Air and train services were badly hit when fog enveloped Delhi and its surrounding areas early on Tuesday.
After a few days of relief, flight operations at the Indira Gandhi International Airport were suspended for almost three hours from 0545 IST as visibility dropped to near zero and the Runway Visibility Range fluctuated between 100 and 200 metres, an Airport Authority of India spokesman said.
The RVR improved to 900 metres after 0830 IST and flight operations returned to normal.
Railway services were also badly hit, with seven trains being cancelled.