Iran Occupational Health

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Background and aims: Over the past year, millions of people around the world have infected with the COVID-19 virus. The SARS-CoV-2 replicate efficiently in the human upper respiratory tract. Infected people produce large amounts of the virus in their upper respiratory tract during an introductory period, which leads to more spread of the virus to other people. The World Health Organization has suggested that acute respiratory syndrome SARS-CoV-2 is transmitted through person-to-person transmission and contact with contaminated surfaces. However, the rapid spread of the disease suggests that other routes, such as airborne transmission, may play a role. Several research studies have been performed to evaluate the possible transmission of the virus through the air. Although some studies have found no evidence of airborne transmission, recent work has confirmed the presence of SARS-CoV-2 even in public places. Past experience and knowledge of the mechanism of similar viruses such as SARS-CoV also support this hypothesis.  During COVID-19 pandemic, while the hospitals can be one of the most important centers in providing health care services, due to the inappropriate air ventilation and purification system, high traffic of people; some of them have been introduced themselves as one of the most high-risk sources of SARS-CoV-2 transmission. The present study aimed to assess the SARS-CoV-2 in the air and surfaces of ICU ward in one of the designated hospitals in Tehran; so that in addition to determining the possibility of inhalation and contact exposure in ICU, which is the main ward for presenting special medical care to patients with severe acute respiratory infections, it aimed to assess a hypothesis of SARS-CoV-2 airborne transmission.
Methods: This cross-sectional experimental study was performed on April 29, 2020 in the Covid-19 ICU ward in one of the designated hospitals, Tehran, Iran. The area of ward was 50 m2 and has seven beds, all of which were occupied at the time of sampling, and five medical staff were involving there. All patients were equipped with oxygen masks and all the staff used all conventional personal protective equipment such as Honeywell-75FFP100NL respirators. On average, surface disinfection was performed three times a day. The general ventilation system included the ceiling diffuser to supply fresh air into the room and wall-mounted exhaust vent and did not use natural ventilation (such as opening the window). It should be noted that the exhaust system didnchr('39')t work well at the time of sampling. This study was carried out in two phases including surface and air sampling. Impinger method was applied to air sampling. Thus, at a distance of 1.5 to 1.8 meters from the ground, the air of the ICU ward was passed through a sampling pump with an flow rate of 1.5 l/min into the porous midget impeller-30 ml containing 15 ml of virus transmission medium (PVTM) for 45 minutes. To reverse the presence of SARS-CoV-2 in air samples, the reverse polymerase chain reaction (RT-PCR) reaction method was used. Sampling of surfaces was done with the help of swabs impregnated with the solution of the Viral Transport Medium from a certain area (25 cm2) from the desired part and putting it inside the vial containing the transfer medium (protein stabilizer, antibiotic and buffer solution). They are also were analyzed by RT-PCR technique. Prior to sampling, all laboratory equipment used was sterilized and autoclaved using a 70% alcohol solution according to the US Centers for Disease Control and Prevention (CDC) protocol. The air sampling was done at a distance of 1.5 to 2 meters from the patientchr('39')s bed. The devices used to measure temperature, humidity and air velocity were multi-purpose anemometer (China BENETE, GM8910,) and air pressure, digital barometer (AIRFLOW, DB2, USA). The mean parameters of weather conditions included: air temperature 24 ° C, humidity 35%, air pressure 1005 mb and air velocity of 0.09 m / s.
 
Results: Of the ten air samples, 6 were positive (60%), with the highest RNA concentrations observed at the point between beds 6 and 7 (3913 copies per ml). Most of the reported negative air samples were from the middle of the ward, which was further away from the patientschr('39') beds. The mean RNA concentration of the virus was obtained 820 ± 2601 copies per milliliter. Also, of ten samples taken from different surfaces of the ward, 4 samples were positive (40%) and the highest concentration (8318 copies per ml) was related to the table next to bed number 3. All positive samples were observed close to the patientchr('39')s bed, and the mean RNA concentration of the virus was 3227 ± 3674 copies per milliliter.
