Air Quality Index Trends

AQI Scale

0-50 Good Air quality is satisfactory. No health concerns.

51-100 Moderate Acceptable for most. Unusually sensitive people may experience minor symptoms.

101-150 Unhealthy for Sensitive Groups Sensitive groups may experience health effects. General public less likely affected.

151-200 Unhealthy Everyone may experience health effects. Sensitive groups more serious effects.

201-300 Very Unhealthy Health alert: everyone may experience serious health effects.

301+ Hazardous Emergency conditions. Entire population likely affected.

Key Pollutants Measured

PM2.5: Fine particulate matter smaller than 2.5 micrometers. Primary contributor to reduced visibility and respiratory issues.
PM10: Inhalable particles 10 micrometers and smaller. Includes dust, pollen, and mold.
O₃ (Ozone): Ground-level ozone formed by chemical reactions between pollutants in sunlight. Peaks during afternoon hours.
NO₂: Nitrogen dioxide from vehicle emissions and power plants. Irritates airways and worsens respiratory diseases.
SO₂: Sulfur dioxide primarily from fossil fuel combustion. Can cause breathing difficulties within minutes of exposure.
CO: Carbon monoxide from incomplete combustion. Reduces oxygen delivery to organs and tissues.

Health Recommendations

Good (0-50): Perfect for outdoor activities. No precautions needed.

Moderate (51-100): Unusually sensitive individuals should consider reducing prolonged outdoor exertion.

USG (101-150): Children, elderly, and those with heart/lung conditions should limit prolonged outdoor exertion.

Unhealthy (151-200): Everyone should limit prolonged outdoor exertion. Sensitive groups avoid outdoor activity.

Very Unhealthy (201-300): Everyone should avoid outdoor exertion. Sensitive groups should remain indoors.

Hazardous (301+): Everyone should avoid all outdoor activity. Close windows and use air purifiers if available.

Factors Affecting Air Quality

Weather patterns: Wind speed, temperature inversions, and precipitation affect pollutant dispersion.
Traffic density: Rush hours typically show increased NO₂ and PM levels.
Industrial activity: Manufacturing and power generation contribute SO₂ and particulates.
Wildfires: Dramatically increase PM2.5 levels, sometimes affecting regions thousands of miles away.
Season: Summer increases ozone formation; winter often traps pollutants near ground level.
Geography: Valleys and bowls can trap pollutants; coastal areas benefit from ocean breezes.

Protecting Your Health

Indoor Air Quality

Use HEPA air purifiers in main living spaces
Keep windows closed on high AQI days
Replace HVAC filters regularly (MERV 13+ recommended)
Avoid burning candles or using fireplaces when outdoor AQI is elevated

Outdoor Precautions

Check AQI before planning outdoor activities
Exercise early morning when ozone levels are lower
Use N95 masks during very unhealthy conditions
Stay hydrated to help body process pollutants

High-Risk Groups

Children: Lungs still developing, breathe more air per body weight
Elderly: Weakened immune systems, pre-existing conditions
Asthma/COPD patients: Airways already compromised
Heart disease patients: Particulates strain cardiovascular system
Outdoor workers: Prolonged exposure increases health risks

Data Sources & Updates

Air quality data provided by the U.S. Environmental Protection Agency (EPA) through the AirNow program. Updates occur hourly from over 5,000 monitoring stations nationwide. The AQI calculation uses the highest value from all measured pollutants, ensuring public health protection based on the most significant threat.

Forecast models incorporate meteorological data, emission inventories, and satellite observations to predict AQI trends up to 5 days in advance. Accuracy typically exceeds 80% for next-day forecasts in urban areas.

7 million

Annual deaths worldwide attributed to air pollution (WHO)

91%

Of world population lives in areas exceeding WHO air quality guidelines

20%

Reduction in life expectancy in most polluted cities versus cleanest

$150 billion

Annual U.S. health costs from air pollution-related illness

Health