Understanding Air Quality Index (AQI)¶

Learn how to interpret AirChain's air quality measurements.

What is AQI?¶

The Air Quality Index (AQI) is a standardized indicator of air pollution levels. AirChain uses the US EPA AQI scale, which ranges from 0 to 500.

AQI Categories¶

AQI Range	Category	Color	Health Implications
0-50	Good	🟢 Green	Air quality is satisfactory
51-100	Moderate	🟡 Yellow	Acceptable for most people
101-150	Unhealthy for Sensitive Groups	🟠 Orange	Sensitive individuals may experience issues
151-200	Unhealthy	🔴 Red	Everyone may begin to experience health effects
201-300	Very Unhealthy	🟣 Purple	Health alert - everyone may experience serious effects
301-500	Hazardous	🟤 Maroon	Emergency conditions - everyone affected

Health Recommendations by AQI¶

Good (0-50)¶

✅ Perfect for outdoor activities
✅ Open windows for ventilation
✅ No restrictions

Moderate (51-100)¶

✅ Generally safe for outdoor activities
⚠️ Unusually sensitive people should reduce prolonged outdoor exertion

Unhealthy for Sensitive Groups (101-150)¶

⚠️ Sensitive groups: reduce prolonged outdoor exertion
✅ General public can continue normal activities

Sensitive groups include: - Children - Elderly (65+) - People with asthma, heart disease, or lung disease - Pregnant women

Unhealthy (151-200)¶

🚫 Everyone: reduce prolonged outdoor exertion
🚫 Sensitive groups: avoid outdoor activities
💨 Keep windows closed
😷 Consider wearing N95 masks outdoors

Very Unhealthy (201-300)¶

🚫 Everyone: avoid all outdoor activities
🏠 Stay indoors with air purifiers if possible
😷 Wear N95 masks if must go outside
💨 Keep all windows closed

Hazardous (301-500)¶

🚨 Emergency conditions
🏠 Stay indoors at all times
😷 N95 masks required for any outdoor activity
🚑 Seek medical attention if experiencing symptoms

Lagos Context¶

Lagos frequently experiences AQI levels above 150 due to:

Traffic emissions: 10+ million vehicles
Generator exhaust: Unstable power grid
Industrial pollution: Manufacturing zones
Waste burning: Informal waste disposal
Dust: Harmattan season (Nov-March)

Annual deaths from air pollution in Lagos: ~11,200 people

Pollutants Measured¶

PM2.5 (Fine Particulate Matter)¶

Diameter: ≤2.5 micrometers
Sources: Vehicle exhaust, combustion
Health impact: Penetrates deep into lungs
Most harmful pollutant

PM10 (Coarse Particulate Matter)¶

Diameter: ≤10 micrometers
Sources: Dust, pollen, mold
Health impact: Irritates airways

CO2 (Carbon Dioxide)¶

Sources: Combustion, respiration
Health impact: High levels cause drowsiness

How AQI is Calculated¶

AirChain calculates AQI from PM2.5 and PM10 using the EPA formula:

AQI = max(AQI_PM2.5, AQI_PM10)

PM2.5 breakpoints (μg/m³): - Good: 0.0 - 12.0 - Moderate: 12.1 - 35.4 - USG: 35.5 - 55.4 - Unhealthy: 55.5 - 150.4 - Very Unhealthy: 150.5 - 250.4 - Hazardous: 250.5+

Real-Time Monitoring¶

Check current AQI in your area: - Dashboard: dashboard.airchain.ng - Mobile App: Download for Android/iOS - SMS: Text SUBSCRIBE to +234-XXX-XXXX

Long-Term Exposure Risks¶

Even moderate AQI (51-100) over months/years increases risk of: - Asthma development - Heart disease - Stroke - Lung cancer - Premature death