Air pollution in Delhi-NCR nears 'emergency' zone; schools shut till Friday

The extreme condition has prompted the authorities to order closure of schools till November 15 -- a second time in two weeks

Delhi and places nearby were engulfed in a smog on Thursday as air pollution reached emergency levels, prompting authorities to shut schools and warn that a traffic rationing measure could be extended.

Air quality index (AQI) in the national was 472 with particulate matter (PM) 2.5 levels at 322 and PM 10 levels at 487 at 6:30 am on Thursday.

An AQI between 201 and 300 is considered 'poor', 301-400 'very poor' and 401-500 'severe'. An AQI above 500 falls in the 'severe plus' category.Particulate matter is the sum of all solid and liquid particles suspended in air many