CSE’s new assessment says that the first smog episode of the season has knocked in Delhi-NCR

Smog has also covered the entire Indo-Gangetic plain.

The duration of the ongoing smog episode is expected to exceed seven days.

Adverse weather conditions, farm fires and Diwali crackers have triggered the first episode, with the contribution of farm fires being the lowest in the last four years.

A deeper analysis dispels the myth that winter pollution is only a particulate problem – it is also a harmful cocktail of toxic gases including ozone, carbon monoxide, nitrogen dioxide and sulfur dioxide.

The concentration of 5 on Diwali night (8 pm to 8 pm) has been the highest since 2017, while the proportion of sulfur dioxide and nitrogen oxide has been high, indicating the effect of crackers.

The current severe smog episode requires immediate emergency measures in all areas to prevent further pollution and worsening of the situation, while a long-term strategy needs to be implemented immediately.

New Delhi, November 10, 2021: The first severe smog episode has reached Delhi and the National Capital Region (NCR) and is expected to last for the next two days. A new analysis by the Center for Science and Environment (CSE) shows that smog has engulfed the entire Indo-Gangetic plain. The region is in the grip of a public health emergency and urgent and drastic measures are needed to reduce the pollution peak.

“Predictably, the first episode of the season has started with a combined effect of unfavorable weather conditions (cool and calm winds and inversion), stubble burning and firecrackers. But even though the seasonal haze in Delhi is intense, from mid-October to November 8, The average daily contribution of farm stubble smoke to 2021 has been the lowest in the past four years. But since November 6, its contribution has risen to 48 per cent on November 7, and is still high,” the permission said. Roychowdhury, executive director, research and advocacy, CSE.

“While very high concentrations of PM2.5 have attracted attention, levels of gases – ozone, CO or NO2 – remained elevated during this smog episode. Also, the ratio of SO2 to NO2 increased on Diwali night , which reflects the rising pollution load from crackers. The concentration of PM2.5 on Diwali night (8 pm to 8 am) has been the highest since 2017,” said Avikal Somvanshi, Program Manager, Urban Lab, CSE it is said.

The analysis is based on real-time data available from currently operational air quality monitoring stations in Delhi-NCR and the larger Indo-Gangetic plain. For this analysis, a large amount of data points have been cleaned and data gaps have been addressed based on the USEPA method. The analysis covers 156 Continuous Ambient Air Quality Monitoring Stations (CAAQMS) spread across 67 cities in Punjab, Chandigarh, Haryana, Delhi, Rajasthan, Uttar Pradesh, Bihar and West Bengal.

The meteorological data for analysis has been taken from the Palam Meteorological Center of the India Meteorological Department (IMD). Fire count data were obtained from NASA’s Fire Information for Resource Management System, specifically, using the Visible Infrared Imaging Radiometer Suite (VIIRS) product. The contribution of farm stubble smoke to Delhi’s air quality has been estimated from the System of Air Quality and Weather Forecasting and Research (SAFAR) of the Ministry of Earth Sciences.

First smog of the season: PM2.5 concentration in Delhi exceeded 250 micrograms per cubic meter (ug/m3) (breakpoint for severe AQI category) on November 4 and continues to hover above it seven days later. Its maximum concentration was 501 ug/m3 on 5 November, then gradually decreased to 256 ug/m3 on 8 November. Since then, it has started climbing again and stood at 264 ug/m3 on 9 November. Hourly levels are rising again on 10th November (checked by 10am) and if weather conditions do not improve, 10th November could also exceed the 24-hour average of 250 ug/m3.

It is to be noted that the CSE evaluation is based on monitoring in Delhi alone and the daily average is assumed from midnight to midnight, which is different from the methodology of CPCB. The CPCB uses the GRAP for its trend counter, uses the average of all stations in Delhi and NCR cities, while the CPCB uses the AQI bulletin from 4 pm to 4 pm as a measure of its daily value. Is.

Compared to the first smog episode of the previous four years, the current smog corresponds to the first smog period of the 2018 and 2020 seasons – both lasting six days. If the situation does not improve, it may overtake the eight-day smog of 2019.

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