Urban health, safety and environment (HSE)
M.T. Islam; M. Islam; A.A. Nayeem; A.K. Majumder
Abstract
BACKGROUND AND OBJECTIVES: Air pollution and its associated health impacts have become a major concern worldwide, particularly in developing countries. Anthropogenic activities were significantly reduced during the COVID-19 pandemic, allowing for the opportunity for source reduction of air pollutants. ...
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BACKGROUND AND OBJECTIVES: Air pollution and its associated health impacts have become a major concern worldwide, particularly in developing countries. Anthropogenic activities were significantly reduced during the COVID-19 pandemic, allowing for the opportunity for source reduction of air pollutants. A number of studies have been conducted in Dhaka, but most of them are concentrated on a single ground-monitoring station, making it impossible to draw a comprehensive pollution scenario for the entire city. In contrast, this study evaluated the spatio-temporal changes of urban Particulate Matters (PM) in 70 locations from five different land use categories. Hence, this study investigated the influence of the COVID-19 pandemic on PM1 (aerodynamic diameter ≤1 µm), PM2.5 (aerodynamic diameter ≤2.5 µm) and PM10 (aerodynamic diameter ≤10 µm) concentration during three specific time frames: November 2019 (Pre-lockdown), April 2020 (During lockdown), and November 2020 (Post-lockdown).METHODS: The data were collected through portable air quality meter (AEROQUAL 500) during lockdown (April 2020) and post-lockdown (November 2020) period. Data set of pre-lockdowns (November 2019) was collected from Center for Atmospheric Pollution Studies (CAPS). The Tukey’s Post Hoc Multiple Comparison Test was conducted using Statistical Package for the Social Sciences (SPSSv26) to address the significant changes in air quality between the periods. Additionally, the GIS (Geographical Information System) platform was used to see the spatial and temporal variations of PMs over the city.FINDINGS: The study found that average ground level PM1, PM2.5 and PM10 concentration reduced by 75.1, 75.4, 69.6% and 41.1, 32.6, 29.2% respectively during lockdown compared to pre-lockdown and post-lockdown periods. Moreover, the reduction during lockdown was significant at α=0.05 level. The highest reduction was seen in residential areas from the pre-lockdown to lockdown period, whereas in the lockdown to post-lockdown phase that was found in the industrial areas. Interestingly, the northern part of Dhaka city was less polluted than the southern part in all three studied periods. Besides, the Dhaka city dwellers enjoyed comparatively good quality air in lockdown.CONCLUSION: This study suggested that land use-based source apportionment is required to eliminate the particulate concentration from Dhaka city. Besides, 24 hours continuous data is also important to understand the interaction between particulate concentration and climatic forces. Promoting cleaner transportation options, such as electric vehicles and public transportation is recommended as a means of reducing vehicle emissions. Furthermore, governments could consider implementing emissions regulations, setting limits on emissions, or mandating the use of cleaner fuels and technologies to reduce industrial pollution.
Urban health, safety and environment (HSE)
A.A. Nayeem; A.K. Majumder; W.S. Carter
Volume 5, Issue 3 , July 2020, , Pages 207-216
Abstract
BACKGROUND AND OBJECTIVES: The Bangladesh government declared a general holiday beginning on March 26, 2020 aimed to combat coronavirus (COVID-19) pandemic. The aim of this study was to assess the impacts of the general holiday on air quality in Dhaka city area of Bangladesh. METHODS: Hourly PM2.5 (aerodynamic ...
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BACKGROUND AND OBJECTIVES: The Bangladesh government declared a general holiday beginning on March 26, 2020 aimed to combat coronavirus (COVID-19) pandemic. The aim of this study was to assess the impacts of the general holiday on air quality in Dhaka city area of Bangladesh. METHODS: Hourly PM2.5 (aerodynamic diameter ≤2.5 µm) data was collected from publicly available World's Air Pollution: Real-time Air Quality Index Project from March 1 to May 16 for the five years 2016 to 2020. Tukey Multiple Comparison test was conducted to address the observable level of air quality changes between the years. Additionally, Moderate Resolution Imaging Spectroradiometer using the Aerosol Optical Depth with 550nm wavelength was analyzed during the same time period. FINDING: This Study found that, between April 7 and May 16, the mean daily reading of PM2.5 was less in 2020 when compared to previous years. The mean hourly reported PM2.5 during working hours of 6AM and 8 PM for 2020 was statistically lower (at α= 0.01 level) than all other years 2019, 2018, 2017 and 2016. The mean hourly reported PM2.5 for 2019 was statistically higher (at α = 0.01 level) than all other years 2020, 2018, 2017, and 2016. The Bus Rapid Transit and Mass Rapid Transit Construction in 2019 contributed between 24.2% and 38.6% of the PM2.5 dust during this period. The elimination of diesel bus traffic during working hours in 2020 reduced the dust levels between 15.9% and 36.3% compared to the previous four years. A declining trend of AOD550 values was observed from April 7 to May 16, 2020 compared to previous four years (2016-2019). CONCLUSION: During the general holiday period in Dhaka, the daily and working hour PM2.5 as well as daily Aerosol Optical Depth were reduced compared to previous four years (2016-2019). Government action is recommended to reduce dust created during major construction projects. It is recommended the government authorize the replacement of buses with less polluting vehicles.