Clean Air Challenge: Read the AQI, Fix the Air
See air quality as a balance: sources add fine particles, wind and rain remove them, and a winter inversion traps the same emissions in a shallow layer so concentrations soar.
Before you try
What if the wind stopped for a week in November? How high could the AQI go?
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What happened?
Move a control to see what changes and why.
One well-mixed box over the city with rounded emission and removal rates; real air also depends on pollution blown in and chemistry in the air.
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Try these ideas
- Load the Delhi November preset and watch the AQI climb. Then switch the inversion off.
- Keep every source the same and raise the wind from 0 to 20 km/h.
- Find the biggest single source in the model by zeroing them one at a time.
Why it works
PM2.5 means particles smaller than 2.5 micrometres, thirty times thinner than a hair, small enough to reach deep into the lungs and blood. They come from vehicle exhaust, factories and power plants, burning crop stubble and rubbish, and dust from roads and building sites. India’s safe daily limit is 60 µg/m³; Delhi winter days often pass 300, and the Air Quality Index turns those numbers into bands from Good to Severe.
Why winter is worst: cold, still air settles under a layer of warmer air, an inversion that acts like a lid, and the same smoke is squeezed into a shallow layer. Wind and rain are the cleaners; when they stop, only cutting emissions works. In this challenge you set each source, the weather and the inversion, run the hours, and read the PM2.5 and AQI band.
Check your understanding
Question 1 of 4
PM2.5 is
Air pollution in north India peaks in winter because
Which weather cleans the air fastest?
The Indian AQI band for PM2.5 of 40 µg/m³ is
Explain it in your own words
What changed? Why did it happen? Where might you notice this in everyday life?
For parents & teachers
- Check today’s AQI for your city on the CPCB site and name the band.
- Ask: why do masks with fine filters help but ordinary cloth does not?
- List the sources of smoke you can see on your street.