Delhi's AQI post-Diwali 642, almost double 2017's 367

Delhi's pollution level post-Diwali nearly doubled in comparison to last year as people burst firecrackers before and after the Supreme Court stipulated time frame of 8 pm to 10 pm.

The overall air quality index (AQI) Thursday was recorded in the "severe plus emergency" category at 642, according to Centre-run System of Air Quality and Weather Forecasting and Research (SAFAR) data.

In 2017, the AQI was recorded at 367, a day after Diwali, while in 2016 it was 425. The AQI this year was over twice that of 2017.

A "severe plus emergency" AQI essentially means that even healthy people may suffer from respiratory illnesses on prolonged exposure. This air will seriously affect those with ailments, according to a SAFAR advisory.

The Supreme Court had allowed people to burst firecrackers from 8 pm to 10 pm only on Diwali and other festivals. The top court also allowed manufacture and sale of just "green crackers" which have low emission of light, sound and harmful chemicals.

Central Pollution Control Board (CPCB) data said particulate concentrations were slightly higher this Diwali as compared to last year.

"Last year Diwali was observed on October 19 whereas this year, the festival was celebrated on November 7 which has different meteorological conditions that govern the dispersion pattern of pollutants," the CPCB said.

It admitted that the severe deterioration of air quality was due to unfavourable conditions coupled with pollutants generated from firecrackers.

However, the CPCB said when compared with the average particulate matter data during November 1 to 7 last year with the same period this year, the city average particulate concentration for Delhi was lower in 2018.

It said that it can be observed that all the pollutants reported higher values at all the stations if compared with 2017 data for pre-Diwali.

"This may be due to the differences in background air quality status in October and November. Meteorology as well as stubble burning makes huge difference in Delhi's air quality in late October and November.

"This year, Diwali day shows that the PM10 and PM2.5 values have increased this year compared to 2017. However, the data are similar to Diwali day of 2016 which was observed on October 30," the CPCB data said.

Giving a break up of different areas, the CPCB said in Pritampura, the PM10 and PM2.5 levels was 831 and 990 respectively this year, while last year the PM10 and PM2.5 was recorded at 677 and 690 respectively.

In Janakpuri, the PM10 and PM2.5 levels was 1076 and 998 respectively this year, while last year it was recorded at 706 and 638 respectively