AQI Full Form
Air Quality Index
What does AQI stand for? A science term, explained.
AQI Full Form in English, letter by letter
AQI is the Air Quality Index, a single number from 0 to 500 that tells you how clean or polluted the air is and what to do about it.
AQI Full Form in Indian Languages
Every winter, Delhi's AQI number becomes a public health warning. AQI, the Air Quality Index, is written here in six Indian languages.
What the Air Quality Index does
An Air Quality Index takes pollutant concentrations, measured in micrograms per cubic metre, and turns them into one number with a colour and a health message. The aim is to communicate. Few people change what they do because of 'PM2.5 at 118 µg/m³', but 'Moderate, sensitive people should reduce long outdoor exertion' is easy to act on.
India's National Air Quality Index was launched by the Central Pollution Control Board (CPCB) in 2014. It covers eight pollutants: PM2.5, PM10, ozone, nitrogen dioxide, carbon monoxide, sulphur dioxide, ammonia and lead. Each gets its own sub-index, and the AQI reported for a place is the highest of them, so one bad pollutant sets the whole day's number.
Reading the Indian AQI scale
The scale runs from 0 to 500 in six bands: Good (0 to 50), Satisfactory (51 to 100), Moderate (101 to 200), Poor (201 to 300), Very Poor (301 to 400) and Severe (401 to 500). Each band comes with a short advisory, from enjoying outdoor activity in the first band to staying indoors and avoiding exertion in the last.
Do not compare numbers across countries without checking the scale. The United States scale, for example, has different breakpoints and an extra band, Unhealthy for Sensitive Groups, that the Indian scale does not use. The same pollution level can therefore show a different AQI in two apps.
PM2.5 and PM10: the two particle readings
PM10 is coarse dust from roads, construction and burning. PM2.5 is much finer, mostly from combustion such as vehicles, industry, crop-residue burning and household fuel. Its particles are small enough to go deep into the lungs and enter the blood.
In winter, PM2.5 usually drives the AQI across the Indo-Gangetic plain, because cold air near the ground traps pollution (a temperature inversion) and wind is weak. In dry pre-monsoon months, dust can push PM10 up in Rajasthan and nearby states.
GRAP: what happens when the AQI crosses a line
In Delhi and the National Capital Region, the Commission for Air Quality Management enforces the Graded Response Action Plan. As the AQI worsens, tougher steps come in by stages: dust control at construction sites, limits on diesel generators, restrictions on trucks and older vehicles, and a halt to some construction and demolition work. Stricter stages can also bring changes to school and office arrangements.
Paddy-stubble burning in Punjab and Haryana adds to the region's pollution each October and November, and cold, still air keeps it close to the ground. SAFAR, run by the Indian Institute of Tropical Meteorology under the Ministry of Earth Sciences, has provided city-level air-quality forecasts.
Why the numbers matter for health
Fine particles are linked to asthma, heart disease, stroke and lung cancer. India's annual standard for PM2.5 is 40 µg/m³, while the WHO guideline value, revised in 2021, is 5 µg/m³. A day rated Satisfactory by Indian rules can still exceed what the WHO treats as safe.
Children, older people, pregnant women and people with asthma or heart disease should take readings in the Poor band and above seriously. Simple steps help: keep outdoor exercise for cleaner hours, wear a well-fitted N95 or equivalent mask on bad days, and keep indoor air free of smoke.
How AQI shows up in exams
The full form is a common SSC and UPSC question. Related facts worth learning: the six bands, the eight pollutants, that the highest sub-index is reported, and that the CPCB works under the Ministry of Environment, Forest and Climate Change.
UPSC mains has asked about air pollution and policy response more than once, usually framed around the Indo-Gangetic plain in winter and crop-residue burning.
AQI is one of the few acronyms that can change your day: a reading in the Very Poor band is a good reason to skip the morning walk. Know the six bands and check your own city's number.
AQI Full Form: Common Questions
What is the full form of AQI?
Air Quality Index. It converts pollutant concentrations into a single number with a colour code and health advice, showing how polluted the air is.
What are the six AQI categories in India?
Good (0 to 50), Satisfactory (51 to 100), Moderate (101 to 200), Poor (201 to 300), Very Poor (301 to 400) and Severe (401 to 500).
Which pollutants does India's AQI measure?
PM2.5, PM10, ozone, nitrogen dioxide, carbon monoxide, sulphur dioxide, ammonia and lead. The AQI shown for a place is the highest sub-index among those measured.
What is GRAP and when does it apply?
The Graded Response Action Plan, enforced by the Commission for Air Quality Management in the NCR. It brings in tougher pollution-control steps in stages as the AQI worsens.
Why do two apps show different AQI for my city?
They may use different monitoring stations, different time averages or a different scale, such as the US scale instead of the Indian one. Check which station and scale the app is showing.
Is AQI asked in Indian competitive exams?
Yes. The full form, the six bands, the eight pollutants and the CPCB's role recur in SSC, UPSC and state-level environment sections.