Air Quality Index Calculator

Calculate and understand the Air Quality Index (AQI) based on pollutant concentrations. Assess health risks and recommendations.

Fine particulate matter, diameter ≤ 2.5μm
Coarse particulate matter, diameter ≤ 10μm
8-hour average concentration
1-hour average concentration
1-hour average concentration
8-hour average concentration
Calculating AQI...

Understanding the Air Quality Index (AQI)

The Air Quality Index (AQI) is a standardized system used to communicate how polluted the air currently is or how polluted it is forecast to become. The AQI scale ranges from 0 to 500, with higher values indicating worse air quality and greater health concerns.

Key Insight: 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.

AQI Categories and Health Implications

1

Good (0-50): Air quality is satisfactory, and air pollution poses little or no risk.

2

Moderate (51-100): Air quality is acceptable. However, there may be a risk for some people, particularly those who are unusually sensitive to air pollution.

3

Unhealthy for Sensitive Groups (101-150): Members of sensitive groups may experience health effects. The general public is less likely to be affected.

4

Unhealthy (151-200): Some members of the general public may experience health effects; members of sensitive groups may experience more serious health effects.

5

Very Unhealthy (201-300): Health alert: The risk of health effects is increased for everyone.

6

Hazardous (301-500): Health warning of emergency conditions: everyone is more likely to be affected.

Major Air Pollutants

  • Particulate Matter (PM2.5 and PM10): Microscopic solids or liquid droplets that can be inhaled and cause serious health problems
  • Ozone (O3): A gas that occurs both in the Earth's upper atmosphere and at ground level, where it's a harmful air pollutant
  • Nitrogen Dioxide (NO2): A reddish-brown gas with a sharp, biting odor, primarily emitted from vehicles and industrial facilities
  • Sulfur Dioxide (SO2): A gas that is invisible and has a sharp, pungent smell, primarily produced from burning fossil fuels
  • Carbon Monoxide (CO): A colorless, odorless gas that can be harmful when inhaled in large amounts

AQI Scale Comparison

AQI Category AQI Range Health Concern Level Color
Good 0-50 Minimal impact Green
Moderate 51-100 Acceptable Yellow
Unhealthy for Sensitive Groups 101-150 Moderate health concern Orange
Unhealthy 151-200 Health effects possible Red
Very Unhealthy 201-300 Health alert Purple
Hazardous 301-500 Health warning Maroon

How to Protect Yourself from Poor Air Quality

When air quality is poor:

  • Check daily AQI forecasts: Stay informed about local air quality conditions
  • Limit outdoor activities: Especially during high pollution periods
  • Use air purifiers: Especially important for indoor air quality
  • Wear masks: N95 or similar masks can help filter out particulate matter
  • Keep windows closed: During high pollution days to prevent outdoor air from entering
  • Use public transportation: Reduce personal vehicle use to help improve air quality

Health Impact: Poor air quality can aggravate respiratory diseases like asthma, increase risk of heart attacks, and contribute to premature death in people with heart or lung disease. Children, older adults, and people with pre-existing conditions are especially vulnerable.

Frequently Asked Questions

PM2.5 refers to fine inhalable particles with diameters that are generally 2.5 micrometers and smaller. PM10 refers to inhalable particles with diameters that are generally 10 micrometers and smaller. PM2.5 particles are more dangerous because they can travel deeper into the respiratory system and even enter the bloodstream.

AQI values are typically updated hourly for real-time monitoring. Some locations may update less frequently depending on the availability of monitoring equipment and data.

Yes, AQI can vary significantly within the same city due to local pollution sources, topography, weather conditions, and distance from monitoring stations. Industrial areas, busy roads, and valleys where pollution can accumulate often have higher AQI values.

Air quality is often worst during rush hours (morning and evening) due to increased vehicle emissions. Ozone levels typically peak in the afternoon when sunlight reacts with pollutants. In winter, particulate matter can be higher in the morning due to temperature inversions that trap pollution near the ground.

Personal air quality monitors vary in accuracy. Higher-end models can be quite accurate for particulate matter measurements, but may be less reliable for gas measurements. They're best used for relative comparisons (better/worse) rather than absolute measurements, and should be calibrated periodically for best results.