Cities reporting air quality, Delhi

The number of cities in the geography that appear with an AQI in CPCB's daily AQI bulletin.

Methodology

Source: CPCB's daily National Air Quality Index bulletin. IHO counts the city rows in the bulletin's table that the crosswalk places in the geography; the India figure counts every row. Cities CPCB lists as absent for insufficient data are not counted. This is a coverage measure that qualifies the other three air-quality indicators, not a measure of air quality.

Caveats

A fall usually means stations were down or data were incomplete, not that monitoring was withdrawn. The bulletin printed only cities with continuous stations: about 10 in 2015, about 100 in 2020 and about 250–270 in 2024–26. Rows printed only as 'Aurangabad' from 18 July 2021 on cannot be placed in Bihar or Maharashtra; they count towards India only.

Comparability

Rises over time with network expansion; compare across years only as a description of coverage.

How signals are computed from this series: methodology.