Delhi’s air improves slightly, recorded as ‘very poor’ after six consecutive days in ‘severe’ zone

The improvement from “severe” to “very poor” category was largely due to the wind speed gathering momentum and an appreciable dip in farm fire incidents in Punjab on Tuesday

The air quality index (AQI) of Delhi showed a marginal improvement on Wednesday morning after six consecutive days of pollution in the “severe” category.

The minimum temperature in the national capital recorded at 6.10am on Wednesday was 12 degrees Celsius. There was no fog, only mist. (Sanchit Khanna/HT Photo)

The AQI was in the “very poor” category as the early morning recording of 394 showed.

The improvement from “severe” to “very poor” category was largely due to the wind speed gathering momentum and an appreciable dip in farm fire incidents in Punjab on Tuesday.

An AQI between 401 and 500 and from 301 to 400 is considered in the “severe” and “very poor” category, respectively.

Poor AQI causes distress and respiratory illnesses, especially among the vulnerable population such as children and senior citizens, according to the Central Pollution Control Board (CPCB).

The minimum temperature in the national capital recorded at 6.10am on Wednesday was 12 degrees Celsius (C). There was no fog, only mist.

On Tuesday, at around 9:30 am, at least 18 stations in Delhi had reported an AQI of 500, which is the maximum on the pollution measurement metric.

A few private air quality monitoring platforms had even reported an AQI of 999, indicating that the pollution measuring values had hit the maximum level.

On Tuesday, the average 24-hour AQI in Delhi was 476, according to CPCB data. The past six days was one of the longest spells in the nation capital’s brush with “severe” air quality.

Scientists said that Wednesday’s improvement was primarily due to a change in wind speeds.

According to the Tuesday’s bulletin of System of Air Quality and Weather Forecasting and Research (SAFAR), a national initiative introduced by the Union Ministry of Earth Sciences (MoES), the wind condition further aggravated Delhi’s pollution woes.

The national capital is reeling under stubble burning in neighbouring Haryana, Punjab and also parts of western Uttar Pradesh (UP), which has become an annual feature around this time of the year.

“AQI is likely to improve on Wednesday. It will hover between the lower end of ‘severe’ and the higher end of ‘very poor’ category owing to a likely change in wind direction and marginally better ventillation condition,” the bulletin said.

“A few hundred farm fires were raging on Tuesday, as compared to thousands in the past week. Winds are also picking up. We are expecting an improvement in the pollution level,” said Vijay Soni, a scientist with India Meteorological Department (IMD).

The weather bureau has predicted that Wednesday would be foggy. The maximum and minimum temperature’s forecast is 30 and 11 degrees C, respectively.

On Tuesday, the minimum temperature had dropped to 10.7 degrees C -- three degrees below normal -- and maximum temperature stood at 30.1 degrees C – a notch above normal.