Air trap around Delhi may stay for a week

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[google-translator]

There may be no respite for the next seven days from the toxic smoke and hazardous pollution levels, scientists at the India Meteorological Department (IMD) warned, and added that weather conditions unfavourable to the dispersal of pollutants are likely to continue for a week.

Delhi environment minister Gopal Rai blamed the stubble fires in Punjab and Haryana for the persistent pollution episode, and said the state governments did little to prevent the annual fire incidents.(HT)
Delhi environment minister Gopal Rai blamed the stubble fires in Punjab and Haryana for the persistent pollution episode, and said the state governments did little to prevent the annual fire incidents.(HT)

VK Soni, head of IMD’s environment and research department, said calm local winds were trapping pollution from stubble fires in Punjab and Haryana, and the Capital’s local pollution closer to the surface. High moisture levels have worsened this condition, as it helps pollutants stay suspended close to the surface.

“After Diwali, when cracker smoke and stubble fires peaked, the winds have remained slow, which resulted in an accumulation of pollutants. On Friday, during the day, the wind speed was only around 6kmph, and after sundown it became even more calm. Similar, conditions are being seen over the last few days,” said Soni.

IMD data shows that the relative humidity in Delhi at 8.30am on Friday was 93%. As the day progressed the humidity levels came down to 69%, but still stayed unfavourable for dispersal of the pollutants.

A Indian Institute of Tropical Meteorology (IITM) scientist explained that when moisture content increases in the air, the secondary pollution particles—particles that are formed by chemical reactions in the atmosphere—swell up in size.

“As they grow bigger by absorbing moisture, the pollutants and particles block the sunlight from reaching the surface and form a hazy blanket,” the scientist explained, asking not to be named. As the sunlight stays away, the air stays cold and dense making it difficult for the pollutants to disperse.

He added that such conditions are rare for this time of the year, and are usually seen by November-end or December.

“These conditions are abnormal. During this time of the year, while pollution levels do spike, we get a few bouts of moderate to high speed winds that facilitate pollution dispersion. But that has not happened this time and consistently, the winds have remained stable,” the scientist added.

Mahesh Palawat, vice-president (meteorology and climate change), Skymet Weather Services, said Delhi is yet to receive any western disturbance this month, which either brings rain to clear the air or improves wind speed. He also said that the weather condition where two winds—northwesterly from Punjab and Haryana and southeasterly from a depression over the Bay of Bengal—are colliding over the city is also continuing, creating a barrier for the movement of pollutants.

“This time in November, we are yet to see a western disturbance, and there is no forecast for at least the next five days. Usually, we see around two to three western disturbances by this time. This year, it last happened on October 24,” Palawat said.

Delhi environment minister Gopal Rai blamed the stubble fires in Punjab and Haryana for the persistent pollution episode, and said the state governments did little to prevent the annual fire incidents. He added that strict directions have been issued to all agencies in the city to control local pollution sources so that the air quality does not worsen.

“The current levels of pollution are spiking due to the consistent increase in stubble burning from Punjab, Haryana, and Uttar Pradesh. It has been reported that a total of 45,000 stubble burning incidents have been reported till now from these regions. The impact of these fires is being witnessed by the people of Delhi as the air accumulates more pollution,” Rai said.

He also said government is implementing anti-dust campaign, anti-burning campaign, and the Red Light On, Gaadi Off campaign to control pollution from local sources.

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