Air Quality Checker — Live AQI & Pollution Levels for Any City

The air can look clear and still be hard on your lungs. This free Air Quality Checker shows the live US AQI for any city on Earth, with a plain-language category — Good, Moderate, Unhealthy and beyond — plus the pollutants behind the number: fine particles PM2.5 and PM10, nitrogen dioxide, ozone and carbon monoxide. Check it before a run, a commute or a trip, and especially if you or your children live with asthma or allergies and need to plan the day around the air.

How the Air Quality Checker works

Type a city name and the tool first asks the Open-Meteo geocoding service to find matching places — pick yours from the list when several share a name. It then requests the current conditions for those exact coordinates from the Open-Meteo air quality service, which blends satellite data, ground stations and atmospheric models. The headline figure is the US Air Quality Index, shown with its category colour and a plain-language line about what it means for you. Underneath, a table lists the European AQI and each measured pollutant, and any value the model cannot provide is honestly shown as a dash rather than a guess.

How to use it

Search for your city, choose the right match from the picker, and read the big number first: that is the US AQI right now, at the time shown on the card. Let the category guide the decision — a run is fine on a Good day, worth shortening when the index is Unhealthy for sensitive groups, and better moved indoors when it is Very unhealthy or Hazardous. Then glance at the pollutant table to see why the air scores as it does: high PM2.5 points to smoke, traffic or dust particles, while high ozone is a sunny-afternoon problem.

Reading the AQI categories

The US scale runs from 0 to 500 in six bands. Good (0–50, green) means clean air for everyone. Moderate (51–100, yellow) is acceptable, though unusually sensitive people may notice symptoms. Unhealthy for sensitive groups (101–150, orange) is the point where children, older adults and people with heart or lung conditions should ease off heavy outdoor exercise. Unhealthy (151–200, red) affects the general public, Very unhealthy (201–300, purple) is a health alert, and Hazardous (301+, maroon) means emergency conditions — stay indoors where possible. The European index in the table uses its own scale, which is why the two numbers differ.

What the pollutants actually are

PM2.5 and PM10 are airborne particles measured in micrograms per cubic metre; PM2.5 is the finer and more dangerous of the two because it can pass deep into the lungs and bloodstream, and it usually drives the AQI on smoky or traffic-heavy days. Nitrogen dioxide (NO₂) comes mainly from vehicles and gas burning and irritates airways. Ground-level ozone (O₃) forms in sunlight from other pollutants and peaks on hot afternoons. Carbon monoxide (CO) comes from incomplete combustion. Knowing which one is high tells you the source — and whether opening a window helps or hurts.

Air Quality Checker – frequently asked questions

How current is the reading?

The card shows the model’s current conditions for your city and prints the exact time the reading refers to, in that city’s own timezone.

Why are the US and European AQI numbers different?

They are different scales built from the same air. Each index weights the pollutants and sets its band thresholds differently, so compare each number only against its own categories.

What should I do on an Unhealthy day?

Shorten outdoor exercise, keep reliever medication handy if you use it, close windows during the worst hours, and consider a well-fitting mask for essential trips outside.

Is the Air Quality Checker free?

Yes. It is completely free, needs no sign-up and no app, and you can check as many cities as you like.

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