Several cities in Uttar Pradesh on Wednesday faced dangerous levels of pollution after the spell of favourable meteorological conditions and a smattering of rain that led to an improvement in the air quality in Delhi ended.
The change in meteorological conditions, especially the inflow of moisture carrying winds, impacted other cities in the Indo-Gangetic plain more than the national capital.
Despite facing similar meteorological conditions as Delhi, some cities in the region have worse air quality as they are heavily influenced by local factors.
Kanpur, Ghaziabad, Muzaffarpur and Varanasi experienced severe air pollution levels on Wednesday afternoon, with Air Quality Index, a measure of air quality, recorded between 400-500, the worst category.
High wind speeds were suspending the already present dust in Ghaziabad, according to D Saha at the Central Pollution Control Board’s Air quality lab. Ghaziabad recorded an AQI of 453 on Wednesday afternoon.The alluvial soil of the Indo-Gangetic plain throws up very fine dust particles.
“Earlier, because there was water in the rivers it would absorb the pollution. Now there is less water so the river bed is dry, adding to the pollution,” Saha explained.
{{/usCountry}}“Earlier, because there was water in the rivers it would absorb the pollution. Now there is less water so the river bed is dry, adding to the pollution,” Saha explained.
{{/usCountry}}Experts said recent rains, the inflow of northerly winds, moderate wind speeds and low humidity contributed to the improved air quality in the Delhi.
“Because of a change in wind direction, humidity has increased and wind speeds have slowed leading to an increase in pollution levels,” Mahesh Palawat, at Skymet Weather, a private forecasting agency, said.
“The spell of poor air quality is expected to last till Dec 22-23,” he added.
The northerly winds that blow from inland do not bring moisture. However, in November due to stubble burning in neighbouring states upwind, northwesterly winds were bringing more pollutants.
The south and south-easterly winds are now dominating bringing in some moisture that allows pollutants to settle near the surface.
“North winds are the safe winds for Delhi. It only brings dilution in the air,” Saha said.
Moderate wind speeds allow for the dispersion of pollutants and the wind speeds have slowed in the past 24 hours, leading to a pollution build up.