In one line
PM₂.₅ and PM₁₀ are tiny dust particles in the air that can harm your lungs and health when you breathe them in.
Air pollution in India often contains high levels of PM₂.₅ and PM₁₀, especially after festivals or crop burning.
Image: Wikipedia
The rule
PM₂.₅ and PM₁₀ are types of particulate matter (tiny solid or liquid particles) in the air, named by their size: PM₂.₅ are particles smaller than 2.5 micrometres, and PM₁₀ are smaller than 10 micrometres.
- PM stands for Particulate Matter.
- The number (2.5 or 10) means the particle's diameter in micrometres (μm). 1 micrometre = 1/1,000,000 of a metre.
Let's understand it simply
Imagine you are riding your cycle on a busy Delhi road in winter. You see smoke from cars, dust from construction, and sometimes a thick haze. That haze is full of particulate matter — tiny pieces of dust, smoke, or soot floating in the air. PM₁₀ is like the bigger dust you see on your window sill after a day. PM₂.₅ is much, much smaller — so tiny you can't see it, but it can go deep into your lungs when you breathe.
Think of PM₁₀ as the size of flour particles, and PM₂.₅ as even finer than talcum powder. When you breathe, your nose hairs and throat can stop some big particles, but the very tiny ones (PM₂.₅) slip through and reach deep inside your lungs.
| PM₂.₅ | PM₁₀ | |
|---|---|---|
| Size | ≤ 2.5 μm | ≤ 10 μm |
| Can see with eyes? | No | Sometimes |
| Goes deep in lungs? | Yes | Mostly stays in nose/throat |
| Source | Smoke, exhaust, burning | Dust, construction, pollen |
| More harmful? | Yes | Less than PM₂.₅ |
How it works
- Sources: PM₁₀ and PM₂.₅ come from vehicles, burning garbage, factories, construction, and even cooking with wood or coal.
- Spread in air: These particles float in the air, especially when there is little wind or during winter.
- Breathing in: When you inhale, PM₁₀ can get trapped in your nose or throat, but PM₂.₅ can travel deep into your lungs.
- Health effects: PM₂.₅ can enter the smallest air sacs in your lungs and even pass into your blood.
- Body reaction: Your body tries to fight these particles, causing coughing, sneezing, or even serious lung and heart problems over time.
- Long-term harm: Breathing these particles every day can cause asthma, lung infections, heart disease, and even cancer.
- Particles float in air
- You breathe them in
- PM₁₀ gets trapped in nose/throat
- PM₂.₅ goes deep into lungs
- Body reacts (cough, illness)
The story behind it
Scientists started measuring air pollution in cities as people noticed more breathing problems and smog (thick air pollution). In the 1990s, researchers found that not just big dust, but very tiny particles (PM₂.₅) were causing serious health problems. They developed special machines to measure these particles. The World Health Organization (WHO) and governments now use PM₂.₅ and PM₁₀ levels to warn people about air quality.
One memorable detail: During the 2016 Diwali in Delhi, PM₂.₅ levels went so high that the air looked white and schools had to close.
Where you see it in real life
- Delhi smog: After Diwali, firecrackers release huge amounts of PM₂.₅ and PM₁₀, making the air hazy and hard to breathe.
- Busy roads: Auto rickshaws, buses, and trucks emit smoke full of PM₂.₅ and PM₁₀.
- Construction sites: Breaking bricks and mixing cement sends PM₁₀ dust into the air.
- Burning garbage: Open burning of waste releases both PM₂.₅ (from smoke) and PM₁₀ (from ash).
- Indoor cooking: Using wood or coal chulhas in villages fills the kitchen with PM₂.₅, making women and children cough.
- Crop burning: Farmers burning stubble in Punjab and Haryana send clouds of PM₂.₅ towards cities.
Why it matters
- Health: High PM₂.₅ and PM₁₀ cause asthma, lung infections, heart attacks, and can even shorten your life.
- Children and elderly: Kids, old people, and those with weak lungs suffer the most.
- Air quality index (AQI): PM₂.₅ and PM₁₀ are used to rate how safe the air is each day.
- Government action: Cities use PM₂.₅ and PM₁₀ data to decide when to ban firecrackers, stop construction, or close schools.
Worked example
Let's say the PM₂.₅ level in Delhi is 300 micrograms per cubic metre (μg/m³).
Given: PM₂.₅ = 300 μg/m³
Step 1: WHO safe limit for PM₂.₅ is 25 μg/m³ (24-hour average)
Step 2: Compare the value: 300 > 25
Step 3: Conclusion: The air is 12 times more polluted than the safe limit. It is dangerous to breathe without a mask.Common mistakes
- Thinking PM₂.₅ is just dust: PM₂.₅ is not just dust; it includes smoke, soot, and chemicals.
- Believing only outdoor air is polluted: Indoor air (from cooking or incense) can have high PM₂.₅ too.
- Assuming masks always help: Only special N95 masks can block PM₂.₅; cloth masks do not work well.
- Ignoring PM₂.₅ on clear days: Even if the sky looks blue, PM₂.₅ can still be high and harmful.
Remember it
PM₂.₅ is the invisible enemy in the air — small, sneaky, and dangerous for your lungs.
Check yourself
What does PM₂.₅ stand for?
Particulate matter with diameter less than or equal to 2.5 micrometres.
Why is PM₂.₅ more harmful than PM₁₀?
Because it is smaller and can go deep into your lungs, even entering your blood.
Name two common sources of PM₂.₅ in Indian cities.
Vehicle exhaust and burning garbage or crop stubble.
Why is wearing a cloth mask not enough to protect against PM₂.₅?
Because PM₂.₅ is so small that it passes through cloth; only N95 masks can block it.
Quick recap
- PM₂.₅ and PM₁₀ are tiny air particles; PM₂.₅ is smaller and more harmful.
- They come from vehicles, burning, construction, and even cooking.
- PM₂.₅ can go deep into your lungs and cause serious health problems.
- High levels are common in Indian cities, especially after festivals or crop burning.
- Only special masks (like N95) can block PM₂.₅ effectively.