Threat posed by airborne COVID-19 virus at workplaces must be taken seriously - Experts

In fact, the Ministry of Health (MOH) has reported that to date, workplace clusters comprised 53.2 percent or 1,549 of the total number of clusters recorded nationwide.

Local researchers have identified workplaces, especially in enclosed buildings, as having a high risk of being a hive of viral infections, including COVID-19. This is because studies have shown that SARS-CoV-2 - the virus that causes the deadly COVID-19 - can spread through the air.

Even the World Health Organisation has warned about the high risk of COVID-19 transmissions in indoor spaces with poor ventilation systems.

Studies by local researchers have revealed that the COVID-19 virus can remain suspended in the air for up to eight hours in indoor spaces without proper ventilation and can spread as far as six metres in aerosol particles.

One of the studies, conducted over April and May last year by Universiti Kebangsaan Malaysia (UKM) academics and led by Department of Earth Science and Environment senior lecturer Associate Prof Dr Mohd Shahrul Mohd Nadzir, found that enclosed spaces with air-conditioning operations that recycle the same air can facilitate the transmission of the virus in the air via aerosols.

Another study, carried out between August and October 2020 by Universiti Tuanku Abdul Rahman (UTAR) indoor air simulation expert Associate Prof Dr Bernard Saw Lip Huat and Universiti Malaya toxicologist Associate Prof Dr Leo Bey Fen, found that the COVID-19 virus particles can remain in the air for over eight hours which makes it difficult to control transmissions.

"This is why it is very important to have good ventilation... windows at home and in the office should be left open to allow fresh air to flow in. However, in the case of offices and factories situated in enclosed spaces where the windows cannot be opened, the proper maintenance of their air-conditioning and ventilation system is crucial," Mohd Shahrul told Bernama.

He said the probability of triggering a COVID-19 cluster is high in a workplace bereft of good ventilation and a well-maintained air-conditioning system if one of the employees happen to be COVID-19 positive as he/she can spread the virus to others through the air.

The findings of the local researchers concerned, which were published in the international scientific journal Nature Scientific Reports in January this year, need to be viewed seriously due to existing statistics pointing to workplaces as prime COVID-19 hotspots.

With the success of the National COVID-19 Immunisation Programme and Malaysia possibly attaining herd immunity by the end of October, it has become all the more pertinent for employers to look into their buildings' ventilation aspect, as well as the standard operating procedures (SOPs) to prevent COVID-19 transmissions.

Moreover, more employees working from home now are expected to return to their offices when new COVID-19 cases drop in numbers. Despite being fully vaccinated, they can still get infected and also spread the virus to others. There are also bound to be employees who have yet to receive the vaccine and they are at risk of becoming severely ill should the virus infect them.

"According to a study we did at a hospital previously, a nurse who was fully vaccinated was twice tested positive for COVID-19. But her symptoms were mild, unlike the unvaccinated ones who are at risk of getting to category three to five of the disease," said Mohd Shahrul.

He said one of their studies which examined the movement of the COVID-19 virus inside indoor spaces showed that SOPs such as frequent washing of hands and observing physical distancing may not provide adequate protection against respiratory droplet microparticles that carry the virus transmitted by infected individuals.

"Hence, SOPs must go hand in hand with a good ventilation system," he added.

Elaborating on the presence of the COVID-19 virus in the air of enclosed spaces, Mohd Shahrul said it happens when droplets released via coughing, sneezing or talking by a COVID-19 positive person adhere to tiny dust particles, particularly those measuring one micrometre in size.

"In the absence of good ventilation, the virus attached to the tiny particles can remain suspended (in the air) for eight hours. In fact, since the COVID-19 virus particles are finer and less than one micrometre in size, it can remain airborne for over eight hours," he explained.

Meanwhile, UTAR's Saw said his study found that 50 percent of the COVID-19 virus spread within a diameter of one metre in an enclosed area while the other half spread beyond two to six metres.

He said the study revolved around a COVID-19 patient who was placed in a hospital ward that was six metres long and fitted with cassette air-conditioning units that could only recirculate the air within the enclosed space and with no air flowing in from outside.

"Based on our study using computational fluid dynamics, we found that the SARS-CoV-2 virus did not go outside the ward concerned.

"It remained suspended in the air in the ward because there was no flow of fresh air to cleanse the virus," he explained.

Saw also said an individual's risk of infection by airborne transmissions would depend on the amount of virus present in an enclosed building.

"There's no other way... employers must take the issue of indoor air quality more seriously," he said, adding that since most employers use centralised air-conditioners, they must also put in place a system that allows fresh air to flow into the building at regular intervals.

"This is done in China where the air-conditioning system is controlled in such a way that for 30 minutes three times a day, fresh air is allowed into the building to flush out the indoor air. However, not many employers are willing to implement such a system because of the (high) costs involved."

Saw also pointed out there is no point in sanitising the office without maintaining its air-conditioning system regularly because the risk of transmission will rise again if a COVID-19 infected person comes to work two days after the space has been disinfected.

He added that employers can also improve their indoor air quality by using air purifiers that possess the HEPA (high-efficiency particulate absorbing) filter.

Meanwhile, in view of the threat posed by airborne COVID-19 transmissions, the Ministry of Human Resources, through the Department of Occupational Safety and Health, has developed an Indoor Air Quality (IAQ) guide to mitigate the risk.

The IAQ guide's objective is to educate the public on improving air ventilation and indoor air quality at places of work, health facilities, homes and public places so as to reduce the risk of airborne COVID-19 transmissions.

The guide, to be followed in addition to complying with the latest SOPs issued by the National Security Council and other measures to stem the transmission of COVID-19, recommends increasing the ventilation rate, reducing the number of people allowed into a building, keeping the door or windows open, using portable air purifiers and increasing the inflow of fresh air from outside.

Commenting on this, Malaysian Society for Occupational Safety and Health (MSOSH) deputy president 1 Mohamad Aliasman Morshidi said under the Occupational Safety and Health Act (OSHA) 1994, action can be taken against employers who fail to provide safe workplaces. The context of a safe workplace also includes safeguarding indoor air quality.

"In general, this Act has several provisions, such as Section 15 and Section 17, outlining the obligations of the employer in ensuring a safe working environment, which is also free of health risks, for their workers.

"As such, employers must prove that they have taken the right step to reduce COVID-19 transmissions in the workplace by conducting proper risk assessment and putting in place effective preventive measures based on the SOPs set by the authorities," he said.

Mohamad Aliasman said if the employer or building owner fails to abide by the IAQ or Industry Code of Practice on Indoor Air Quality 2010, they can be prosecuted under OSHA.

As an association actively involved in matters related to the health and safety of workers in Malaysia, MSOSH conducts various programmes to raise awareness on the importance of ensuring that indoor workplaces have good air circulation systems, he said.

This issue has become all the more pertinent now as more people are expected to return to work in their offices or factories as Malaysia prepares to enter the COVID-19 endemic phase in late October when 80 percent of the population is fully vaccinated.

"There are many positive things that we can learn from this pandemic. The issue of workplace safety and health became a major concern after the emergence of clusters that contributed to the rise in cases.

"This is where employers must play a proactive role in ensuring that the COVID-19 transmission risk is managed well in accordance with the level of risk at their workplace, as well as in terms of complying with the necessary SOPs," he said.