Conclusion: The results of the study indicated that the virus was present in the inhaled air of the ward and its surfaces, especially in areas close to the bed of patients. These findings underscore the airborne transmission of the virus along with other ways of transmission, such as person-to-person contact and contact with contaminated surfaces. Due to the environmental pollution of the studied ICU ward to the SARS-CoV-2 virus, the effective implementation of air isolation methods such as the use of respiratory protection equipment (N95 mask) and powered air-purifying respirator as well as ensuring the correct function of hospital ventilation systems and improving it, is essential for the protection of health care staff. Health care workers need to be continuously monitored and screened from a COVID-19 perspective, and infection prevention and control protocols (IPCs), such as respiratory protection, regular cleaning of the environment, and effective disinfection of areas have been implemented. In the case of the virus, the spread of the disease through both direct methods (drops and person-to-person) as well as indirect contact (contaminated objects and airborne transmission) has almost been proven, which reaffirms the need for precautionary measures regarding airborne isolation against the virus. It  has been suggested that in order to more accurately assess the transmission behavior of the virus, similar studies but longitudinal ones have been done from the admission to discharge of the patients  in different wards of the hospitals, moreover, the role of natural and mechanical ventilation systems more comprehensively examined in the presence of airborne virus.

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Background and aims: Coronaviruses are important pathogens in humans and animals. In late 2019, a new coronavirus was identified as the cause of a group of pneumonia cases in Wuhan, Hubei Province, China. The disease spread rapidly, resulting in epidemics in China and reports of sporadic cases worldwide. In February 2020, the World Health Organization (WHO) identified COVID-19, which stands for Coronavirus 2019. The virus that causes COVID-19 has been identified as the Coronavirus virus, Severe acute respiratory syndrome 2 (SARS-CoV-2), formerly known as 2019-nCoV.
Coronavirus disease 2019 (COVID-19) is a name for the disease, and the virus that causes it is known SARS-CoV-2. The very rapid spread of the COVID-19 in China and in many other countries has caused fear among people across the world. The novel coronavirus outbreak declared a Public Health Emergency of International Concern on 30 January 2020.
Due to the fact that one of the ways of transmitting the coronavirus is through respiration, one of the most important ways to prevent coronavirus is to use personal protective equipment, including masks, so the knowledge around the use of masks by the general public prevention COVID-19 disease transmission is advancing rapidly. Policymakers require guidance on how to use masks and how to use them for people in the community to combat the COVID-19 disease pandemic.
In this article, the relevant literature to inform multiple areas include transmission characteristics of COVID-19 disease, filtering characteristics and efficacy of masks and estimated population impacts of widespread community mask use were synthesized.
Methods: In this descriptive review study was examinesd all articles on mask wear and its effect on the prevention of transmission of pandemic diseases, including COVID-19 and influenza, which were published in Farsi and English. PubMed, Web of Science, Google Scholar, Scopus and Embase databases were used to search for articles, focusing on the use of masks and the prevention of COVID-19 disease, and combining appropriate keywords (Masks, SARS-CoV-2, COVID-19, Influenza, Epidemic, Prevention and Transmission) without restricting the type of study.
