The role of the environment and its pollution in the prevalence of COVID-19
Authors: Hasti Daraei, Kimia Toolabian, Marzieh Kazempour, Mohammad Javanbakht
Journal: Journal of Infection (2020)

Coronaviruses are a large group of viruses that can infect animals and humans and cause severe respiratory disease. In December 2019, for the first time in Wuhan, Hubei Province, China, Coronavirus was detected in humans. As of May 12, the new coronavirus has infected more than 4256,076 people worldwide.1Fox D. What you need to know about the Wuhan coronavirus.Nature. 2020; Crossref Google Scholar COVID-19 is a virus with a high transmission rate that can be transmitted through direct contact (person to person) and indirect contact (contact with virus-infected surfaces).2Casanova L. Rutala W.A. Weber D.J. Sobsey M.D. Survival of surrogate coronaviruses in water.Water Res. 2009; 43: 1893-1898Crossref PubMed Scopus (286) Google Scholar Because to date, many efforts have been made to reduce direct contacts (person to person) and personal hygiene, unfortunately, we are still seeing the prevalence of this disease worldwide. Now this question arises, why still in some regions the COVID-19transfer speed is greater despite the implementation of a social distance plan? Thus, this hypothesis is formed that indirect exposure may also play a significant role in the transmission of COVID-19.The environment around us is fraught with contaminants and surfaces that can unintentionally expose the human to the virus. Therefore, to investigate the prevalence of coronavirus, it should be more attentive to environmental pollutants. Environmental pollutants that may play a significant role in the COVID-19 spread include air pollutants, sewage, polluted water, and waste, which their role in the indirect expansion of the virus should be considered. The air is the main environment we deal with and inhale it every day with all its pollutants. The most important pollutants are NOx, SOx, O3, PM2.5 and CO, which are mainly due to traffic and vehicles.3Travaglio M., Yu Y., Popovic R., Leal N.S., Martins L.M.Links between air pollution and COVID-19 in England. medRxiv. 2020:2020.04.16.20067405.Google Scholar Studies have proven that these pollutants are able to reduce the level of immune system and therefore make the body weak against various viruses and pathogens.4Wu X., Nethery R.C., Sabath B.M., Braun D., Dominici F.Exposure to air pollution and COVID-19 mortality in the United States: a nationwide cross-sectional study. medRxiv. 2020:2020.04.05.20054502.Google Scholar With knowledge of this subject, this hypothesis formed that air pollution can have a synergistic effect on coronavirus performance. Conticini et al. 2020 reported a significant association between coronavirus transmission and air pollution in some parts of Italy.5Conticini E. Frediani B. Caro D. Can atmospheric pollution be considered a co-factor in extremely high level of SARS-CoV-2 lethality in Northern Italy?.Environ Pollut. 2020; 261114465Crossref PubMed Scopus (642) Google Scholar Travaglio et al. 2020 reported that in regions of Britain with high NOx levels, the deaths associated with the COVID-19 were higher.3Travaglio M., Yu Y., Popovic R., Leal N.S., Martins L.M.Links between air pollution and COVID-19 in England. medRxiv. 2020:2020.04.16.20067405.Google Scholar A study in the United States found a significant link between air pollution and coronavirus mortality, so with the increase of 1 µg/m3 of PM, the COVID-19-related mortality rises to 15%.4Wu X., Nethery R.C., Sabath B.M., Braun D., Dominici F.Exposure to air pollution and COVID-19 mortality in the United States: a nationwide cross-sectional study. medRxiv. 2020:2020.04.05.20054502.Google Scholar Air pollutants can cause coronavirus in many different ways. Some studies stated that the body in normal condition produces a small amount of nitrogen oxide that is able to prevent the process of duplicating the RVS in the lungs. In contrast, during air pollution, when NOx rises in the environment and inhaled by the individual, it suppresses the production of endogenous nitric oxide and increases RVS production. Nitrogen is also a free radical in the body, which can act as a lung stimulant. Then NOx can reduce lung activity and increase infection in the airway.6Shan J. Ni Y. Dong W. Xu J.H. Pan L. Li H.Y. et al.[The effect of short-term exposure to ambient NO(2) on lung function and fractional exhaled nitric oxide in 33 chronic obstructive pulmonary disease patients].Zhonghua Yu Fang Yi Xue Za Zhi. 2017; 51: 527-532PubMed Google Scholar Ozone, another air pollutant, can also stimulate the respiratory system and decrease the lung function by producing other oxidant products.7Zhang J. Wei Y. Fang Z. Ozone pollution: a major health hazard worldwide.Front Immunol. 