Understanding the Air Quality Index in 2026

The Air Quality Index (AQI) is a standardized system used to communicate the quality of air in a specific area, indicating potential health risks associated with air pollution. In 2026, understanding the AQI remains crucial for public health and safety.

What Is the Air Quality Index (AQI)?

The AQI is a numerical scale ranging from 0 to 500, divided into six color-coded categories that represent increasing levels of health concern:

• 0 to 50 (Green): Good. Air quality is satisfactory, posing little or no risk.
• 51 to 100 (Yellow): Moderate. Air quality is acceptable; however, some pollutants may be a concern for a small number of individuals sensitive to air pollution.
• 101 to 150 (Orange): Unhealthy for Sensitive Groups. Members of sensitive groups may experience health effects.
• 151 to 200 (Red): Unhealthy. Everyone may begin to experience health effects; members of sensitive groups may experience more serious effects.
• 201 to 300 (Purple): Very Unhealthy. Health alert: everyone may experience more serious health effects.
• 301 to 500 (Maroon): Hazardous. Health warning of emergency conditions; the entire population is more likely to be affected.

These categories help individuals understand the potential health impacts of air pollution levels in their area. (epa.gov)

How Is the AQI Calculated?

The AQI is calculated based on the concentrations of specific air pollutants that have known health effects. In the United States, the primary pollutants include:

• Ground-level ozone (O₃): A major component of smog, formed when sunlight reacts with pollutants from vehicles and industrial emissions.
• Particulate matter (PM₂.₅ and PM₁₀): Tiny particles or droplets in the air that can penetrate deep into the lungs and even enter the bloodstream.
• Carbon monoxide (CO): A colorless, odorless gas produced by burning fossil fuels.
• Sulfur dioxide (SO₂): A gas produced by burning fossil fuels and industrial processes.
• Nitrogen dioxide (NO₂): A gas produced by burning fuel, especially in vehicles and power plants.

Each pollutant has its own AQI scale, and the highest individual AQI value among these pollutants determines the overall AQI for the area. (epa.gov)

Health Implications of Different AQI Levels

Understanding the health implications associated with various AQI levels is essential:

• 0 to 50 (Good): Air quality is satisfactory, posing little or no risk.
• 51 to 100 (Moderate): Air quality is acceptable; however, some pollutants may be a concern for a small number of individuals sensitive to air pollution.
• 101 to 150 (Unhealthy for Sensitive Groups): Members of sensitive groups may experience health effects.
• 151 to 200 (Unhealthy): Everyone may begin to experience health effects; members of sensitive groups may experience more serious effects.
• 201 to 300 (Very Unhealthy): Health alert: everyone may experience more serious health effects.
• 301 to 500 (Hazardous): Health warning of emergency conditions; the entire population is more likely to be affected.

These categories help individuals understand the potential health impacts of air pollution levels in their area. (epa.gov)

How to Monitor Air Quality Effectively

Monitoring air quality is vital for making informed decisions about outdoor activities and health precautions. Here are some effective ways to stay informed:

• Use Official Resources: The Environmental Protection Agency (EPA) provides real-time AQI information on their website and through the AirNow app.
• Check Local Forecasts: Many local weather services include AQI information in their daily forecasts.
• Stay Informed During Events: During events like wildfires or industrial accidents, AQI levels can change rapidly. Stay updated through official channels.

By staying informed about the AQI, individuals can take appropriate actions to protect their health and well-being.

Understanding the AQI and its implications empowers individuals to make informed decisions about their health and outdoor activities, ensuring safety and well-being in varying air quality conditions.

Highlights:

• About Air Quality | Air Quality | CDC, Published on Sunday, May 03
• Communicating Air Quality Conditions: The Air Quality Index | US EPA, Published on Monday, September 29
• Indoor Air Quality (IAQ) Frequently Asked Questions | US EPA, Published on Wednesday, July 23