Pollution in Delhi creeps back to ‘very poor’, temperature stays low

Temperatures continued to remain low in Delhi, with the mercury at 6.6 degrees Celsius on Monday morning at Safdarjung, Delhi’s base observatory. While this was two degrees below normal, the city recorded a maximum temperature of 22.4°C, a notch below normal.

Delhi recorded this season’s lowest minimum temperature — 6.4°C — a day earlier,

The cooler days and nights did, however, adversely affect pollution levels, pushing the air quality index (AQI) into the ‘very poor’ zone.

Delhi recorded this season’s lowest minimum temperature — 6.4°C — a day earlier, and the India Meteorological Department (IMD) said the city can expect a similar chill for the rest of the week.

RK Jenamani, scientist at IMD, said the minimum temperature will hover between 6°C and 8°C till the end of the week, with two western disturbances in the northern plains likely to marginally influence Delhi.

“These are feeble western disturbances, so the impact will not be too significant. The minimum temperature may rise to 8°C, but a drop in mercury is expected from December 17,” said Jenamani.

At 6.6°C, Safdarjung in south Delhi was the coldest spot in the national capital on Monday morning, while Mayur Vihar in east Delhi recorded the city’s lowest maximum at 20.8°C.

The IMD’s forecast for Tuesday showed that the maximum temperature is likely to hover around 23°C, while the minimum is likely to remain around the 6°C mark.

The drop in temperatures, particularly at night and in the early hours of the day has also pushed Delhi’s air quality back into the ‘very poor’ category, with a 24-hour average AQI of 331 at 4pm, according to the Central Pollution Control Board. In comparison, it was 254 (poor) on Sunday.

Experts said wind speeds are again expected to pick up from December 15.

“The AQI will hover between ‘poor’ and ‘very poor’ during this period. Low temperatures are unfavourable for the dispersal of pollutants, but an increase in wind speeds from December 15 may once again bring down the AQI to ‘poor’,” said Gufran Beig, founder and project director, System of Air Quality and Weather Forecasting And Research (Safar) — a forecasting body under the Union ministry of earth sciences.

The Early Warning System (EWS) for Delhi, which also falls under the ministry of earth sciences, also forecasts Delhi’s air quality to hover between ‘poor’ and ‘very poor’ during the next seven days, with severe air unlikely at the moment.

Anumita Roychowdhury, executive director, research and advocacy at the Centre for Science and Environment (CSE) said Delhi’s air quality generally tends to return to the ‘severe’ category by the last week of December, as low temperatures combine with dense fog to trap pollutants. “Low temperatures slow down the air and the moisture content from the fog also traps pollutants. We may once again see a spell of severe air towards end December and early January,” said Roychowdhury.