air Delivery Rate (CADR) of at least 240 for a typical living room. Place the unit in your bedroom for overnight protection, and run it continuously on low or medium during high-pollution periods.

Seal Gaps in Your Home

Even small openings can let smoke infiltrate. Use weatherstripping around windows and doors, and seal gaps around vents and utility penetrations. During smoke events, turn off exhaust fans that pull air in from outside (e.g., kitchen range hoods), and switch your HVAC system to recirculation mode.

Wear Proper Respiratory Protection

When outdoor exposure is unavoidable, wear an N95 or KN95 mask. Surgical masks and cloth masks offer little protection against PM2.5. Ensure the mask fits snugly over your nose and chin. The CDC recommends N95s for use during wildfire smoke events.

Stay Informed About Regional Fire Activity

Wildfire smoke in San Francisco often originates from fires hundreds of miles away. Monitor the California Department of Forestry and Fire Protection (CAL FIRE) incident map and the Incident Information System to understand the source and trajectory of smoke. Wind patterns matter: northerly winds bring smoke from the North Coast, while easterly winds can carry smoke from the Sierra Nevada.

Advocate for Cleaner Air

Individual action is powerful, but systemic change is essential. Support policies that reduce emissions from transportation, promote clean energy, and expand urban green space. Attend BAAQMD public meetings, write to your city councilmember, or join local environmental groups like Clean Air Task Force or SF Environment.

Prepare for Extended Events

During multi-day smoke events, stock up on essentials: bottled water, non-perishable food, batteries, and N95 masks. Keep a portable air purifier or HEPA filter for your car if you commute. Have a backup plan for childcare or work if schools or offices close due to air quality.

Tools and Resources

Official Government Platforms

• Bay Area Air Quality Management District (BAAQMD) – The authoritative source for air quality data, forecasts, regulations, and public advisories in San Francisco and the Bay Area. Offers real-time maps, historical data, and detailed pollutant breakdowns.
• EPA AirNow – A national platform that aggregates data from local monitors. Provides easy-to-read color-coded maps and forecast tools. Ideal for quick checks and sharing with family members.
• California Air Resources Board (CARB) – Offers statewide air quality trends, emissions inventories, and policy updates. Useful for understanding long-term changes and regulatory context.
• NotifySF – The City of San Francisco’s emergency alert system. Includes air quality emergencies when declared by public health officials.

Third-Party Apps and Websites

• IQAir AirVisual – One of the most accurate and user-friendly air quality apps globally. Offers hourly forecasts, historical trends, and global comparisons. Highly recommended for San Francisco residents.
• PurpleAir – A network of over 10,000 community-operated sensors. Provides hyperlocal data down to the street level. Use the “Map” feature to compare readings from sensors near your home, workplace, or school. Note: PurpleAir data requires calibration and should be cross-referenced with official sources.
• Windy.com – A weather visualization tool that includes smoke plume forecasts. Excellent for understanding how smoke moves across the region over time.
• OpenAQ – An open-source global air quality database. Useful for researchers and those interested in comparing San Francisco’s data with other cities.

Hardware Recommendations

• Indoor Air Monitors – Awair Element, Temtop M10, or Foobot for real-time PM2.5 and VOC tracking.
• Air Purifiers – Coway Airmega 400S, Blueair Blue Pure 211+, or Levoit Core 400S (all with true HEPA filters).
• Respiratory Protection – 3M N95 8210, Honeywell H910, or 3M 8511 (for extended wear). Avoid cloth masks and surgical masks for smoke protection.
• Smart Thermostats – Ecobee or Nest with air quality sensors can auto-switch to recirculation mode when pollutants rise.

Community and Educational Resources

• San Francisco Department of Public Health (SFDPH) Air Quality Page – Offers health advisories, fact sheets, and tips for vulnerable populations.
• American Lung Association – State of the Air Report – Annual rankings of U.S. cities for air pollution. San Francisco has improved over the last decade but still faces challenges during wildfire season.
• University of California, Berkeley – Air Quality Research Group – Publishes peer-reviewed studies on local pollution sources and mitigation strategies.

Real Examples

Example 1: The 2020 August Complex Fire Event

In September 2020, the August Complex Fire in Northern California generated a massive smoke plume that blanketed the Bay Area for over a week. On September 10, the AQI in downtown San Francisco reached 375—“Hazardous” by EPA standards. Schools closed. Outdoor events were canceled. Many residents reported burning eyes, coughing, and difficulty breathing.

Residents who had already set up AirVisual alerts received push notifications hours before the smoke arrived, allowing them to seal windows, activate air purifiers, and reschedule outdoor plans. Those who relied solely on weather apps were caught off guard. The BAAQMD issued a “Smoke Advisory” and activated its emergency response protocol, including public advisories on social media and local radio.

Post-event analysis showed that neighborhoods with higher tree canopy coverage (e.g., the Sunset District) experienced slightly lower PM2.5 levels than downtown areas, underscoring the role of urban greening in mitigating pollution.

