Current World Environment

Dear Readers,

Hope you are safe and doing well.

I am pleased to present before you this issue of Current World Environment. In spite of tremendous pressure due to second wave of COVID-19, the authors, editors and the staff of journal office have shown their great cooperation to bring out this issue in time. I thank all the contributors for their dedication for making the successful release of this issue.

The COVID-19 shutdown has been a major challenge for mankind. This pandemic period has witnessed relatively clean environment especially very significant reduction in air pollution and haze levels due to closure of fossil fuel driven industries, automobiles and aviation. According to a study the South Asian region experienced around 50% reduction in in NO₂ concentrations¹. The major sources of NO₂ include combustion of coal, petrol and diesel. The pandemic lockdown has taught us a lesson of `new normals’². The shutdown period air pollution levels have verified the IPCC findings confirming that the present era climate change is due to anthropogenic activities³. The reduction in pollution during shutdown has open a new path for sustainable development using clean energy alternates⁴.

The COVID-19 origin and spread pathways had a number of theories. In the beginning of lockdown last year, the public was on crossroads having huge confusion what to do what not to do? Slowly, the situation became clear and directional with help of World Health Organization (WHO) and other organizations. The World Health Organisation (WHO) declared the COVID-19 as a pandemic. There were doubts whether the COVID-19 is spreading through air? Soon, the researchers established its airborne presence and transmission routes^5-6. A number of quick studies on COVID-19 strengthened our understanding about its spread^6-10. According to studies, possibility of airborne transmission of COVID-19 are high in the dry air (below 40% RH)^5,8. Based on an indoor experiment from Chinese cities during Jan-March 2020, it was found that less than 40% RH activates the evaporation of water in the cough droplets, leading to droplet shrinkage and prolonged suspension in air whereas high RH at 95% will increase the droplet size due to hygroscopic growth with higher deposition fractions both on humans and on ground.

Exposure to aerosol virus is equally possible as via larger respiratory droplets or direct contact with infected people or contaminated surfaces¹¹. The transmission of SARS-CoV-2 is much higher indoors than outdoors¹². However, more comparative studies are needed to estimate the indoor impact vis-e-vis modular buildings and Indian style ventilated houses. The in-situ study on risk assessment due to airborne transmission of COVID-19 viruses generated by asymptomatic individuals in a confined space under ventilation has shown 10% increase in risk¹³. In an apartment building in Seoul, South Korea, an epidemiological relationship study involving COVID-19 infected cases demonstrated the spread of virus to upstairs and downstairs through the air duct¹⁴.

In a nutshell, though in the beginning of pandemic, spread of COVID-19 was widely recognized via larger respiratory droplets or direct contact with infected objects. But recent research confirms that it can be transmitted through inhalation of airborne viruses. However, more epidemiological studies are needed to understand the impact of air pollution on COVID-19. Similarly, more comprehensive In vitro and in vivo studies are needed to understand air particle–virus interactions¹⁰. Since, at present it is established that the COVID-19 spread is possible through inhalation, there is a need to avoid crowdedness at various places such as market, offices, hospitals and other common places. Isolation of infected person will further help in controlling the spread of viruses. Bearing mask will also reduce the possibility of infection through inhalation. Of course, everyone needs to vaccination too.  In addition, there is a need to establish a global network for monitoring of infectious aerosols.

References
 

1. Mishra M. and Kulshrestha U.C. 2021. A Brief Review on Changes in Air Pollution Scenario over South Asia during COVID-19 Lockdown. Aerosol and Air Quality Research, 21, doi.org/10.4209/aaqr.200541.
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2. Kulshrestha U.C. 2020. New Normal’ of COVID-19: Need of New Environmental Standards., Current World Environment, https://www.cwejournal.org/vol15no2/new-normal--of-covid-19--need-of-new-environmental-standards/.
   CrossRef
3. IPCC. 2013. IPCC confirms that human activity will further warm the Earth, with dramatic effects on weather, sea-levels and the Arctic. https://www.unep.org/news-and-stories/press-release/ipcc-confirms-human-activity-will-further-warm-earth-dramatic. Retrieved on April 22, 2021.
4. Kulshrestha U. 2020. Impacts of COVID-19 on Air Pollution and Strategies for Improvement. In COVID-19 & National Lock Down: Impacts & Future Strategies in Agriculture & Environment, Technical Bulletin, Society or Conservation of Nature (SCON), New Delhi, August Special Issue, pp 13-15.
5. Yao M., Zhang L., Ma J., & Zhou L. 2020. On airborne transmission and control of SARS-Cov-2. Science of The Total Environment, 731, 139178.
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6. Hadei M., HopkeP.K., Jonidi, A. and Shahsavani A. 2020. A Letter about the Airborne Transmission of SARS-CoV-2 Based on the Current Evidence. Aerosol Air Qual. Res. 20:911-914. https://doi.org/10.4209/aaqr.2020.04.0158.
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7. Ahlawat A., Wiedensohler A., and Mishra S. K. 2020. An Overview on the role of relative humidity in airborne transmission of SARS-CoV-2 in indoor environments. Aerosol and Air Quality Research, 20(9), 1856-1861.
8. Feng Y., Marchal T., Sperry T., & Yi H. 2020. Influence of wind and relative humidity on the social distancing effectiveness to prevent COVID-19 airborne transmission: A numerical study. Journal of aerosol science, 147, 105585.
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9. Mutuku J.K., Hou W.C. and Chen W.H. 2020. An Overview of Experiments and Numerical Simulations on Airflow and Aerosols Deposition in Human Airways and the Role of Bioaerosol Motion in COVID-19 Transmission. Aerosol Air Qual. Res. 20: 1172–1196. https://doi.org/10.4209/aaqr.2020.04.0185.
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10. Bourdrel T., Annesi-Maesano I., Alahmad B., Maesano C. N., Bind M. 2021. The impact of outdoor air pollution on COVID-19: a review of evidence from in vitro, animal, and human studies. European Respiratory Review, 30: 200242; DOI: 10.1183/16000617.0242-2020.
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11. Tang, J. W., Bahnfleth, W. P., Bluyssen, P. M., Buonanno, G., Jimenez, J. L., Kurnitski, J. et al. Dismantling myths on the airborne transmission of severe acute respiratory syndrome coronavirus (SARS-CoV-2). Journal of Hospital Infection.
12. Greenhalgh T., Jimenez J. L., Prather K.A., Tufekci Z., Fisman D., Schooley R. 2021. Ten scientific reasons in support of airborne transmission of SARS-CoV-2. The Lancet, doi.org/10.1016/S0140-6736(21)00869-2.
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13. Shao S., Zhou D., He, R., Li J., Zou S., Mallery K., ... and Hong J. 2021. Risk assessment of airborne transmission of COVID-19 by asymptomatic individuals under different practical settings. Journal of aerosol science, 151, 105661.
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14. Hwang S. E., Chang J. H., Oh B., and Heo J. 2021. Possible aerosol transmission of COVID-19 associated with an outbreak in an apartment in Seoul, South Korea, 2020. International Journal of Infectious Diseases, 104, 73-76.
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