The global disaster COVID-19 pandemic has various reasons for its dramatic increase worldwide. Some researchers opine that the SARS-CoV has its origin from bats and the prevalence of this virus to humans was through palm civets: the intermediate source between bats and human population. 1, 2 The most responsible reasons for it include the large human population gathering and human intervention which have violated the ecosystem globally. The population of the world intrudes the various untouched ecologies and put themselves before the unknown viruses and bacteria without knowing their threat or impact of exposure to humankind. 3, 4 The Coronavirus can travel beyond species boundaries. Earliest infection of SARS-CoV-2 was in Wuhan (China), and the WHO has called this pandemic as Corona Virus Disease 2019 . Initially, it was thought, that this virus also has its origin from the animals to humans, as some of the infected people were from a wholesale seafood market in Wuhan. At a later stage, infections were found in humans, those who have not even visited that particular market. Thus, making clear that this virus can also spread by human to human exposure [5] [6] [7] .
There can be various ways of transmission for this virus to infect the human population. Spreading or transmission of COVID-19 can be through close contact of human beings or by touch or the aerosol spreading of the virus. [8] [9] [10] The most common way of spreading of this virus is through respiratory droplets as the infected one coughs or sneezes. These micro-droplets containing the virus can infect a healthy human by settling on the face (mouth, nose, ears, eyes) or hands 11 . This virus can sustain for a long time on various surfaces which is also considered as a significant reason for its transmission. Frequent touching of the facial area, handshake and unavoidable touch to different surfaces while travelling (through various transport means) is also a significant threat to humans. Also, the transmission is known as "hidden transmission" by the carrier unknowingly spreading the infection to other population exists 12 .
Coronavirus can last on for long durations on different metal surfaces, ranging from hours to days 13, 14 . Recent studies show that the Coronavirus can last about three days on a plastic surface as well as on stainless steel surface, it can also sustain for a period of whole one day on cardboard whereas it can only sustain for about four hours only on a copper surface 15 .
The use of Disinfectants decimates microorganism of virus or bacteria on inner layers or inert surfaces by acting as an antimicrobial agent. Disinfectants are not always impressive against all kinds of microorganism like bacterial spores as sterilisation, which kills all types of life by the use of extreme physical or chemical procedures 16 . Disinfectants play a critical role in decimating microorganisms outside the human body or on various surfaces. It separates disinfectants from antibiotics and antiseptics, which acts inside the human body or on living tissues, respectively. Mechanism of disinfectants involves the destroying of the cell wall of microbes and enters into their metabolism to destroy or inactivate them.
There are many sanitizers available in the market to disinfect different metal surfaces. These were having composed of chemical substances capable of disinfecting microorganisms which may be suspended in various media like air, alcohol and alcohol plus quaternary ammonium cation based compounds, Aldehydes, Oxidizing agents and the biguanide polymer polyaminopropyl biguanide etc. Table 1 shows various disinfectants and their role. 
These are sporicidal and fungicidal and inactivate the organic matter partially.
The mechanism involves the oxidising of the cell membrane, which leads the virus to death or in the activity. Chlorine and oxygen are powerful oxidisers.
These are also very good oxidants and effective in disinfection of viruses and bacteria.
These are the ingredients of disinfectants and found in mouth wash, soap and hand wash.
Quaternary ammonium compounds Also known as "quats" and shows a very high tendency with alcohol to kill viruses like norovirus, rotavirus, or poliovirus, which are non-enveloped.
It has the solution of chlorine, hypochlorite, or hypochlorous acid which is capable of destroying the viruses, bacteria, mycobacteria and the spores. Chlorine is considered as an excellent disinfectant of water, whether it is drinking water, pool water or wastewater 23 .
Sanitizers are the substances that disinfect and clean simultaneously, and these kill more germs than the sanitizers 24,25 . Disinfectants are frequently used in hospitals, clinics, and also in the bathrooms and kitchens to kill infective organisms. From the above table, we can decide the role of disinfectants in human life.
A comparative study of SARS-CoV-2 and SARS-CoV-1 viruses is done to estimate their decay rate on different metal surfaces and in an aerosol. They have used a Bayesian regression model to study the decay rate of the virus on different surfaces. Around ten experiments with different conditions involving the above two viruses were done for five different environmental conditions. These include four metal surfaces and aerosol. Plastic, Stainless Steel, Copper, and Cardboard were the four metal surfaces taken to consideration. The reason behind to take theses metal surfaces was the use of these materials in our day to day life, whether the population is travelling, shopping or doing work in the office. Study on the aerosol showed that SARS-CoV-2 could sustain it for up to three hours. One important observation was that during the time the virus reduces its infecting capability, from 103.5 to 102.7 Tissue Culture Infective Dose (TCID) 50 per litre of air. A similar tendency of SARS-CoV-1 is also observed in this study and identified that the infection capability of COVID-19 virus has reduced from 104.3 to 103.5 TCID50 per millilitre 26 . Table 2 gives a comparative study of both viruses and shows that SARS-CoV-2 and SARS-CoV-1 have significant sustaining time on different surfaces. Although the behaviour of both the viruses is almost similar on some metal surfaces like in the first three environmental conditions, they show linear decay in infection capability [27] [28] [29] [30] . However, in aerosol, plastic and stainless steel, the concentration of virus on the medium is different, but the differences are insignificant. Under the tested experimental conditions, SARS-CoV-2 was similar to SARS-CoV-1. These viruses include high viral load having the potential to infect the peoples, and before spreading, the affected person may be asymptomatic [31] [32] [33] [34] [35] .
From the available data, an analysis is made on the infection capability and duration for which a particular virus can sustain in a medium or on a surface to depict the trend of decreasing infection tendency of the virus ( figure 1 and 2) . Thus, to make these two graphs, the lower concentration values were taken from the table no. 1, as those are the correct values of concentration at the end of sustaining time of virus on different metal surfaces. It can be derived from Figure 1 and Figure 2 , that, the sustainability of SARS-CoV-2 is more or less similar to SARS-CoV-1 for the given environmental conditions. We see a linear decrease in the infection capability of this virus, with respect to time, and the same varies according to the medium (surface). This linear decrease shows the exponential decay in virus titre in per litre of air or millilitre of medium with time. The green line shows the linear decay of infection capability in the graphs. Graphs for both SARS-CoV-2 and SARS-CoV-1 are confined from 1 to Stainless Steel, 4-Copper and 5-Cardboard.
Coronavirus can sustain for a long time on various surfaces which is a major reason for its transmission. This virus can contaminate on different metal surfaces and stay on them from hours to days, with a maximum span on plastic and stainless and least on the copper surface. The alcohol-based disinfectants can significantly reduce the survival and decay time of the virus. The two important Coronaviruses (SARS-CoV-2 and SARS-CoV-1) have significant sustaining time on different metal surfaces, and their behaviour is almost similar on various metal surfaces and in aerosols.