Between January and October 2016, air quality was either ‘poor’, ‘very poor’ or ‘severe’ on 184 of the total 305 days; experts say situation to get worse.

Following the spike in concentration of pollutants on Diwali night, public discourse and panic regarding poor air quality has taken centre stage in Delhi.

However, the danger is not new, but has been spread across the year: for the most part of 2016, Delhiites have been inhaling harmful air.

Between January and October 2016, the air quality was ‘poor’, ‘very poor’ or ‘severe’ — classification as per National Air Quality Index (NAQI) — on 184 of the total 305 days, The Hindu’s analysis of air quality data shows. This is around 60 per cent of the days in the ten months of the year. It is likely to get worse in the remaining two months. The trend from previous years suggests that as winter sets in, air quality will further decline.

For the analysis, data was sourced from the NAQI portal maintained by the Centre. AQI value for Delhi was computed by taking the average of all pollution monitoring stations in the city for which data was available.

Not a single day had ‘good’ air quality. There were 99 ‘moderate’ days and 20 ‘satisfactory’ days. This was mostly in July, August and September: the three months which together had just five ‘poor’ air quality days.

Air quality started getting worse from the beginning of October. There were 22 ‘poor’ days. Another seven days — almost all in the last week, in the run-up to Diwali — were ‘severe’ and ‘very poor’.

Overall, there were 64 days when air quality was ‘severe’ or ‘very poor’, which is around 20 per cent of the total days in the ten months. Twenty-nine of the 31 days in January fell into this category, making it the worst month of the year so far.

Grim outlook

As winter sets in, air quality declines. The trend is the same every year, Anumita Roychowdhury from the Center for Science and Environment (CSE) told The Hindu .

The situation this year, however, appears to be more damning. Numbers show that pollution levels this Diwali are worst than last year, even though it came earlier.

“This is making everyone more concerned. There is lot more awareness about air pollution now and we are finding ourselves unprepared for the situation,” Ms. Roychowdhury said.

Following the intervention by the Supreme Court and all the noise that was created last year, Ms. Roychowdhury said that there was a lot of hope that “we will have enough time to prepare ourself for the winter of 2016. But that hasn’t happened”.

In an event organised by CSE earlier this year, Chief Minister Arvind Kejriwal had said that his government has the political will to fight air pollution. “Political will needs to be much stronger and public support needs to be built for hard action,” Ms. Roychoudhury said, adding: “a lot of chest beating happens over air pollution but that doesn’t translate into support for hard decisions.”

Diwali and crackers make the poor quality air starkly visible, but the threat is never really gone.