Center for Science and Environment
The average intensity of the smog in Delhi so far is 329 micrograms per cubic meter per day. New Delhi: The first severe smog episode has hit Delhi and the National Capital Region (NCR) and is expected to last for two more days, the green think tank Center for Science and Environment (CSE) said today. Though seasonal smog in Delhi is intense, the average daily contribution of smoke from farm fires from mid-October to November 8 was the lowest in the past four years, it said. “Predictably, the first episode of the season was caused by the combined effect of adverse weather conditions (cool and calm winds and inversion), stubble burning and fireworks,” said Anumita Roychowdhury, executive director, research and advocacy, CSE. Compared to the first smog episode of the past four years, the current smog has the same duration as the first smog of the 2018 and 2020 season – both lasted for six days. If conditions don’t improve, it could catch up with the smog of 2019, which lasted eight days, the CSE said. The average intensity of the smog this year so far is 329 micrograms per cubic meter per day, which is lower than that of the 2020 smog (by 7 percent) and 2019 smog (by 3 percent). It is more intense than the smog of 2018 (about 9 percent). The persistence of this year’s smog despite relatively windy local conditions may be due to the city’s lack of pollution abatement measures, the green think tank said. “While very high concentrations of PM2.5 have attracted attention, levels of gases – ozone, CO or NO2 – have remained high during this smog episode. Also, the ratio of SO2 to NO2 increased on Diwali night, indicating an increased pollution load from fireworks. The PM2.5 concentration on Diwali night (8pm to 8am) is the most intense since 2017,” said Avikal Somvanshi, program manager, Urban Lab, CSE. This analysis is based on the real-time data available from the current air quality monitoring stations in Delhi-NCR and the greater Indo-Gangetic Plain. On average, the contribution of smoke to Delhi’s daily PM2.5 was the lowest in the past four years between mid-October and November 8. So far, it has recorded an average of 12 percent per day as opposed to 17 per cent per day in 2020, 14 percent per day in 2019 and 16 percent per day in 2018 (as reported by SAFAR), the CSE said. Converting it to absolute concentrations, the contribution of smoke per day this year was 26 micrograms per cubic meter, compared to 35 micrograms per cubic meter in 2020, 40 micrograms per cubic meter in 2019 and 31 micrograms per cubic meter in 2018 , it said. However, the peak contribution of smoke to Delhi’s PM level was recorded on Nov. 7 when it reached 48 percent. This is the second highest percentage of daily contributions since such an estimate was initiated by SAFAR in 2018. The highest one-day contribution rate was 58 percent on November 5, 2018.