Risk assessment of corona virus: Implementing hierarchy of hazard control in workplaces

The novel coronavirus or the other name Severe Acute Respiratory Syndrome coronavirus-2 (SARS-CoV-2), was fi rst identifi ed in Wuhan, China, in December 2019 among a group of patients that have the same symtoms of viral pneumonia. Due to the socio-economic factors in Zhuhai, Wuhan and globalization have also accelerated the spread of infectious diseases to the other parts of China and the world [1,2], The World Health Organisation (WHO) declared Covid-19 a public health emergency of international concern as of 1 February 2020 and epidemic as pandemic on 12 March 2020. The virus spreads very rapidly and globally, as of 25 February 2021, there have been more than 113 million confi rmed cases of Covid-19, including more than 2.5 million deaths, reported to WHO. Although initation of vaccination have raised hopes of bringing the pandemic under control, the recent news about the mutated variant of the novel coronavirus associated with recent infections make governments and people concerned about the future. WHO is warning that back to old normals is likely to take a long time, possibly several years due to the time required to manufacture and distribute millions of doses of vaccine.


Introduction
The novel coronavirus or the other name Severe Acute that have many similarities [3]. However, the origin of the novel SARS-CoV-2 is unclear so far while the causative agents

Mini Review
Risk assessment of corona virus: Implementing hierarchy of hazard control in workplaces not infected. The economic impact would take a hit in Gross Domestic Product (GDP) ranging from 3-6% depending on the country in a mild scenario; in severe scenarios, it is more than 10%, and in some countries, more than 15% [11] and global economic losses of the Covid-19 outbreak is estimated to reach up to $8.8 trillion [12].  [13,14] compatible with the US National Institute for Occupational Safety and Health (NIOSH) hierarchy of hazard controls [15]. These strategies focuses on three main measures for prevention: wearing mask, maintaining social distancing of at least 2 metres and frequent and thorough hand-washing [16].
Covid-19 can be brought under control by taking effective measures in the workplaces along with the measures to be taken on the society [17]. The objective of this study is to provide considerable expertise in the occupational hygiene and exposure science and professional communities that can contribute helping employers and workers to contain and delay the spread of Covid-19.

Exposure assessment
The major route of transmission of Covid-19 is droplet, close contact and touching surfaces contaminated by them and then touching nose, mouth and eyes [18]. The virus can remain viable for two/three days on plastic and metallic surfaces [19].
Droplet spread was detected over 6-8 m and coronavirus could spread beyond 1-2 m in a concentrated packet through coughs or sneezes [20] and the risk of corona virus transmission at 1 m could be 2-10 times higher than at 2 m [21]. However, infection transmission with contaminated water, stools, with subsequent feco-oral route have also been reported [19,22]. Infection is transmitted by symptomatic patients but can also occur from asymptomatic people also before onset of symptoms [23].
Long incubation time before onset of symptoms is the greatest challange to prevent spread. Based on work activities contagion can be lower or higher depending on several factors: e.g. work sector; need for close contact or need for repeated or extended contact with people known to be or suspected of being infected [24]. Therefore, OSHA has divided job tasks into four risk exposure levels from very high to lower risk group and the most workers in the world will likely fall in the lower exposure risk or medium exposure risk levels [14].

Risk management
Elimination and substitution are the best ways to mitigate the risks [25] therefore many companies have started working from home as a temporary or alternative working arrangement.
However the International Labour Organisation (ILO) estimates that close to 18 per cent of workers have occupations that are suitable for working from home [26].
Engineering controls are the second option to reduce the hazard/risk at source without relaying to worker behavior.
Structural measures like simple screens and barriers may offer some degree of protection from Covid-19 compared to the more open interactive style of work [27]. Although, the viral particles are too small to be contained by even the best High Effi ciency Particulate Arresting (HEPA) and Minimum Effi ciency Reporting Value (MERV) fi lters, proper fi lter installation and maintenance can help to reduce the risk of airborne transmission [28]. Additionally, higher outside air fractions and higher air exchange rates in workplaces may help to dilute the indoor contaminants, including viral particles, from air that is breathed within buildings.
Administrative controls limit exposure by scheduling shorter work times in contaminated areas or by implementing other "rules". Implementation of the hygiene rules with providing hand sanitizer, disinfecting wipes, facial tissues, and with simple instructions to employees to alter behavior was shown to signifi cantly reduce the phage on fomites and hands [29].
Frequent cleaning of surfaces with proper cleaning agents [30] and disinfection of hands with alcohol based sanitizers can reduce the transmission of pathogenic agents [31,32] at a greater of phage concentrations of 85.4% [33]. However, sanitizers are volatile chemicals and the effects are relatively short lived due to evaporation, so the best defense for to stop transmission of virus is to ensure public health hygiene and sanitation interventions, such as the use of soap, hand sanitizers, surface disinfectants, and behavior modifi cation [29,34]. More persistent surface cleaning treatments, the use of nanomaterials such as nano-silver, may be used to reduce surface viral load [35]. Nanoparticle treated air fi lters can also reduce the airborne virus concentration [36]. Nevertheless, disinfection procedures of equipments in hospitals and wards must be provided in high attention against patients in isolation precautions because of higher bacterial loads and a potential higher CFU load [37,38]. Since behavior change is diffi cult and requires sustained motivation and support, nevertheless most efforts to change behaviours have had limited success [39], training is crucial for employees' support for of any safety plan. Employees must be trained about Covid-19, transmission routes, prevention methods, hygiene rules, social distancing techniques and PPE.
As WHO and other institutions have recommended, wearing proper mask or PPE is one of the major defence to coronavirus [16]. Face mask use could result in a large reduction in risk of infection, with stronger associations with N95 or similar respirators compared with disposable surgical masks or similar [40]. However, using PPE must not take the place of primary prevention interventions.

Conclusion
Corona virus is a biological hazard that no one knows when pandemic will end. Therefore we all have to learn to live with pandemic by transforming our behaviors, habits, houses, schools and workplaces according to the "new normals" based on reducing the infection risk. The major of the society is not yet infected and OHS measures to be taken at workplaces will prevent the occurrence of next waves of the pandemic and ensures the increase of cases in acceptable limits.
In order to minimize the health risk of coronavirus in workplaces, OHS specialists should make appropriate recommendations for all employees. Despite the lack of knowledge about coronavirus and experience in managing pandemic, risk assessment process should based on the principles for determining appropriate risk management steps to reduce transmission in the workplace, facilitating business continuity, and advancing worker well-being. In order to minimize the effects of both current and future outbreaks, risk management process should include on an integrative approach that combines the best available scientifi c data with psychosocial and community factors.