Avoiding high ozone pollution in Delhi, India

Chen, Ying; Beig, Gufran; Archer‐Nicholls, Scott; Drysdale, Will S.; Acton, W. Joe F.; Lowe, Douglas; Nelson, Beth S.; Lee, James; Ran, Liang; Wang, Yu; Wu, Zhijun; Sahu, Saroj Kumar; Sokhi, Ranjeet S.; Singh, Vikas; Gadi, Ranu; Hewitt, C. Nicholas; Nemitz, Eiko; Archibald, A. T.; McFiggans, G.; Wild, Oliver

doi:10.1039/d0fd00079e

“…Decreased levels of NOx and VOCs during phase-I lockdown, along with increased light, led to increased O3 at the RK Puram site in Delhi. These results agree with recent modelling work that predicted O3 formation in Delhi is in the traditionally defined VOC limited regime 28 . Although VOC limited is the most common descriptor for this regime, it can also occur in areas with high VOC levels 29 .…”

Section: Effect Of Lockdown On Atmospheric Chemistry: Evidence For Local Ozone Production In Delhi Being Voc-limitedsupporting

confidence: 93%

Importance of Meteorology and Chemistry in Determining Air Pollutant Levels During COVID-19 Lockdown in Indian Cities

Crilley

¹

,

Iranpour²,

Young³

2021

Preprint

0

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To accurately quantify impact of short-term interventions (such as COVID-19 lockdown) on air pollutant levels, meteorology and atmospheric chemistry need to be considered in addition to emission changes. We demonstrate that regional sources have a significant influence on PM2.5 levels in Delhi and Hyderabad due to the small reduction calculated post-lockdown after weather-normalization, indicating that future PM2.5 mitigation strategies should focus on national-scale, as well as local sources. Furthermore, we demonstrate with field measurements that ozone production in Delhi is likely volatile organic compound (VOC)-limited, in agreement with previous modelling predictions, indicating that ozone mitigation should focus on dominant VOC sources. This work highlights the complexity in developing mitigation strategies for air pollution due to its non-linear relationships with emissions, chemistry and meteorology.

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“…Decreased levels of NOx and VOCs during phase-I lockdown, along with increased light, led to increased O3 at the RK Puram site in Delhi. These results agree with recent modelling work that predicted O3 formation in Delhi is in the traditionally defined VOC limited regime 28 . Although VOC limited is the most common descriptor for this regime, it can also occur in areas with high VOC levels 29 .…”

Section: Effect Of Lockdown On Atmospheric Chemistry: Evidence For Local Ozone Production In Delhi Being Voc-limitedsupporting

confidence: 93%

Importance of Meteorology and Chemistry in Determining Air Pollutant Levels During COVID-19 Lockdown in Indian Cities

Crilley

¹

,

Iranpour²,

Young³

2021

Preprint

0

View full text Add to dashboard Cite

To accurately quantify impact of short-term interventions (such as COVID-19 lockdown) on air pollutant levels, meteorology and atmospheric chemistry need to be considered in addition to emission changes. We demonstrate that regional sources have a significant influence on PM2.5 levels in Delhi and Hyderabad due to the small reduction calculated post-lockdown after weather-normalization, indicating that future PM2.5 mitigation strategies should focus on national-scale, as well as local sources. Furthermore, we demonstrate with field measurements that ozone production in Delhi is likely volatile organic compound (VOC)-limited, in agreement with previous modelling predictions, indicating that ozone mitigation should focus on dominant VOC sources. This work highlights the complexity in developing mitigation strategies for air pollution due to its non-linear relationships with emissions, chemistry and meteorology.

show abstract

“…S1 - S5 , shows how the O 3 levels increase in most of the cities and, at the same time, decrease in NO 2 concentration levels. Through these trends and previously conducted studies by Chen et al ( 2021 ), it is precedent that the O 3 production in Indian urban cities is VOC-limited. These results indicate that there is a need to control VOC production alongside PM and NO 2 .…”

Section: Resultssupporting

confidence: 53%

Urban air pollution reduction: evidence from phase-wise analysis of COVID-19 pandemic lockdown

Yadav

¹

,

Sharma

²

,

Kumar

³

et al. 2021

Arab J Geosci

2

0

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Until 31 May 2020, more than six million confirm COVID-19 cases had been reported worldwide. Lockdown has resulted in significant air quality improvement, especially in urban regions. The lockdown has acted as a natural experiment empowering researchers, policymakers, and governing bodies. The present study focuses on quantifying and analysing the effect of lockdown on India's metropolitan cities, namely New Delhi, Mumbai, Kolkata, Chennai, and Bangalore. The study analyses the phase-wise and diurnal variations in the air quality from 24 March 2020 to 31 May 2020 while focussing on-peak and off-peak duration concentrations. To investigate the reason behind pollutant reduction, correlation of drop percentages in pollutant concentrations with vehicle population, extent of construction activity, and meteorological parameters are analysed. The 24-h drop in PM 10 and PM 2.5 showed a high correlation (R 2 = 0.97 and 0.72, respectively) with the city's vehicle population. During peak hours, the inland cities (Delhi and Bangalore), with a more extensive vehicle fleet, recorded a higher drop in PM 10 and PM 2.5 concentrations than coastal cities (Mumbai, Chennai, and Kolkata). With respect to 2019 concentration, the maximum decrease in pollutant concentrations averaged across the five study locations was recorded in NO 2 (46%), followed by PM 2.5 (40%), PM 10 (37%), and CO (19%). SO 2 and O 3 contrarily recorded an overall increase of 40% and 41%. These results wherein vehicular pollutants recorded the maximum drop indicate that reduced vehicular traffic primarily influenced air quality improvement during the lockdown.

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Avoiding high ozone pollution in Delhi, India

Abstract: Surface ozone is a major pollutant threatening public health, agricultural production and natural ecosystems. While measures to improve air quality in megacities such as Delhi are typically aimed at reducing...

Cited by 54 publications

References 48 publications

Importance of Meteorology and Chemistry in Determining Air Pollutant Levels During COVID-19 Lockdown in Indian Cities

Importance of Meteorology and Chemistry in Determining Air Pollutant Levels During COVID-19 Lockdown in Indian Cities

Importance of Meteorology and Chemistry in Determining Air Pollutant Levels During COVID-19 Lockdown in Indian Cities

Urban air pollution reduction: evidence from phase-wise analysis of COVID-19 pandemic lockdown

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