Air quality index (mean of reporting cities), Assam | India Health Observatory

Air quality index (mean of reporting cities), Assam

Name: Air quality index (mean of reporting cities), Assam
Creator: Central Pollution Control Board, Ministry of Environment, Forest and Climate Change
License: https://data.gov.in/government-open-data-license-india

The unweighted mean of the National Air Quality Index (AQI) of every city in the geography that appears in CPCB's daily AQI bulletin, for the 24 hours ending 16:00 IST. Lower is better: 0–50 Good, 51–100 Satisfactory, 101–200 Moderate, 201–300 Poor, 301–400 Very Poor, 401–500 Severe.

66AQI

3 October 2026

+8 (+13%) from 59 AQI in 2 October 2026. A move in the worse direction.

Derived figure

Published in: CPCB National Air Quality Index bulletin, 3 October 2026 (252 cities)
Where in the document: AQI bulletin p.3–12, Index Value column: mean of 5 city rows placed in Assam — Byrnihat (Assam) (p.3), Guwahati (p.5), Nagaon (p.9), Silchar (p.11), Sivasagar (p.12)
Evidence: Archived file Original URL Method
First seen by the observatory: 3 Oct 2026. Fetched directly from the publisher.

AssamIndia

100

150

200

Where Assam stands

3 October 2026. 30 reporting

All reporting states for 3 October 2026, highest first.

050100150200

India

103

Delhi

171

Tripura

Signals

All signals

What the observatory's code found notable in this series.

−20%Improving

14 September 2026Outside the usual rangeAssam

Assam: average air quality index over the 7 days to 14 September 2026 was 58, below the 5-year median of 72 for the same week (−20%).

CPCB air quality Original document Method Data

History

Download CSV

Every value, newest first. Each figure opens the release it was read from.

Period	Assam	India	Status	Where in the document
3 October 2026	66	103	Derived	AQI bulletin p.3–12, Index Value column: mean of 5 city rows placed in Assam — Byrnihat (Assam) (p.3), Guwahati (p.5), Nagaon (p.9), Silchar (p.11), Sivasagar (p.12)
2 October 2026	59	103	Derived	AQI bulletin p.3–12, Index Value column: mean of 6 city rows placed in Assam — Byrnihat (Assam) (p.3), Guwahati (p.5), Nagaon (p.9), Nalbari (p.9), Silchar (p.11), Sivasagar (p.12)
1 October 2026	58	98	Derived	AQI bulletin p.3–11, Index Value column: mean of 6 city rows placed in Assam — Byrnihat (Assam) (p.3), Guwahati (p.5), Nagaon (p.9), Nalbari (p.9), Silchar (p.11), Sivasagar (p.11)
30 September 2026	64	90	Derived	AQI bulletin p.3–12, Index Value column: mean of 6 city rows placed in Assam — Byrnihat (Assam) (p.3), Guwahati (p.6), Nagaon (p.9), Nalbari (p.9), Silchar (p.12), Sivasagar (p.12)

Definition and method

Numerator: Sum of the Index Values of the reporting cities
Denominator: Number of reporting cities

Methodology

Source: CPCB's daily National Air Quality Index bulletin, published about 16:05 IST for the 24 hours ending 16:00 IST. Each city row's Index Value is CPCB's National AQI (0–500): for every participating continuous monitoring station CPCB computes a sub-index for each pollutant measured (PM2.5, PM10, NO2, SO2, CO, O3, NH3, Pb; at least three, one of them PM2.5 or PM10), takes the highest sub-index as the station AQI, and reports the arithmetic mean of the city's station AQIs. CPCB itself notes that averaging across locations 'is not a scientifically sound approach' and is done for simplicity. IHO takes every city row in the bulletin, assigns it to a state with a curated city-to-state crosswalk (built from CPCB's station list and Delhi-NCR bulletin, and from the bulletin's own state labels such as 'Aurangabad (Maharashtra)'), and reports the arithmetic mean of the Index Values of the cities in each state, each city counting once whatever its population or number of stations. The India figure is the mean over all reporting cities in the bulletin, not the mean of the state figures, so states with many monitored cities weigh more. A city name the crosswalk does not know stops the release rather than being dropped. From 18 July 2021, when Bihar's Aurangabad station could have joined the bulletin, a row printed only as 'Aurangabad' may be Bihar's or Maharashtra's (on 34 days in 2022 the bulletin printed two such rows); those rows count towards India but towards neither state.

Caveats

This is a summary convention, not an exposure measure: it is not population-weighted, a mean of AQIs is not the AQI of mean concentrations (each AQI is the worst pollutant's sub-index, and the worst pollutant differs between cities), and it says nothing about rural air. A state figure based on one city is just that city's AQI; such values are marked low-sample. Coverage is urban and uneven: only cities with continuous monitoring stations appear, the network is concentrated in the Indo-Gangetic plain, Maharashtra, Rajasthan, Karnataka and Haryana, and several states and union territories have one city or none on a given day. Cities with insufficient data drop out of a day's bulletin and come back, so the set of cities behind a state's figure changes from day to day. The network grew from about 10 cities in May 2015 to about 100 in 2020 and about 250–270 in 2024–26, so long-run comparisons, especially for India as a whole, partly reflect which cities were added (many smaller towns from 2021 onward) rather than a change in the air. A city's Index Value is the 24-hour average to 16:00 IST over whichever of its stations reported that day; some bulletins mark stations whose data ended at 15:00.

Revisions

Government figures are revised. Earlier values are kept, never silently overwritten.

No value in this series has been revised since the observatory first archived it.

Source releases

The government publications this series was read from.

CPCB National Air Quality Index bulletin, 15 November 2023 (248 cities)PublishedSeen 3 Oct 2026File
CPCB National Air Quality Index bulletin, 10 April 2021 (124 cities)PublishedSeen 3 Oct 2026File
CPCB National Air Quality Index bulletin, 12 April 2021 (125 cities)PublishedSeen 3 Oct 2026File
CPCB National Air Quality Index bulletin, 11 April 2021 (126 cities)PublishedSeen 3 Oct 2026File
CPCB National Air Quality Index bulletin, 13 April 2021 (123 cities)PublishedSeen 3 Oct 2026File
CPCB National Air Quality Index bulletin, 15 April 2021 (126 cities)PublishedSeen 3 Oct 2026

Cite this

India Health Observatory (2026). Air quality index (mean of reporting cities), Assam, 10 April 2021 to 3 October 2026 [dataset]. Original data: Central Pollution Control Board, Ministry of Environment, Forest and Climate Change, CPCB air quality. https://indiahealthobservatory.com/india/assam/air-quality-index

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