Beyond stubble burning: What else is causing Delhi's air pollution?

The share of stubble burning in Delhi's pollution has averaged 18% the past one month. At its peak, stubble burning accounted for nearly half of Delhi's air pollution.

While stubble burning is undoubtedly a contributor to the pollution in the national capital, a Business Standard analysis shows that most of Delhi’s pollution is from other factors. An analysis of data available on the System of Air Quality and Weather Forecasting And Research (SAFAR) platform shows that over the last 30 days, the average share of stubble burning in Delhi’s PM2.5 concentration was just 18 per cent.

At its peak, however, stubble burning contributed to nearly half (48 per cent) of Delhi’s air pollution.

A Centre for Science and Environment study released last week found that nearly half of Delhi’s pollution from local sources had been coming from transport between October 24 and November 8, 2021.

SAFAR’s analysis in 2019, based on which the share of pollution is calculated, had found that transport and industry accounted for nearly 60 per cent share in PM2.5 emission during 2018-19. Two-fifths of the pollution came from transport alone. As per the SAFAR study, transport emissions had increased 40 per cent in 2018-19 compared to 2010-11, and industry emissions had witnessed a 48 per cent increase in the same period.

Although a category wise distinction of contributors to air pollution is not available daily, this share would have further increased in the following years, as vehicle registrations in Delhi have witnessed a jump. Between 2010-11 and 2018-19, vehicle registrations in Delhi had increased at a CAGR of 7.1 per cent per year. The compounded annual growth rate since 2018-19 has been almost similar despite the Covid-19 pandemic.

Data from IQAir also shows that transport may be one of the reasons for rising pollution levels. A proxy for increasing transport emissions is increasing nitrous oxide levels. Analysis of IQAir data shows that the average NO2 emissions had been the highest in the last week compared to all other days in the previous month.