Example 2: Daily Ozone Peaks in the Mission District

In summer 2023, a resident in the Mission District noticed consistent afternoon coughing and wheezing. Using PurpleAir, she discovered that her neighborhood’s PM2.5 levels were normal, but ozone readings spiked between 2 p.m. and 6 p.m. She cross-referenced with BAAQMD data and confirmed elevated ozone due to traffic congestion on Mission Street and nearby freeways.

She adjusted her routine: moved her evening walk to 7 a.m., used a HEPA air purifier in her home, and started biking to work on weekends to reduce exposure. Within two weeks, her symptoms improved significantly. She shared her findings with her neighborhood association, prompting a discussion about traffic-calming measures and green infrastructure.

Example 3: A Senior Citizen’s Smoke Preparedness Plan

Mr. Thompson, 78, lives alone in the Richmond District and has COPD. He signed up for BAAQMD email alerts and NotifySF. He purchased a Honeywell air purifier and keeps N95 masks in his bedside drawer. During the 2022 Kincade Fire event, he received an alert at 8 a.m. that AQI was projected to reach 210 by noon.

He closed all windows, turned on his purifier, and called his daughter to ask her to bring groceries. He avoided going out for three days. His doctor later praised his proactive approach, noting that he avoided an emergency room visit that many others with similar conditions experienced.

Example 4: A School Teacher’s Classroom Adaptation

Ms. Rivera teaches 4th grade at a public school in the Outer Sunset. When AQI reached 175 during a 2021 smoke event, she followed SFUSD guidelines and moved all physical activities indoors. She used a portable air purifier in her classroom and created a “Clean Air Day” lesson plan on how pollution affects lungs. Her students created posters about wearing masks and keeping windows closed.

Parents thanked her for keeping children safe and informed. The school later installed HEPA filters in all classrooms—a direct result of community feedback during the smoke event.

FAQs

How often should I check the air quality in San Francisco?

Check daily during wildfire season (June–November) and during heatwaves (May–September). Outside these periods, checking once or twice a week is sufficient unless you have a health condition that makes you sensitive to pollution.

Are air quality alerts different in different parts of San Francisco?

Yes. Areas near freeways (e.g., I-280, US-101) or industrial zones (e.g., Candlestick Point) often have higher ozone and NOx levels. Neighborhoods with more trees and open space (e.g., Golden Gate Park, Presidio) may have slightly cleaner air. Use PurpleAir or BAAQMD’s interactive map to compare readings by ZIP code.

Can I rely on weather apps like Apple Weather or Google Weather for air quality?

Some weather apps include AQI data, but they often use outdated or averaged information. For accuracy and timeliness, use dedicated air quality platforms like AirVisual, BAAQMD, or AirNow.

What should I do if my air purifier doesn’t reduce indoor PM2.5?

Ensure the unit is properly sized for your room. Check that filters are replaced every 6–12 months. Seal windows and doors. Turn off exhaust fans that pull in outside air. If levels remain high, consider upgrading to a higher-CADR model or adding a second unit.

Do masks really help during wildfire smoke?

Yes—N95 and KN95 masks are proven to filter out 95% of PM2.5 particles. Cloth and surgical masks offer minimal protection. Always ensure a tight seal around your nose and chin.

Is indoor air quality worse than outdoor during smoke events?

It can be. Smoke can infiltrate buildings through gaps and HVAC systems. Without filtration, indoor PM2.5 levels can reach 70–90% of outdoor levels. Using a HEPA air purifier reduces this to 20–30%.

Where can I find real-time wildfire smoke maps for San Francisco?

Visit Windy.com and select “Smoke” under the layers menu. BAAQMD’s “Air Quality Map” also includes smoke plume overlays during active fire events.

Should I exercise outdoors when the AQI is moderate?

If you’re healthy, light to moderate outdoor activity is generally safe at AQI 51–100. If you have asthma, COPD, heart disease, or are pregnant, reduce exertion and avoid peak afternoon hours when ozone is highest.

How long do air quality alerts typically last?

Most alerts last 1–3 days. During major wildfire events, they can persist for over a week. Always monitor forecasts—conditions can improve rapidly with wind shifts or rain.

Can children and pets be affected by poor air quality?

Yes. Children’s developing lungs are more vulnerable. Pets, especially brachycephalic breeds (e.g., bulldogs, pugs), are also at risk. Keep them indoors during hazardous air quality days. Watch for coughing, lethargy, or difficulty breathing.

Conclusion

Monitoring air quality alerts in San Francisco is not merely a matter of convenience—it is a vital component of public health and personal safety in an era of increasing climate volatility. From wildfire smoke to urban ozone, the air we breathe is dynamic, often invisible, and always consequential. By understanding the AQI, leveraging reliable tools, and adapting daily habits, residents can significantly reduce their exposure and protect their long-term well-being.

This guide has provided a comprehensive, actionable roadmap—from setting up real-time alerts on your phone to installing air purifiers and advocating for cleaner policies. The most powerful tool you have is awareness. Make air quality a regular part of your daily routine, just like checking the weather or your calendar. In doing so, you’re not just protecting yourself—you’re contributing to a healthier, more resilient San Francisco for everyone.

Remember: Clean air is a right, not a privilege. Stay informed. Stay prepared. Breathe easier.