New Delhi, Dec. 19 -- As Delhi slips once again into its familiar winter haze, the city's polluted air is no longer just a health statistic or a daily inconvenience - it is beginning to hollow out its social calendar. From marathons and cyclothons to concerts and cultural gatherings, organisers across the Capital are postponing or cancelling outdoor events as prolonged exposure to toxic air raises alarms for participants and audiences alike.

The growing list of cancellations comes amid repeated warnings from the Commission for Air Quality Management (CAQM) in NCR and Adjoining Areas. In November, the statutory body had written to the Delhi government and NCR state governments urging the postponement of physical sports competitions during...