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Introduction COVID-19 is a pandemic that affected humans’ lives and activities through the year 2020 in a way that was not witnessed in recent years. Many governments declared a complete lockdown as a try to stop the transmission of the disease. This lockdown resulted in a good recovery in environmental health, where air pollutants levels dramatically decreased. Theory There are two relations between air pollution and COVID-19, one is before the disease spread, and the other is after. Before the disease spread, many areas had high levels of contaminants in the air due to industrial activities, transportation, and human density. These areas had the highest infection rates and death cases. This could be attributed to two reasons, the aerosol could help to spread the virus at a higher rate, and air pollutants could negatively affect peoples’ lungs, which assisted the virus in attacking the patients brutally. Results After the disease spread, the lockdown that was applied in the major industrial countries led to a decrease in the pollutants levels and an increase in the ozone level in the air. This lockdown improved the air quality worldwide to a level that all political conferences and agreements could not reach. In this review, we are showing the impact of COVID-19 on air pollutants in different countries. Summary This paper provides information about pollutants' influence on human and environmental health that other researchers obtained in different areas of the globe before and after the pandemic. This could give ideas about the impact of humans on the environment and the possible ways of recovering the environment's health.

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Abstract. The forward osmosis (FO) process has been considered to be a viable option for water desalination in comparison to the traditional processes like reverse osmosis, regarding energy consumption and economical operation. In this work, a polyacrylonitrile (PAN) nanofiber support layer was prepared using the electrospinning process as a modern method. Then, an interfacial polymerization reaction between m-phenylenediamine (MPD) and trimesoyl chloride (TMC) was carried out to generate a polyamide selective thin-film composite (TFC) membrane on the support layer. The TFC membrane was tested in FO mode (feed solution facing the active layer) using the standard methodology and compared to a commercially available cellulose triacetate membrane (CTA). The synthesized membrane showed a high performance in terms of water flux (16 Lm −2 h−1) but traded the salt rejection (4 gm−2 h−1) compared with the commercial CTA membrane (water flux = 13 Lm−2 h−1 and salt rejection = 3 gm−2 h−1) at no applied pressure and room temperature. Scanning electron microscopy (SEM), contact angle, mechanical properties, porosity, and performance characterizations were conducted to examine the membrane.

Reverse osmosis is a major process that produces soft water from saline water, and its output represents the majority of the overall desalination plants production. Developing efficient membranes for this process is the aim of many research groups and companies. In this work, we studied the effect of adding cellulose micro crystals (CMCs) and cellulose nano crystals (CNCs) to the support layer and thin film nanocomposite (TFN) membrane on the desalination performance. SEM, TEM, ATR-FTIR, and contact angle measurements were used to characterize the membrane’s properties; and membrane’s performance were evaluated by water flux and NaCl rejection. Filling 2% of CNCs gel in the support layer improved the water flux by +40%, while salt rejection maintained almost the same, around 95%. However, no remarkable improvement was gained by adding CNCs gel to m-phenylenediamine (MPD) solution, which was used in TFN membrane preparation. Filling CMCs powder in TFN membrane led to a slight improvement in terms of water flux.