NEW DELHI  Authorities in the Indian capital New Delhi implemented additional curbs including shutting schools until further notice and banning the entry of non-essential trucks due to toxic smog that worsened the air quality to "severe plus" category. For many days now, several northern Indian cities have been witnessing toxic levels of air pollution, with the air quality index (AQI) in Delhi rising to 457 on Sunday evening, prompting authorities to announce more curbs in Delhi and neighboring