Covid-19 Ventilation Guidelines Urgently Needed

By Dr Milton Lum |

There is an urgent need for ventilation guidelines that take into account the accepted evidence that Covid-19 also spreads by aerosols.

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With increases in the body of knowledge, the World Health Organization’s (WHO) statements on the modes of spread of SARS-CoV-2, the causative agent of Covid-19, has changed with time.

Where previously respiratory droplets and close contact were considered the primary modes of spread, aerosols have been recognised as another major mode of spread in late 2020.

On March 29, 2020, the WHO stated, “Respiratory infections can be transmitted through droplets of different sizes: when the droplet particles are >5-10 μm in diameter they are referred to as respiratory droplets, and when then are <5μm in diameter, they are referred to as droplet nuclei. According to current evidence, Covid-19 virus is primarily transmitted between people through respiratory droplets and contact routes… In the context of Covid-19, airborne transmission may be possible in specific circumstances and settings in which procedures or support treatments that generate aerosols are performed”.

On December 13, 2020, the WHO stated, “The virus can spread from an infected person’s mouth or nose in small liquid particles when they cough, sneeze, speak, sing or breathe. These particles range from larger respiratory droplets to smaller aerosols”.

  • Current evidence suggests that the virus spreads mainly between people who are in close contact with each other, typically within one metre (short-range). A person can be infected when aerosols or droplets containing the virus are inhaled or come directly into contact with the eyes, nose, or mouth.
  • The virus can also spread in poorly ventilated and/or crowded indoor settings, where people tend to spend longer periods of time. This is because aerosols remain suspended in the air or travel farther than one metre (long-range).

People may also become infected by touching surfaces that have been contaminated by the virus when touching their eyes, nose or mouth without cleaning their hands.”

The role of aerosols in the spread of Covid-19 was previously addressed in a CodeBlue article in August 2020.

Ventilation Guidelines

Since then, the WHO and regulators in several countries have published ventilation guidelines for the control of Covid-19.

On March 1, 2021, the WHO, in the executive summary of its publication Roadmap To Improve And Ensure Good Indoor Ventilation In The Context Of Covid-19, stated, “The risk of getting Covid-19 is higher in crowded and inadequately ventilated spaces where infected people spend long periods of time together in close proximity. These environments are where the virus appears to spread by respiratory droplets or aerosols more efficiently, so taking precautions is even more important. Understanding and controlling building ventilation can improve the quality of the air we breathe and reduce the risk of indoor health concerns including prevent the virus that causes COVID-19 from spreading indoors.”

The Centers for Disease Control (CDC) in the United States have identified various methods to improve ventilation that include:

  • Increase the introduction of outdoor air.
  • Use fans to increase the effectiveness of open windows.
  • Ensure ventilation systems operate properly and provide acceptable indoor air quality for the current occupancy level for each space.
  • Rebalance or adjust heating, ventilation and air conditioning (HVAC) systems to increase total airflow to occupied spaces when possible.
  • Turn off any demand-controlled ventilation (DCV) controls that reduce air supply based on occupancy or temperature during occupied hours.
  • Improve central air filtration.
  • Ensure restroom exhaust fans are functional and operating at full capacity when the building is occupied.
  • Inspect and maintain exhaust ventilation systems in areas such as kitchens, cooking areas, etc.
  • Use portable high-efficiency particulate air (HEPA) fan/filtration systems to enhance air cleaning (especially in higher risk areas such as a nurse’s office or areas frequently inhabited by people with a higher likelihood of having Covid-19 and/or an increased risk of getting Covid-19).
  • Generate clean-to-less-clean air movement by evaluating and repositioning as necessary, the supply louvers, exhaust air grilles, and/or damper settings.
  • Use ultraviolet germicidal irradiation (UVGI) as a supplemental treatment to inactivate SARS-CoV-2 when options for increasing room ventilation and filtration are limited.
  • In non-residential settings, run the HVAC system at maximum outside airflow for two hours before and after the building is occupied.


Some of the CDC’s interventions were based on the American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Guidance for Building Operations during the Covid-19 pandemic.

The CDC stated that “not all interventions will work in all scenarios. Use caution in highly polluted areas when increasing outdoor air ventilation”.

