Delhi air quality slipped to ’severe’ again but likely to improve marginally next week

Delhi's air quality slipped again to the 'severe' category on Friday. The overall air quality index (AQI) in the national capital stood at 401 at 8 am. It worsened to 415 by 4 pm, news agency PTI reported. However, it improved slightly to 392 around 10:30 pm on Friday, according to the System of Air Quality and Weather Forecasting And Research (SAFAR).

An AQI between zero and 50 is considered 'good', 51 and 100 'satisfactory', 101 and 200 'moderate', 201 and 300 'poor' , 301 and 400 'very poor', 401 and 450 'severe' and above 450 'severe-plus'.

Delhi has been seeing a gradual increase in the AQI levels after a marginal improvement was witnessed on Sunday. The 24-hour average AQI, recorded at 4 pm every day, was 390 on Thursday, 394 on Wednesday, 365 on Tuesday, 348 on Monday and 301 on Sunday.

Meanwhile, the air quality early warning system, developed by the Pune-based Indian Institute of Tropical Meteorology, revealed that pollution levels are likely to oscillate in the 'very poor' to 'severe' categories in the next few days.

According to news agency PTI, a scientist at the India Meteorological Department (IMD) also predicted a brief relief due to a likely improvement in meteorological conditions under the influence of a western disturbance — which is expected to affect northwest India starting November 27.

What's causing air pollution in Delhi now?

The spike in the AQI levels was seen after the Centre removed stringent curbs — including a ban on construction work related to linear projects and the entry of polluting trucks in Delhi — on Saturday.

Meanwhile, data showed by a joint project by the Delhi government and the Indian Institute of Technology (IIT), Kanpur, revealed that vehicular emissions accounted for about 38 per cent of the capital's air pollution on Thursday, November 23, PTI reported.

Secondary inorganic aerosols are the second major contributor to Delhi's foul air, accounting for 25 to 35 per cent of the air pollution in the city over the last few days. the report said. Inorganic aerosols are particles such as sulfate and nitrate that are formed in the atmosphere due to the interaction of gases and particulate pollutants from sources like power plants, refineries and vehicles.

Biomass burning, including post-harvest paddy straw burning in neighbouring states, contributed 21 per cent to the capital's air pollution the previous day.

Earlier in the day, Delhi Environment Minister Gopal Rai conducted a meeting on increasing pollution in the city despite fewer incidents of stubble burning and pointed out two factors behind it.

"The incidents of stubble burning are very few now, and the level of pollution is still increasing. Scientists reported two-three factors for this. The first is that vehicle pollution's contribution is 36 per cent. The second factor is biomass burning," Rai said.

"We made some major decisions after seeing this. To control vehicle pollution, we issued the rules of GRAP 3. To control biomass burning, we have directed the related organisations to monitor this especially. especially the MCD, Revenue, DDA, and NDMC, are being given this direction for the fires that are breaking out at various places in the parks," Gopal Rai was quoted by PTI as saying.

(With inputs from PTI)