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In Bangladesh, a nationwide lockdown was imposed on 26 March 2020, due to the COVID-19 pandemic. Due to restricted emissions, it was hypothesized that the air quality has been improved during lockdown throughout the country. The study is intended to assess the impact of nationwide lockdown measures on air quality in Bangladesh. We analyzed satellite data for four different air pollutants (NO 2 , SO 2 , CO, and O 3) to assess the changes in the atmospheric concentrations of pollutants in major cities as well as across the country. In this study, the concentrations of NO 2 , SO 2 , CO, and O 3 from 1 February to 30 May of the year 2019 and 2020 were analyzed. The average SO 2 and NO 2 concentrations were decreased by 43 and 40%, respectively, while tropospheric O 3 were found to be increased with a maximum of > 7%. Among the major cities, Dhaka, Gazipur, Chattogram, and Narayanganj were found to be more influenced by the restricted emissions. In Dhaka, NO 2 and SO 2 concentrations were decreased approximately by 69 and 67%, respectively. Our analysis reveals that NO 2 concentrations are highly correlated with the regional COVID-19 cases (r = 0.74). The study concludes that the lockdown measures significantly reduced air pollution because of reduced vehicular and industrial emissions in Bangladesh.

The common aspects and processes influencing dissipation kinetics of pesticides are determinants of their fate in the environment. Nowadays, with increasing population, the demand for food and fodder crops has also increased. With the development in science and technology, the methods of controlling pests may improve, but the major role played by the environment cannot be altered, i.e. the environmental factors, climatic conditions, and geology of areas under cultivation. Plants play a crucial role in the dissipation kinetics, as they may vary in species and characteristics. Differences in physico-chemical properties, such as formulation, bioavailability, and efficacy of the pesticide, may result in variable dissipation patterns even under the same environmental conditions. While modelling the dissipation kinetics for any specific pesticide applied to any specific crop, each factor must be considered. This review focusses on the variability observed across common factors, i.e. environmental aspects, plant-associated facts, and observed characteristics of chemical substances, influencing pesticide dissipation.

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