US Air Quality Index 2026: Live AQI for Every City
Check air quality NOW before going outside. Real-time AQI, PM2.5, ozone levels & 5-day forecasts. Is it safe to run, walk, or exercise? Find out in seconds.
Your Source for Real-Time Air Quality Data
US Air Quality provides comprehensive, up-to-date air quality information for cities across the United States. Understanding the air you breathe is essential for protecting your health and planning outdoor activities. Our platform makes it easy to check current conditions, compare cities, and understand what air quality levels mean for you and your family.
Air pollution can trigger asthma attacks, worsen respiratory conditions, and pose serious health risks for sensitive groups including children, elderly individuals, and those with heart or lung disease. By monitoring the Air Quality Index (AQI) in your area, you can make informed decisions about when to exercise outdoors, keep windows open, or take extra precautions to protect your health.
How to Use This Site
- Search for your city to see current AQI and forecasts
- Compare air quality between cities before traveling or moving
- Check seasonal patterns and wildfire smoke impacts
- Use our calculators to plan safe outdoor activities
Our Data Sources
Air quality measurements come from the EPA's AirNow program, which collects real-time data from thousands of monitoring stations operated by state, local, and tribal agencies nationwide. This official government data is updated hourly for accurate, reliable AQI readings.
Note: AQI values shown on this site are estimates based on historical averages and seasonal patterns. For real-time air quality data, visit AirNow.gov.
Understanding the Air Quality Index
The AQI tells you how clean or polluted your air is, and what health effects might be a concern.
Best Air Quality Today
Cities with the cleanest air
Poorest Air Quality Today
Cities requiring caution
Explore Air Quality Data
Dive deeper into air quality trends, rankings, and health information
Cleanest Cities
Top 50 US cities with the best air quality and healthiest living conditions
Most Polluted Cities
Cities with elevated pollution levels requiring health precautions
Cities by State
Browse all monitored cities organized by state with AQI data
Active AQI Alerts
Real-time air quality alerts and health advisories for your area
Health Guide
Protection strategies and health information for sensitive groups
Complete Rankings
Full rankings of all cities from best to worst air quality
Health Calculators
Calculate safe outdoor time, health risks, and mask requirements
Seasonal Patterns
Month-by-month AQI trends, wildfire season, inversions, and travel planning
Activity Guides
Air quality guidelines for running, cycling, hiking, sports, and 10+ more activities
Browse by State
Good (0-50)
Unlimited outdoor activity is safe for everyone
Moderate (51-100)
Normal outdoor activity for most people; sensitive individuals should watch for symptoms
Unhealthy for Sensitive Groups (101-150)
General public can be active but should take breaks; sensitive groups should limit outdoor exertion
Unhealthy (151-200)
Everyone should avoid prolonged outdoor exertion; sensitive groups should stay indoors
Very Unhealthy (201-300)
Everyone should avoid all outdoor exertion; stay indoors
Hazardous (301-500)
No outdoor activity for anyone - emergency conditions
Our Data Sources
We aggregate official government data to make air quality information accessible.
EPA AirNow
Real-time air quality data from the official EPA monitoring network covering 2,000+ stations nationwide.
EPA Air Quality System (AQS)
Historical air quality data and long-term trends from the EPA official repository.
National Ambient Air Quality Standards
EPA standards that define acceptable pollutant concentrations for public health protection.
EPA Health Guidelines
Official health recommendations and AQI guidance from the Environmental Protection Agency.
Note: We do not create or modify air quality measurements. All data is sourced directly from official EPA monitoring systems and presented without alteration. For the most authoritative real-time data, visit AirNow.gov.
Frequently Asked Questions About Air Quality
The Air Quality Index (AQI) is the EPA's standardized scale for measuring air pollution levels. It ranges from 0 to 500, where 0-50 is good (green), 51-100 is moderate (yellow), 101-150 is unhealthy for sensitive groups (orange), 151-200 is unhealthy (red), 201-300 is very unhealthy (purple), and 301-500 is hazardous (maroon). The AQI considers five major pollutants: ground-level ozone, particle pollution (PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide.
Have more questions about air quality?
What is the Air Quality Index?
The Air Quality Index (AQI) is the EPA's standardized system for communicating how clean or polluted the air is in your area. Developed by the Environmental Protection Agency, the AQI translates complex air quality measurements into a simple scale from 0 to 500, where lower numbers indicate cleaner air and higher numbers indicate more pollution. The AQI focuses on health effects you may experience within a few hours or days after breathing polluted air.
The AQI is calculated for five major air pollutants regulated by the Clean Air Act: ground-level ozone, particle pollution (PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide. The highest AQI value among these pollutants becomes the reported AQI for that location and time period.
Who is Most at Risk?
While poor air quality affects everyone, certain groups are more sensitive to air pollution and should take extra precautions when AQI levels rise:
- People with asthma, COPD, or other respiratory conditions
- Children and older adults (65+)
- People who work or exercise outdoors regularly
- People with heart disease or cardiovascular conditions
- Pregnant women and developing fetuses
- People with diabetes or compromised immune systems
How to Protect Yourself
Taking simple precautions on poor air quality days can significantly reduce your exposure to harmful pollutants and protect your health:
- Check the AQI before planning outdoor activities, especially exercise
- Limit prolonged outdoor exertion when AQI is unhealthy (above 100)
- Keep windows and doors closed on poor air quality days
- Use air purifiers with HEPA filters to improve indoor air quality
- Run your car's air conditioning on recirculate mode when driving
- Wear N95 or KN95 masks during very poor air quality (AQI above 150)
- Create a clean air room in your home for severe pollution events
Data Accuracy and Updates
All air quality data displayed on US Air Quality comes from the EPA's official AirNow system, which aggregates real-time measurements from state, local, and tribal air monitoring agencies across the United States. Monitoring stations measure pollutant concentrations continuously, and data is typically updated hourly. While we strive to display the most current information, actual conditions may vary based on local factors and time since last measurement update.