New Delhi, Nov 12 (IANS): The air quality in Delhi post-Diwali on Thursday was "very poor", data showed.

The System of Air Quality and Weather Forecasting and Research (SAFAR), of the ministry of earth sciences, said the PM 2.5 level -- particulate matter with a diameter smaller than 2 1/2 microns, which can cause difficulty in breathing -- was at 229.5 units.

It said the air quality was "very poor".

These PM2.5 levels touched alarming levels of over 400 units around 11 p.m. on Wednesday on Diwali night -- falling under "severe" air quality.

SAFAR had said before Diwali that the PM 2.5 levels could reach as high as 429 units, registering a "critical" quality of air. It also predicted that the air levels would remain "poor" for the next three days.

According to the Delhi Pollution Control Committee, data at around 1.30 p.m. on Thursday from the air quality monitoring station at Anand Vihar in east Delhi showed a high 206 units of PM 2.5 levels, Punjabi Bagh in west Delhi at 172 units and R.K. Puram in south Delhi at 116 units as against the prescribed normal of 60 units.