NEW DELHI: The capital experienced near-zero visibility conditions till close to noon on Wednesday, the season’s most delayed lifting of dense fog that hit normal life and wreaked havoc on air, rail and road traffic in the region.
The foggy and humid conditions led to a sharp spike in air pollution, which crossed the ‘severe’ threshold by late evening, prompting the Commission for Air Quality Management (CAQM) to impose curbs under Grap-4, the highest pollution control measures that have been invoked after a gap of 22 days.
This brings back the ban on the plying of BS III petrol and BS IV diesel vehicles in Delhi and its neighbouring cities, and stops all construction activities, including linear public projects. It also mandates schools to operate in hybrid mode, giving the option of online classes to students.
Visibility dipped to zero from 8.30am to 11.30am, improving gradually in the subsequent hours.
Overcast skies pull max temp down sharply
Fog is expected to continue in the region, with the met department issuing a ‘yellow’ (be aware) alert for Thursday to Saturday for moderate to dense fog. Some areas received light rain in the evening.
R K Jenamani, senior IMD scientist, said visibility was in the range of 100-150 metres (dense fog) since 5.30am on Wednesday. “Dense fog intensified late morning on Wednesday with general visibility reducing to zero from 8.30am at both Safdarjung and IGI Airport. visibility dropped due to calm wind conditions and a stable surface atmospheric boundary layer. Easterly winds brought moisture which intensified the foggy conditions. Zero visibility with very dense fog conditions persisted at both Safdarjung and IGI Airport till 11.30 am,” said Jenamani.
This was the first time this season that dense fog had extended beyond 9.30am in the city, he said. By 12.30pm, visibility improved to 250-400 metres. Because of its persistence till late morning, Wednesday’s fog spell had a major impact on road, rail and air traffic. However, the most intense dense fog in terms of duration this season was recorded on Jan 4-5, which lasted for nearly nine hours from 11.30pm to 8.30am, according to IMD’s data.
Overcast skies during the day brought down the maximum temperature from 21.2 degrees Celsius on Tuesday to 18.1 degrees C, two notches below normal. The minimum temperature dipped to six degrees C, one degree below normal, compared to 8.9 degrees C a day earlier. Met department’s data shows that Palam, Pusa and Najafgarh recorded 0.5 mm rainfall each from 5.30pm to 8.30pm.
“There are chances of very light rain on Wednesday night and Thursday morning under the influence of a western disturbance. Another spell of very light to light rain is expected on Jan 21 night,” said a Met official. The fog spell is likely to continue.