Can Delhi's Pollution be Affected by Crop Fires in the Punjab Region?

Self Cite

105

Delhi, a tropical indian megacity, experiences one of the most severe air pollution in the world, linked with diverse anthropogenic and biomass burning emissions. First phase of COVID-19 lockdown in India, implemented during 25 March to 14 April 2020 resulted in a dramatic near-zeroing of various activities (e.g. traffic, industries, constructions), except the "essential services". Here, we analysed variations in the fine particulate matter (PM 2.5) over the Delhi-National Capital Region. Measurements revealed large reductions (by 40-70%) in PM 2.5 during the first week of lockdown (25-31 March 2020) as compared to the pre-lockdown conditions. However, O 3 pollution remained high during the lockdown due to non-linear chemistry and dynamics under low aerosol loading. Notably, events of enhanced pM 2.5 levels (300-400 µg m −3) were observed during night and early morning hours in the first week of April after air temperatures fell close to the dew-point (~ 15-17 °C). A haze formation mechanism is suggested through uplifting of fine particles, which is reinforced by condensation of moisture following the sunrise. The study highlights a highly complex interplay between the baseline pollution and meteorology leading to counter intuitive enhancements in pollution, besides an overall improvement in air quality during the COVID-19 lockdown in this part of the world. The pandemic due to spread of novel Corona virus, commonly known as the COVID-19, has led to partial or complete lockdown in several countries around the world. The spread of deadly virus has caused deaths estimated to more than two hundred thousand people over a period of December 2019-April 2020. However, air pollutants and COVID-19 are linked to have played a major role in huge number of deaths 1,2. In order to contain its impact in India, the first phase of complete lockdown imposed from 25 March to 14 April 2020, which was further extended till 03 May 2020. As a result, the transport, construction works, industries and other commercial activities, which could have injected pollutants or produce dust, are stopped and remained at its minimal level. Unprecedented reductions in anthropogenic activities yielded to very low values of emissions resulting in significantly improved air quality over the Delhi-National Capital Region (NCR) [up to 50% reduction in fine particle

Section: Introductionmentioning

confidence: 99%

PM2.5 diminution and haze events over Delhi during the COVID-19 lockdown period: an interplay between the baseline pollution and meteorology

Dhaka

Chetna

Kumar

et al. 2020

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105

“…Almost all the devices were installed in farmers' houses in farming villages, and locations were selected away from large roads or other sources of pollution by checking Google maps. Referring to the air mass pathways shown by Takigawa and coworkers 8 , we divided the target region into 30 grids and designed the network so that each grid would have at least one site. The existing monitoring stations of the Central Pollution Control Board (CPCB) are located around large cities in the region (Fig.…”

Section: Resultsmentioning

confidence: 99%

Very high particulate pollution over northwest India captured by a high-density in situ sensor network

Singh,

Matsumi,

Nakayama

et al. 2023

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Exposure to particulate matter less than 2.5 µm in diameter (PM2.5) is a cause of concern in cities and major emission regions of northern India. An intensive field campaign involving the states of Punjab, Haryana and Delhi national capital region (NCR) was conducted in 2022 using 29 Compact and Useful PM2.5 Instrument with Gas sensors (CUPI-Gs). Continuous observations show that the PM2.5 in the region increased gradually from < 60 µg m−3 in 6–10 October to up to 500 µg m−3 on 5–9 November, which subsequently decreased to about 100 µg m−3 in 20–30 November. Two distinct plumes of PM2.5 over 500 µg m−3 are tracked from crop residue burning in Punjab to Delhi NCR on 2–3 November and 10–11 November with delays of 1 and 3 days, respectively. Experimental campaign demonstrates the advantages of source region observations to link agricultural waste burning and air pollution at local to regional scales.

“…Delhi, being the second most populated megacity in the world, faces a range of environmental challenges including adverse air pollution episodes particularly during the winter season 1 – 5 . Exposure of large fraction of the population to poor air quality, pose a higher health risk 6 – 10 .…”

Section: Introductionmentioning

confidence: 99%

Performance of high resolution (400 m) PM2.5 forecast over Delhi

Jena

Ghude

Kumar

et al. 2021

This study reports a very high-resolution (400 m grid-spacing) operational air quality forecasting system developed to alert residents of Delhi and the National Capital Region (NCR) about forthcoming acute air pollution episodes. Such a high-resolution system has been developed for the first time and is evaluated during October 2019-February 2020. The system assimilates near real-time aerosol observations from in situ and space-borne platform in the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) to produce a 72-h forecast daily in a dynamical downscaling framework. The assimilation of aerosol optical depth and surface PM2.5 observations improves the initial condition for surface PM2.5 by about 45 µg/m3 (about 50%).The accuracy of the forecast degrades slightly with lead time as mean bias increase from + 2.5 µg/m3 on the first day to − 17 µg/m3 on the third day of forecast. Our forecast is found to be very skillful both for PM2.5 concentration and unhealthy/ very unhealthy air quality index categories, and has been helping the decision-makers in Delhi make informed decisions.