Department of Civil Engineering, Chittagong University of Engineering and Technology, Chatttogram, Bangladesh


Air pollution has become a serious concern for its potential health hazard, however, often got less attention in developing countries, like Bangladesh. It is expected that worldwide lockdown due to COVID-19 widespread cause reduction in environmental pollution in particularly the air pollution: however, such changes have been different in different places. In Chittagong, a city scale lockdown came in force on 26 March 2020, a week after when first three cases of COVID-19 have been reported in Bangladesh. This study aims to statistically evaluate the effects of COVID-19 lockdown (26 March to 26 April 2020) on selected air quality pollutants and air quality index s. The daily average concentrations of air pollutants PM10, PM2.5, NO2, SO2 and CO of Chittagong city during COVID-19 lockdown were statistically evaluated and were compared with dry season data averaging over previous 8 years (2012 to 2019). During lockdown, except NO2, all other pollutants studied showed statistically significant decreasing trend. During the COVID-19 shutdown notable reduction of 40%, 32% and 13% compared to the daily mean concentrations of these previous dry season were seen for PM2.5, PM10 and NO2, respectively. The improvement in air quality index value was found as 26% in comparison to the previous dry season due to less human activities in COVID-19 shutdown. The factor analysis showed that AQI in Chittagong city is largely influenced by PM10 and PM2.5 during COVID-19 shutdown. The lesson learnt in this forced measure of lockdown is not surprising and unexpected. It is rather thought provoking for the decision makers to tradeoff the tangible air quality benefits with ongoing development strategies’ that was often overlooked directly or indirectly. 

Graphical Abstract

Statistical evaluation of selected air quality parameters influenced by COVID-19 lockdown


  • Impacts on air pollutants (both gaseous and particulate matter) due to measures taken during COVID-19 lockdown has been analyzed; 
  • Due to COVID-19 lockdown in Chittagong city, 40% and 30% reduction of the mean concentration were found for PM2.5 (μg/m3) and PM10 (μg/m3) respectively; 
  • Air Quality Index improved by 26% during COVID-19 lockdown although NO2 (μg/L) showed increasing trend even in COVID-19 lockdown period.


Begum, B.A.; Hopke, P.K., (2018). Ambient air quality in Dhaka, Bangladesh over two decades: Impacts of policy on air quality. Aerosol Air Qual. Res., 18(7): 1910–1920 (11 pages).

CASE, (2019a). Ambient air quality in Bangladesh. Dhaka.

CASE, (2019b). Sources of air pollution in Bangladesh, Clean Air and Sustainable Environment Project, Department of Environment. Dhaka.

Dantas, G.; Siciliano, B.; Boscaro França, B.; da Silva, C.M., Arbillaa, G., (2020). The impact of COVID-19 partial lockdown on the air quality of the city of Rio de Janeiro, Brazil. Sci. Total Environ., 729: 139085. (10 pages).

EPA, (2006). Guidelines for reporting of daily air quality - Air Quality Index (AQI). North Carolina U.S.

Haque, M.; Ahamad, R., (2020). Over 500 RMG units reopen in Bangladesh amid coronavirus risks. NEWAGE.

IEDCR, (2020). Distribution of confirmed cases in Bangladesh, Institute of Epidemiology, Disease Control and Research.

Jain, S.; Sharma, T., (2020). Social and travel lockdown impact considering Coronavirus Disease (COVID-19) on Air Quality in Megacities of India: Present Benefits, Future Challenges and Way Forward.  Aerosol Air Qua. Res., 20: 1222–1236 (15 pages).

Kerimray, A.; Baimatova, N.; Ibragimova, O.P.; Bukenov, B.; Kenessov, B.; Plotitsyn, P.; Karaca, F., (2020). Assessing air quality changes in large cities during COVID-19 lockdowns: The impacts of traffic-free urban conditions in Almaty, Kazakhstan. Sci. Total Environ., 730: 139179 (11 pages).

Mahapatra, S.S.; Sahu, M.; Patel, R.K.; Panda, B.N., (2012). Prediction of water quality using principal component analysis. Water Qual. Exposure Health., 4(2): 93–104 (12 pages).

Motalib, M.A.; Lasco, R.D., (2015). Assessing air quality in Dhaka City. Int. J. Sci. Res., 4(12): 1908–1912 (5 pages).

Muhammad, S.; Long, X.; Salman, M., (2020). COVID-19 pandemic and environmental pollution: A blessing in disguise? Sci. Total Environ., 728: 138820 (5 pages).

Otmani, A.; Abdelfettah, B.; Tahri, M.; Bounakhla, M.; Chakir, M.;El Bouch, M.; M'hamed Krombid, M., (2020). Impact of Covid-19 lockdown on PM10, SO2 and NO2 concentrations in Salé City (Morocco) in Salé city . Sci. Total Environ., 735(2): 139541 (5 pages).

Rahman, M.H.; Al-Muyeed, A., (2016). Urban air pollution: A Bangladesh perspective. WIT Transactions Ecol. Environ., 82: 1743–3541 (9 pages).

Sharma, S.; Zhang, M.; Anshika; Gao, J.; Zhang, H.; Kota, S.H., (2020). Effect of restricted emissions during COVID-19 on air quality in India. Sci. Total Environ., 728: 138878 (5 pages).

Shawon, A.A., (2020). Coronavirus: Bangladesh declares public holiday from March 26 to April 4, Dhaka tribune.

Sneyers, R., (1990). On the statistical analysis of series of observations. Geneva, Secretariat of the World Meteorological Organization.

Tobías, A.; Carnerero, C.; Reche, C.; Massagué, J.; Via, M.; Minguillón, M.C.; Alastuey, A.; Querol, X., (2020). Changes in air quality during the lockdown in Barcelona (Spain) one month into the SARS-CoV-2 epidemic. Sci. Total Environ., 726: 138540 (14 pages).

WHO, (2016). WHO global urban ambient air pollution Database.

Xu, K.; Cui, K.; Young, L.H.; Hsieh, Y.K.; Wang, Y.F.; Zhang, J.; Wan, S., (2020). Impact of the COVID-19 Event on Air Quality in Central China. Aerosol Air Qual., Res., (2): 915–929 (15 pages).

Zahangir, M.; Sarker, A.; Alam, M., (2001). Air pollution due to vehicle exhaust in Dhaka City. In 4th Int. Conf. on Mechanical Eng., 37–42 (6 pages).

Letters to Editor

GJESM Journal welcomes letters to the editor for the post-publication discussions and corrections which allows debate post publication on its site, through the Letters to Editor. Letters pertaining to manuscript published in GJESM should be sent to the editorial office of GJESM within three months of either online publication or before printed publication, except for critiques of original research. Following points are to be considering before sending the letters (comments) to the editor.

[1] Letters that include statements of statistics, facts, research, or theories should include appropriate references, although more than three are discouraged.
[2] Letters that are personal attacks on an author rather than thoughtful criticism of the author’s ideas will not be considered for publication.
[3] Letters can be no more than 300 words in length.
[4] Letter writers should include a statement at the beginning of the letter stating that it is being submitted either for publication or not.
[5] Anonymous letters will not be considered.
[6] Letter writers must include their city and state of residence or work.
[7] Letters will be edited for clarity and length.