External factors behind capital's 'very poor' AQI

The deterioration in Delhi's air quality, which was skirting the “very poor” category on Sunday, was caused more by external factors than from sources within the capital, according to the Centre's Decision Support System (DSS).

- Jasjeev Gandhiok

Data on Sunday showed at least 67.89% of Delhi's total PM2.5 contribution was from external sources.

The rest—32.11%—was a result of pollution sources within the capital, particularly vehicular emissions. Interestingly, stubble burning —a key contributor to Delhi's pollution load between October and November, was not among the top 5 contributors outside Delhi, adding only 2.06% of Delhi's total pollution load on Sunday. Instead, DSS data showed, the pollution from neighbouring NCR towns is a major contributing factor.

The DSS — the city’s only operational pollution-tracking model which gives an estimated contribution of sources to Delhi's PM 2.5 — was reactivated only earlier this month after it was suspended last year over inaccuracies.