After light rain, Delhi sees November’s first ‘moderate’ air day

Delhi’s AQI Wednesday was 134 — a significant improvement from 270 the previous day, as per the Central Pollution Control Board (CPCB). Among the NCR towns, the AQI of Gurgaon was 104, Noida’s was 115 and Ghaziabad’s was 143.

Weather and air quality experts have credited this improvement in air to a reduction of stubble burning in Haryana and Punjab, coupled with favourable meteorological conditions.

“Under the influence of the Western Disturbance, precipitation recorded in Delhi and its North Western regions has led to washing out of suspended pollutants and rapid improvement in air quality,” said a report by the Centre’s weather and air monitoring agency SAFAR.

Kuldeep Srivastava, a scientist at the India Meteorological Department (IMD), said showers under the WD were recorded in parts of Haryana Tuesday and Wednesday, as a result of which farm fires and their emissions have reduced.

Delhi’s air quality has improved significantly in the past week.

SAFAR estimated that stubble burning contributed 2% to PM2.5 levels in Delhi Wednesday, which is expected to increase to 4% Thursday. It has also recorded a declining trend in farm fires.

Wind direction over Delhi is Northwesterly, which is favourable for transport of stubble burning emissions, but light surface winds expected over the next few days would keep pushing pollutants out, Srivastava said.

The windspeed peaked around 15 km per hour Wednesday and is expected to reduce to around 8 km per hour Thursday, the IMD official said.

Rainfall was recorded more in the city’s north Wednesday as compared to the south, Srivastava said, but it remained in the light to drizzle range.

A CPCB official said rain helps settle dust and other particulates that are suspended in the air and increases the duration between their re-suspension.

Real time air quality at 28 out of 31 monitoring stations in Delhi as of 8 pm Wednesday was in the ‘moderate’ category, with the remaining three stations — Najafgarh, Vivek Vihar and Sonia Vihar — recording AQI in the ‘satisfactory’ range.

As per a SAFAR forecast, the capital’s air quality will likely remain in the ‘moderate’ category Thursday and may deteriorate to the ‘poor’ range by Friday.