2019; 10: 2518Crossref PubMed Scopus (343) Google Scholar Since O3 and SOx have significant impacts on TNF, 1tumor necrosis factor IL 2interleukin1 b, IL-6, IL-8, IL-17 and IL-18, they have a prominent role in inflammation of the respiratory and systemic systems, thus increasing the risk of developing coronavirus.8Che L. Jin Y. Zhang C. Lai T. Zhou H. Xia L. et al.Ozone-induced IL-17A and neutrophilic airway inflammation is orchestrated by the caspase-1-IL-1 cascade.Sci Rep. 2016; 6: 18680Crossref PubMed Scopus (31) Google Scholar,9Kurai J. Onuma K. Sano H. Okada F. Watanabe M. Ozone augments interleukin-8 production induced by ambient particulate matter.Genes Environ. 2018; 40: 14Crossref PubMed Scopus (13) Google Scholar PM10 and PM2.5 are of other air pollutants. There is a hypothesis that these particles can act as a carrier to transmit and disperse coronavirus in the air. Researchers demonstrated that coronavirus can survive on PM about 3 h.10van Doremalen N., Bushmaker T., Morris D., Holbrook M., Gamble A., Williamson B., et al. Aerosol and surface stability of HCoV-19 (SARS-CoV-2) compared to SARS-CoV-1. medRxiv. 2020:2020.03.09.20033217.Google Scholar On the other hand, PM10/2.5 by penetrating the depth of lung not only can paralyzes the ciliums airway, but also lead to chronic respiratory tract inflammation.Therefore, the chances of contracting the coronavirus increase in air containing high particulate matter concentrations.11Frontera A. Martin C. Vlachos K. Sgubin G. Regional air pollution persistence links to COVID-19 infection zoning.J Infect. 2020; Abstract Full Text Full Text PDF PubMed Scopus (118) Google Scholar PM10/2.5,due to their very small size, easily penetrate to the lower respiratory tract, and as a result, they can carry the coronavirus directly into the alveo and tracheobrochial region.12Qu G. Li X. Hu L. Jiang G. An imperative need for research on the role of environmental factors in transmission of novel Coronavirus (COVID-19).Environ Sci Technol. 2020; 54: 3730-3732Crossref PubMed Scopus (222) Google Scholar Another possible way to transmit the virus may be to sewer systems. The urine and stool of the patient can enter the virus into the sewer network and cause it to release. Weber et al. 2016 explained that the Severe Acute Respiratory Syndrome-CoV could stay viable for about 4 h in the stool.13Weber D.J. Rutala W.A. Fischer W.A. Kanamori H. Sickbert-Bennett E.E. Emerging infectious diseases: focus on infection control issues for novel coronaviruses (Severe Acute Respiratory Syndrome-CoV and Middle East Respiratory Syndrome-CoV), hemorrhagic fever viruses (Lassa and Ebola), and highly pathogenic avian influenza viruses, A(H5N1) and A(H7N9).Am J Infect Control. 2016; 44: e91-e100Abstract Full Text Full Text PDF PubMed Scopus (84) Google Scholar Tang et al. 2020 reported that the coronavirus could survive 9 days in the fecal and sewer.14Tang A. Tong Z.-.D. Wang H.-.L. Dai Y.-.X. Li K.-.F. Liu J.-.N. et al.Detection of Novel Coronavirus by RT-PCR in stool specimen from asymptomatic child, China.Emerg Infect Dis. 2020; 26Crossref Scopus (24) Google Scholar Thus, with knowledge of this issue, during the toilet flushing, urinary and fecal aerosols can carry the virus and infect the ambient air. If personal hygiene is not good, the situation will get worse.15Peiris J.S.M. Chu C.M. Cheng V.C.C. Chan K.S. Hung I.F.N. Poon L.L.M. et al.Clinical progression and viral load in a community outbreak of coronavirus-associated SARS pneumonia: a prospective study.Lancet. 2003; 361: 1767-1772Abstract Full Text Full Text PDF PubMed Scopus (1983) Google Scholar The best idea is for patients with positive COVID-19 to use a separate toilet. Due to the survival of the virus in the wastewater, untreated wastewater spray is not recommended for irrigation. Another suspicious source of virus transmission is water resources. Fortunately, to date, there is no evidence that the COVID-19 could survive in surface or groundwater for a long time. Also, the COVID-19 has also not been found in drinking water, because it is rapidly inactivated into chlorinated water.2Casanova L. Rutala W.A. Weber D.J. Sobsey M.D. Survival of surrogate coronaviruses in water.Water Res. 2009; 43: 1893-1898Crossref PubMed Scopus (286) Google Scholar Other studies have shown that the virus can survive in chlorinated waters for two days, while in water contaminated with feces and urine, its survival has been reported for several weeks.2Casanova L. Rutala W.A. Weber D.J. Sobsey M.D. Survival of surrogate coronaviruses in water.Water Res. 2009; 43: 1893-1898Crossref PubMed Scopus (286) Google Scholar Relying on this object, protecting the water distribution systems and by and ensuring don't breakage of water distribution pipes can prevent the outbreak of COVID-19. To date, there is no evidence that waste transmits the COVID-19 to human. But people who come in contact with hospital waste should use personal protective equipment.