With a sense of burning in their eyes and sore throat, people are finding it difficult to breathe as smoke emanating from burning seasonal crops and cow dung in the countryside have added to their woes.
Met office said winter weather patterns do not allow wind to circulate the air, causing the pollution to stay for a longer period.
They said smog gets formed by accumulation of pollutants in the air during this part of the year when temperatures are below normal with low wind speed and high moisture content. In dry weather, pollutants settle down or are blown away.
The blanket of smog engulfs parts of Uttar Pradesh as Delhi faces its worst smog in 17 years.
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