NEW DELHI - Residents of India’s capital, Delhi, woke up to smoky skies as air quality dropped after the festival of Diwali. People in the city burst crackers late into Sunday night despite a ban on fireworks due to high pollution levels. Delhi has been battling toxic air for weeks, with the government announcing an early winter break for schools in an effort to protect children. The city has high pollution through the year due to factors including vehicular emissions and dust. But the problem becomes worse in winter as farmers in neighbouring states burn crop stubble. Low wind speeds also trap pollutants - such as those produced by firecrackers - in the lower atmosphere, making it hard to breathe. On Monday afternoon, according to the federal government’s Safar app, the Air Quality Index (AQI) in Delhi was 445, with some places recording readings above 520. The AQI measures the level of PM 2.5 - fine particulate matter that can clog lungs and cause a host of diseases - in the air. Levels between 101 and 200 are considered moderate, while those between 201 and 300 are poor. Between 301 and 400 is categorised as “very poor” and a figure higher than 400 is considered “severe”.