What will you discover?
Key takeaways
- PM2.5 stands for particulate matter measuring 2.5 micrometres or less across.
- A single particle is far too small for our eyes to see - what we see as smog is millions of them together.
- Most PM2.5 in Indian cities comes from vehicle exhaust, construction dust, industry and the burning of fuel or waste.
- Because the particles are so fine, they can pass deep into the lungs and enter the bloodstream.
- The AQI number on a weather app is largely a measure of how much PM2.5 is in the air right now.
Questions this video answers
What does PM2.5 mean?
PM stands for particulate matter and 2.5 is the size limit in micrometres. So PM2.5 means all the solid and liquid particles in the air that are 2.5 micrometres wide or smaller.
Can we see PM2.5?
Not one particle at a time - it is far too small for our eyes. We only notice PM2.5 when huge numbers of particles gather and the air turns hazy.
Where does PM2.5 come from?
Mostly from burning things: vehicle exhaust, factory smoke, cooking and heating fuel, crop and waste burning, and dust thrown up by construction and roads.
Why is PM2.5 harmful?
Larger dust is trapped in the nose and throat, but PM2.5 is small enough to reach deep into the lungs and even pass into the blood, which is why it affects breathing and health.
Take the learning further
Step outside with a notebook and spend ten minutes watching your street. Write down everything you can see that might be adding particles to the air - vehicles, a bonfire, a construction site, dust from the road. Then check the AQI for your city on a phone and see whether the number matches what you observed.