Results: Corona virus size ranges from 80 to 160 nanometers, which can help in choosing the appropriate mask and respiratory protection. Anyone who comes in close contact (less than  of two meters away) with a person with respiratory symptoms (such as sneezing, coughing, etc.) is at risk for exposure to potentially infectious respiratory particles. A main route of transmission of COVID-19 disease is likely via small respiratory droplets, and is known to be transmissible from presymptomatic and asymptomatic individuals that come out in talking, coughing or sneezing. The most common droplet size is at least 5 to 10 micrometers. SARS-CoV-2 has a high transmission potential and its transmission rate to individuals is about 2.4. Disease spread was reduced by restrict contacts of infected individuals via physical distancing, contact tracing with appropriate quarantine and reduce the transmission probability percent act by wearing masks in public. The evidence indicates that mask wearing reduces the transmissibility per contact by reducing transmission of infected droplets. Public mask wearing is most effective at stopping spread of the virus when compliance is high.  Therefore, one of the most important ways to prevent the coronavirus is to use personal protective equipment, including masks. The standard masks recommended by reputable organizations are surgical masks and N95 masks. The use of cloth masks is recommended as a last resort, and it has been stated that these types of masks are not part of personal protective equipment. Especially in people who are part of the medical staff and do patient care work. Because of the ability of these masks to protect the person is unknown, and caution should be exercised when using these masks. Ideally, these masks should be used with a protective device that covers the entire front of the face (chin and underneath) and both sides of the face. The N95 mask (American standard; equivalent to FFP2 in Europe) is recommended as a mask for health care workers who perform clinical care for patients with COVID-19 disease. So that if these people use these masks well and according to the instructions, they will not have any problems during the epidemic. In this article, the use of surgical and clean masks by medical staff in medical centers to prevent Rhinovirus infection is recommended and similar studies show that fabric masks have less filtration to the rhinovirus. The results of the above study on the use or non-use of fabric masks in the community cannot be used to control the source of coronavirus, which is a seasonal coronavirus. Another point is that wearing a mask as a source control is largely a cessation of this process, as large droplets become smaller particles suspended in the air that can spread more into the air. Homemade masks have the ability to filter out the normal range of droplets, just as they are effective in blocking droplets and particles, meaning that these masks help keep the droplets from spreading in space. There is no RCT study to evaluate the effect of masks on social transmission during a coronary heart disease. While there is evidence of a flu outbreak, the current global epidemic is a unique challenge. According to a conservative assessment of COVID-19, the initial rate of proliferation is estimated at 2.4. If the mask is used and the efficiency of the mask is 50%, this amount will be reduced to 1.35.The spread of the disease. If the spread of the disease is completely stopped, the initial rate of proliferation will be less than one. As a result, the spread of the disease ends in the community. Wearing a mask may be critical to preventing a second wave of infection in the health care system - more research is needed.
Conclusion: A review of the use of masks in this article showed that proper use of masks at the community level has a significant impact on reducing the rate of disease transmission among people in the community. Non-medical masks use substances that prevent the release of droplets of the required size. Non-medical masks are very effective in reducing the transmission of influenza. The results show that non-medical masks are effective in small trials in blocking coronavirus transmission and in areas and periods when the use of masks was required and widely used; the transmission of the disease has decreased in the community. People are usually infected in the early period after infection, which usually has few or no symptoms during this period. It is also suggested that the general use of cloth masks is more effective than other health strategies, distance and patient diagnosis strategies in reducing the rate of disease transmission. It is suggested that government officials and relevant organizations strongly encourage the use of masks by the public and crowded environments as a requirement to reduce disease transmission. To reduce the transmission of respiratory viral disease, the following interventions should be preferred, preferably in combination:
- Frequent washing with or without side disinfectants
- Create a retainer such as using gloves, clothing and a mask equipped with a filter
- Identify suspicious individuals by isolating possible cases
However, it has been warned that long-term routine administration of some of the evaluated measures may be contagious without the threat of disease.
Health officials need to provide specific guidelines for the production, use and disinfection or reuse of facial masks and to review their distribution on a regular basis so that they do not become deficient.
According to the precautionary principle, the positive effect of wearing a public mask is "scientifically acceptable but unclear." While researchers may logically disagree about the degree of reduction and flexibility of the transfer rate, it seems that the relatively low benefits due to the exponential distribution of the transfer process can be collectively profitable. Models show that wearing public masks is most effective in preventing the spread of the virus when acceptance is high. This is the situation we see with vaccines.Therefore, the use of masks should be done extensively with confidence based on this principle in society. All countries suggest that masking is a low-risk but highly potentially positive action, so that many countries with a high prevalence of the disease have been able to reduce mortality with the widespread use of masks. It is recommended that governments apply the requirements for the use of masks, and that organizations that provide public services, such as public transport providers or stores, apply the rules: "Without masks, no services are provided." These rules should be accompanied by measures to ensure that people have access to masks, possibly without problems in the mechanisms of distribution and storage of masks, and to focus on the benefits of public health. Health officials also need to provide specific guidelines for the production, use and disinfection or reuse of face masks, and review their distribution on a regular basis to avoid deficiencies. Also, clear and applicable guidelines can help increase public acceptance of the use of masks at the community level and reduce communities to the goal of ultimately stopping the spread of COVID-19.