Do’s & Don’t for Indoor/Outdoor Sanitisation Protocol for Covid-19 Prevention

Covid-19 Preventive Mechanism: Shall We Improve on Indoor Air Quality(IAQ) or Focus on Sanitisation?

The recent exchange of words between academia and government agencies pertaining to sanitisation is a waste of resources, has become an extreme debate and welcome more responses from Malaysian across all sectors. Both sides are debating two different matters, where Dr. Adeeba is strengthening the use of masks and improving ventilation, which is more on prevention measures while the Fire Department talking about the control mechanism – indoor surface or high-touch point, sanitisation helps Malaysia reduce the risk of cross contamination at indoor spaces and as well in public spaces of the contaminated area. It is not about who is right or wrong, the important point here is we should know what causes the transmission of SARS-CoV-2 (Covid-19) and the best ways to prevent the transmission from one person to another.

How does Covid-19 transmit from one person to another?

Transmission of SARS-CoV-2 can occur through direct, indirect, and/or close contact with infected people through infected secretions such as saliva and/or respiratory secretions or their respiratory droplets, which are expelled when an infected person coughs, sneezes, talks or sings. Respiratory droplets are >5-10 μm in diameter where the transmission can occur when a person is in close contact (within 1 metre) with an infected person who has respiratory symptoms (e.g. coughing or sneezing). Meanwhile, airborne transmission is defined as the spread of an infectious agent caused by the dissemination of droplet nuclei (aerosols) that remain infectious when suspended in air over long distances and time. 

On the other hand, respiratory secretions or droplets expelled by infected individuals can contaminate surfaces and objects, creating fomites (contaminated surfaces). Viable SARS-CoV-2 virus and/or RNA detected by RT-PCR can be found on those surfaces for periods ranging from hours to days, depending on the ambient environment (including temperature and humidity) and the type of surfaces.  In an analysis of 75,465 COVID-19 cases in China, 78-85% of clusters occurred within household settings, suggesting that transmission occurs during close and prolonged contact both indoors and outdoors.


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Emphasis on Prevention Measures: Awareness and Understands the Importance of Good Indoor Air Quality

While many are debating about deep cleaning and sanitisation, the public shall be educated on the risk of poor ventilation which directly increases the risk of infection in crowded and/or confined spaces. As virus-carrying aerosols are exhaled, so too is CO2. As when ventilation is poor, CO2 accumulates along with the virus. WHO recommends a minimum ventilation rate of between 6–12 air changes an hour — in which the entire volume of air in the room is replaced — to prevent airborne transmission of pathogens in healthcare facilities, but a lower rate of air changes for other venues. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) establishes minimum standards for indoor air quality. Recommended targets are as low as 0.35 air changes per hour for homes, 2–3 for offices, 5–6 for schools and 6–12 for hospitals.

During Covid-19 pandemic, it is highly recommended to improve the air circulation and increase the air change rate. In addition, it is recommended to dilute the air with as much fresh air as possible.  For home and office with split units, it is advisable to open the window daily to exhaust the indoor air and replace it with fresh air. Meanwhile, buildings with centralised air conditioning systems increased the fresh air intake to the air handling units but cautions with the increase of relative humidity that may also contribute to the suitable environment for viruses to survive and be transmitted.

Improving the ventilation alone is not enough. Each of us shall be able to remind ourselves to practice 3W which is to wash hands frequently and sanitise, wear masks and warn people who neglect the good practices in preventing the transmission of viruses. Wearing a mask is more effective in preventing the risk of infection in indoor spaces. Recently, the Ministry of Health of Malaysia has recommended wearing a double mask to increase self-protection. We must stay safe and stay protected at all times. 

Sanitisation Practice Is Compulsory When You Fail to Prevent The Transmission: What is The Correct Way?

In a safety point of view, the use of masks ranks the lowest in the hierarchy of controls as the provision of personal protective equipment (PPE) because the hazard, which is the virus, still lingers around without us knowing. No doubt improving ventilation is one of the best ways to tackle the pandemic and formation of clusters because it involves engineering control which ranks in the top three of controls of transmission. Let’s put ourselves in the situation, wouldn’t it be better to eliminate the risk of transmission and fortify the area with other controls mentioned above? Since SARS-CoV-2 can be spread through airborne water droplets and direct contact with a contaminated surface, proper sanitisation will provide a safer environment as the risk is temporarily lifted until another person with confirmed positive COVID-19 unknowingly enters the area. 

Now let’s look at the situation from an environmental health point of view, minimising the transmission of infectious diseases is the core function of the public health law. The appropriate exercise of legal powers will vary according to the seriousness of the disease, the means of transmission, and how easily the disease can be spread. Epidemiologically speaking, the transmission triangle consists of the host, the virus and the environment. The host in this case is the human body where we can break the chain by practicing social distancing, provision of face masks, using hand sanitisers and providing vaccinations. What do we do about the virus and the environment? We can either inactivate the virus or make the environment safer, which both can be done by proper sanitisation practice. The word “proper” here is emphasised because improper practices will cause false hope for the public and an unsafe environment. 

This is why the Ministry of Health (KKM) has repeatedly enforced and gives awareness to the public for sanitisation procedures and management. In Appendix 4 of Annex 25 COVID-19: Management Guidelines for Workplaces and Annex 36 Guidelines for Cleaning and Disinfection for Public Places, both had clearly listed the proper procedures from the schedule, planning, equipment to use, clothing to use, ways of preparing the disinfectant until post-care and maintenance of the safe environment. In a nutshell, there is no wrong or right way but a “proper” solution to handle the situation. 

By Salina Hang Jebat

Indoor Environmental Hygienist / Certified IAQ Assessor

Enviro Group Asia delivers the best total solutions in Indoor Environmental Technologies and Engineering Services to ensure a healthier and safer indoor environment. With the single and most game-changing vision of ‘Protecting People, Protecting Assets” by providing a cleaner and healthier indoor environment, Enviro Group Asia has successfully grown from one entity to a group with multiple subsidiaries, all with its own unique specialisations that work hand-in-hand towards the founding vision.

We continue to invest in R&D, in the area of indoor environmental engineering process as we believe continuous learning is the key in order to provide sustainable protection to the public. With 15 years of experience and combined technical expertise of more than 30 years, we pride ourselves on our knowledge and our expertise. We create Partnerships and not clients.

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Enviro Group TeamReferences:

  • Lewis, Dyani. “Why indoor spaces are still prime COVID hotspots.” Nature, vol. 592, 2021, pp. 22-25. Nature,
  • “Transmission of SARS-CoV-2: Implications for Infection Prevention Precautions.” World Health Organisation, Accessed 9 July 2020.