Effect of COVID-19 pandemic-induced lockdown (general holiday) on air quality of Dhaka City.

A worldwide pandemic of COVID-19 has forced the Government of Bangladesh to implement a lockdown during April-May 2020 by restricting people's movement; shutdown of industries and motor vehicles; and closing markets, public places, and schools to contain the virus. This type of strict measures caused an outcome, the reduction of urban air pollution, around the world. The present study aims to investigate the reduction of the concentration of pollutants in the air of Dhaka City and the reduction of the Air Quality Index (AQI). Necessary time-series data of the concentration of PM2.5, NO2, SO2, and CO have been collected from the archive of the Air Quality Monitoring Station of the US Embassy in Dhaka and Sentinel-5P. The time-series data have been analyzed by descriptive statistics, and AQI was calculated following an appropriate formula suggested by the Environmental Protection Agency (EPA) based on the criteria pollutants. The study found that the concentrations of PM2.5, NO2, SO2, and CO during April-May 2020 have been reduced by 26, 30, 07, and 07%, respectively, compared with the preceding year's concentrations. Moreover, the AQI has also been reduced by about 35% on average during the lockdown period than the same times of the previous year. However, the magnitude of pollution reduction in Dhaka is lower than in other cities and countries globally, including Delhi, Sao Paulo, Wuhan, Spain, Italy, the USA. The main reasons may include, among others, the poor implementation of lockdown (especially in the first week of April and the second fortnight of May), pre-existing pollution, transboundary pollution, incineration of solid waste, etc. This study will help policymakers figure out how to regulate pollution sources and improve the air quality of Dhaka.

Maternal vitamin D3 supplementation during the third trimester of pregnancy: effects on infant growth in a longitudinal follow-up study in Bangladesh.

OBJECTIVE: To estimate the effects of prenatal vitamin D supplementation on infant growth in Dhaka, Bangladesh. STUDY DESIGN: Longitudinal follow-up of infants born at term or late preterm (≥34 weeks) to participants in a randomized double-blind trial of maternal third-trimester vitamin D3 (35 000 IU/wk; vitamin D ) vs placebo. Anthropometry was performed at birth, 1, 2, 4, 6, 9, and 12 months of age. The primary analysis (n = 145 overall; n = 134 at 1 year) was a comparison of mean length-for-age z-score (LAZ) based on World Health Organization standards. RESULTS: LAZ was similar between groups at birth, but 0.44 (95% CI, 0.06-0.82) higher in vitamin D vs placebo at 1 year, corresponding to a sex-adjusted increase of 1.1 cm (95% CI, 0.06-2.0). Mean change in LAZ from birth to 1 month was significantly greater in vitamin D (0.53 per month) vs placebo (0.19 per month; P = .004); but there was no significant divergence thereafter. In longitudinal (repeated-measures) analysis, average LAZ during infancy was 0.41 higher in vitamin D vs placebo (95% CI, 0.11-0.71, P = .01). Stunting was less common in vitamin D (17% of infants were ever stunted) vs placebo (31%; P = .049). Other anthropometric indices were similar between groups. CONCLUSIONS: Maternal vitamin D3 supplementation (35 000 IU/wk) during the third trimester of pregnancy enhanced early postnatal linear growth in a cohort of infants in Bangladesh.