Air Quality Index (AQI)

Air Quality Index (AQI) is a number that shows how clean or polluted the air is at a place and what it may mean for our health.

• What the number means: AQI usually runs from 0 to 500. A lower value means cleaner air; a higher value means more pollution and higher health risk.
• What it is based on: AQI is calculated using levels of common air pollutants such as PM2.5 and PM10 (tiny dust/smoke particles), ozone, nitrogen dioxide, sulphur dioxide, and carbon monoxide.
• Why PM2.5 matters a lot: PM2.5 particles are so small that they can go deep into the lungs and may even enter the blood, which is why they are strongly linked to coughing, asthma flare-ups, and breathing trouble.
• How to read AQI quickly (common bands): 0–50 Good, 51–100 Satisfactory, 101–200 Moderate, 201–300 Poor, 301–400 Very Poor, 401–500 Severe. As the band worsens, sensitive people (like children, older people, and asthma patients) are affected first.
• Everyday example: After crackers, heavy traffic, or crop burning, AQI can rise sharply—air may look hazy, eyes may sting, and breathing during sports can feel harder.
• Useful idea: AQI is about outdoor air at a location and time; it can change during the day with wind, rain, and traffic, so checking it helps you plan outdoor activity more safely.