The European Centre for Disease Prevention and Control (ECDC) issued the first update on its publication, Heating, Ventilation And Air-Conditioning Systems In The Context Of Covid-19, on November 11, 2020. It stated, “It is now well-established that Covid-19 transmission commonly occurs in closed spaces;

  • If well-maintained and adapted for use in the Covid-19 pandemic, heating, ventilation and air-conditioning (HVAC) systems may have a complementary role in decreasing potential airborne transmission of SARS-CoV-2;
  • Four bundles of non-pharmaceutical interventions (NPIs) should be considered to reduce potential airborne transmission of SARS-CoV-2 in closed spaces: the control of Covid-19 sources in closed spaces; engineering controls in mechanically ventilated (by HVAC systems) and naturally ventilated closed spaces; administrative controls; and personal protective behaviour.”

The National Environment Agency (NEA) of Singapore issued its publication, Guidance On Improving Ventilation And Indoor Air Quality In Buildings Amid The Covid-19 Situation, on May 25, 2021, based on the Singapore Standard SS554: Code Of Practice For Air Conditioning And Mechanical Ventilation In Buildings.

It stated, “Covid-19 is mainly transmitted by close contact and respiratory droplets which are released when an infected person coughs, sneezes, talks, or sings. It can also be spread through virus aerosols in the air under certain settings, such as enclosed environments which are poorly ventilated. Hence, it is critical to mitigate this risk by improving ventilation and air quality in indoor environments.”

Its guidance included measures for:

  • Air-conditioned premises with mechanical ventilation provision e.g. centralised air-conditioning system.
  • Enclosed air-conditioned premises without mechanical ventilation provision e.g. split-unit air-conditioners or fan coiled units (FCUs) without fresh air supply.
  • Naturally ventilated premises.

Stop Wasting Resources

The Ministry of Housing and Local Government has been carrying out public sanitisation exercises since April 2020, presumably based on the Health Ministry’s outdated publication, Garis Panduan Pembersihan Dan Disinfeksi Di Tempat Awam, dated April 3, 2020.

These public sanitisation exercises were continued, despite data and advisories from the WHO, CDC and ECDC that it is not necessary, effective or recommended. In addition, there are questions as to whether consideration was given to the adverse health hazards from the chemicals used e.g. chlorine based agents.

According to the Ministry, from March 2020 to May 29, 2021, 25,252 sanitation operations had been carried out. Its minister stated, “More aggressive action must be taken and the sites to be covered include housing areas, markets and so forth. It is hoped that this effort will help reduce the spread of Covid-19”.

The Ministry’s position has been, and continues to be devoid of any scientific basis and a waste of the country’s limited resources.

No information has been provided on the millions of ringgit expended on these activities. Who benefited from the public sanitisation exercises? The public? Suppliers? Anyone else?

Consider how many Covid-19 patients would have benefited from the monies expended.

Ventilation Guidelines Urgently Needed

Malaysia continues to climb the global Covid-19 league with newer milestones in the past month.

On June 24, 2021, Malaysia’s position in the global ranking of cumulative cases reached 36th, up from the 39th position on May 31, 2021 and the 85th position on November 18, 2020. Malaysia also has the highest daily number of newly confirmed cases per million population and the daily number of deaths per million population in ASEAN.

The data reflects the indisputable fact that there is widespread community spread of Covid-19. In practical terms, it means that everyone is at risk of getting infected, even if there is strict compliance to physical distancing, mask wearing, frequent handwashing, and avoidance of crowds, confined spaces and close contacts.

There is a predominance of work clusters in the daily reports of the Health Ministry. Many workplaces and even homes, have ventilation issues, particularly indoors, all of which contribute to the spread of Covid-19.

There is an urgent need for ventilation guidelines that take into account the accepted evidence that Covid-19 also spreads by aerosols.

Instead of focusing on unproductive public sanitisation exercises, the Ministry of Housing and Local Government can make an effort to boost its public image by co-operating and collaborating with the Ministry of Health to produce ventilation guidelines urgently needed for workplaces and homes, as well as to update sanitisation guidelines.


Dr Milton Lum is a Past President of the Federation of Private Medical Associations, Malaysia and the Malaysian Medical Association. This article is not intended to replace, dictate or define evaluation by a qualified doctor. The views expressed do not represent that of any organisation the writer is associated with.

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