What is AQI? PM2.5 vs PM10 explained for families

Authorities track multiple pollutants, like smoke particles, dust, and gases, and whichever pollutant is at the worst level usually decides the AQI number you see.

What is AQI: When winter sets in, the air in many cities starts to look hazy; a mixture of fog, smoke, and dust that won’t lift. That’s when terms like AQI, PM2.5, and PM10 pop up everywhere: news tickers, weather apps, school WhatsApp groups. But beyond the buzzwords, these numbers matter because they tell you how safe the air is for your lungs, especially for kids, older adults, and anyone with asthma or allergies.

So, what exactly is AQI?

AQI stands for Air Quality Index. It’s a single score that sums up how polluted the air is on a given day and what that pollution could mean for your health. Think of it as a quick “air safety rating.” Authorities track multiple pollutants, like smoke particles, dust, and gases, and whichever pollutant is at the worst level usually decides the AQI number you see.

Also Read | Early COPD symptoms you shouldn’t ignore

AQI levels and what they mean for your health

AQI Range	Air Quality	What it can mean for health
0-50	Good Air	It is generally safe for everyone
51-100	Satisfactory	Usually okay; very sensitive people may feel mild irritation.
101–200	Moderate	Some may notice mild throat discomfort, breathing irritation.
201–300	Poor	Kids, elderly, and people with asthma/allergies may feel symptoms sooner.
301–400	Very poor	Higher risk for everyone; outdoor activity should be limited.
401–500	Severe	Hazardous air; even healthy people can feel unwell. Avoid the outdoors.

What are PM2.5 and PM10?

You’ll often see PM2.5 and PM10 listed alongside AQI. PM stands for particulate matter; tiny solid and liquid particles floating in the air. The number tells you the particle size in micrometres (µm).

PM10 = larger particles (up to 10 µm)

These are the dustier, heavier particles, about one-seventh the width of a human hair. They usually get trapped in the nose, throat, and upper airways.

Common sources:

Road dust
Construction and demolition work
Burning leaves/wood
Vehicle emissions

What it can do to the body:

Throat irritation, coughing
Triggered asthma symptoms
Shortness of breath, especially during exertion

Pollution often peaks in early mornings and evenings, so those are good times to double-check before stepping out.

PM2.5 = ultra-fine particles (2.5 µm or smaller)

These are much smaller, roughly 30 times thinner than a human hair. Because they’re so fine, they can travel deep into the lungs and may even enter the bloodstream, which is why they’re considered more harmful.

Common sources:

Diesel and vehicle exhaust
Factory and industrial emissions
Crop-residue burning
Fireworks and cigarette smoke

What it can do to the body:

Burning eyes, irritated throat
Cough, phlegm, breathing trouble
Higher long-term risk for heart and lung disease
More infections and weaker immunity in children

How AQI and PM levels affect your day:

AQI Category	What you may notice	What to do
Good (0–50)	Clear air, easy breathing	Outdoor walks and play are fine.
Moderate (51–100)	Mild haze	Sensitive people should limit dusty exposure.
Poor (101–200)	Visible smog, mild irritation	Reduce outdoor time for kids/elderly.
Very Poor (201–300)	Eye burn, strong smell	Use masks outdoors; consider purifier indoors.
Severe (300+)	Thick smog, breathlessness	Stay indoors as much as possible.

How to check AQI in your area

It’s quick: check your phone’s weather app, local air-quality apps, or official sources like the Central Pollution Control Board (CPCB). Pollution often peaks in early mornings and evenings, so those are good times to double-check before stepping out.

How to protect yourself from bad AQI?

If AQI is above 200, cut outdoor time and avoid outdoor workouts
Keep windows shut during peak pollution hours
Use an air purifier if possible, especially for PM2.5-heavy days
Indoor plants can improve the feel of indoor air, but they won’t replace ventilation or purification

Also Read | Why air pollution worsens asthma, and what you can control

Air pollution isn’t just a “science topic”; it shows up in your throat, your eyes, and your breathing. So, along with temperature and rain, make AQI part of your daily weather check.