Special Issue on COVID-19 Aerosol Drivers, Impacts and Mitigation (X)

Hassaan Sipra1, Faheem Aslam2, Jabir Hussain Syed This email address is being protected from spambots. You need JavaScript enabled to view it.3, Tahir Mumtaz Awan2

1 Centre for Climate Research and Development, COMSATS University Park Road Tarlai Kalan, 45550 Islamabad, Pakistan
2 Department of Management Sciences, COMSATS University Park Road Tarlai Kalan, 45550 Islamabad, Pakistan
3 Department of Meteorology, COMSATS University Park Road Tarlai Kalan, 45550 Islamabad, Pakistan

Received: July 29, 2020
Revised: October 9, 2020
Accepted: October 13, 2020

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.

Download Citation: ||https://doi.org/10.4209/aaqr.2020.07.0459  

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Cite this article:

Sipra, H., Aslam, F., Syed, J.H., Awan, T.M. (2021). Investigating the Implications of COVID-19 on PM2.5 in Pakistan. Aerosol Air Qual. Res. 21, 200459. https://doi.org/10.4209/aaqr.2020.07.0459


  • We undertook analysis of PM2.5 before and during COVID-19 in Pakistan.
  • Multifractality was confirmed in all-time series of PM2.5 in Pakistan’s mega cities.
  • Lockdown was more effective in Karachi as compared to Lahore.
  • Highest multifractality was found during COVID-19.
  • This provides a baseline for policy effectiveness with reference to air quality.


There are profound impacts of Coronavirus disease-19 (COVID-19) globally, nationally and locally. To assess the impact of COVID-19 on the hourly concentrations of particular matter < 2.5 microns (PM2.5) in Lahore and Karachi, Pakistan, this study employs multifractal analysis. Comparative analysis of high frequency (hourly) PM2.5 data for both cities from February to April for 2019 and 2020 revealed inner dynamics of time series through seasonal and trend decomposition (STL) first, then multifractal detrended fluctuation analysis (MFDFA). The empirical findings confirmed existence of multifractality in hourly PM2.5. Based on multifractal properties, efficiency of Lahore declines during COVID-19. Furthermore, a varying impact of COVID-19 is found on the strength of multifractality of PM2.5 under consideration. Drastic, significant change is found on the efficiency of air quality in Lahore before and during COVID-19 periods. Before COVID-19, PM2.5 remains relatively efficient, while during COVID-19 period it shows high multifractality, the opposite of which is true for Karachi. However, all series exhibit anti-persistent (negatively correlated) behavior before and during COVID-19, with respect to the remainder component of PM2.5 concentration. This means that when PM2.5 concertation is high at a given time, in the next period, the concentration will be low. Intuitively, this is accurate, given that hourly PM2.5 concentrations change with economic activity, which oscillates in daily cycles of high and low PM2.5 concentrations. In Lahore significantly lower efficiency is observed during COVID-19; no conclusion on lockdown can be made. In Karachi, higher efficiency was achieved COVID-19, which was well correlated with the before COVID-19 period, implying effective lockdown policy. The confirmation and examination of multifractality in PM2.5 concentrations of Lahore and Karachi presents researchers and policymakers with a distinct signature for the impact of COVID-19. It provides validation for the development of such policy evaluation tools, with reference to air quality in Pakistan.

Keywords: PM2.5, Air quality, Multifractal analysis, COVID-19, Lockdown

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