An Indigo plane lands amidst evening smog at the Delhi airport in New Delhi, India, Thursday, Oct. 31, 2019. Two days after Diwali festival, Delhi's air quality continued to hover between the 'very poor' and 'severe' category. (AP Photo/Manish Swarup)
An Indigo plane lands amid evening smog at Delhi's airport on Thursday, October 31. AP

Dozens of flights disrupted as New Delhi smog reaches critical levels