Delhi on Friday saw the cleanest air quality of the year after witnessing record rainfall in September. The national capital recorded an Air Quality Index (AQI) of 52, teetering on the edge of "good" and "satisfactory" AQI classifications.

Faridabad recorded a 24-hour average AQI of 24. Ghaziabad and Noida followed closely, registering AQIs of 34 and 46, respectively, all falling within the "good" category.

Meanwhile, Gurugram recorded an AQI of 69, Bulandshahr clocked an AQI of 21, Meerut posted a 28, and Muzaffarnagar recorded an AQI of 29.

This significant improvement can be attributed to a combination of depression activity and the active monsoon trough, which brought substantial rainfall to the entire Delhi NCR region.

The rain effectively washed away pollutants, while the accompanying wind speeds of 30-40 kmph helped disperse residual contaminants.

Delhi also exceeded its annual and seasonal average rainfall in the early days of September, with total rainfall crossing the 1,000 mm mark.

Delhi recorded 54 mm of rainfall in Palam, while the weather station at Safdarjung recorded 30.9 mm of rainfall within three hours on Friday, from 2.30 to 5.30 pm, PTI reported.

Delhi has also surpassed its monthly average rainfall, with 125.8 mm recorded in September, 55% higher than normal, according to official data.

September 2023 saw below-average rainfall, with only 82.7 mm recorded, 33% lower than the normal amount.

Rainfall measuring between 64.5 mm and 115.5 mm is considered "heavy", between 115.6 mm and 204.4 mm "very heavy", and above 204.5 mm "extremely heavy".

The AQI scale ranges from "good" (0-50) to "severe" (401-500), with "satisfactory" (51-100) indicating that air quality poses little or no risk.

Source: India Today