Why indoor air quality is of utmost importance when workplaces gradually resume operations?

Date: 30 August 2020

Many facilities managers are struggling with a couple imminent question in front of them:

  1. How to get the facility management team back to some semblance of normal in this era of the coronavirus?
  2. What can be done to keep the virus from spreading within the building premises facilities?

A few facilities and industrial buildings have remained totally opened during the circuit breaker period in Singapore, while most others are either fully closed or partially open with reduced staffing. As these workplaces and facilities gradually re-open, facility managers need to make sure that the necessary steps are taken to reduce/eliminate the exposure to coronavirus.

At first glance, it might appear all that needs to be done to our facilities is a deep cleaning, make sure people space themselves out (social distancing), and make sure that people’s gathering/meeting, is done virtually wherever and whenever possible. However, even after providing with strict rules and demarcations to follow, it gets much more complicated, as there are many variables to be taken into consideration.

A few of the variables to take into consideration for maintaining air quality in empty/partially occupied facilities are listed here below:

  • It is a well-established fact that increasing the flow of clean air into an occupied space can help reduce the spread of infectious diseases as facilities begin to reopen operators should prioritize a focus on air quality and air flow into the work spaces. However, maintaining indoor environmental conditions is of primary importance—specifically, controlling relative humidity.
  • Operating building HVAC and mechanical systems to minimize and control relative humidity during partial and complete closures is critical in order to avoid the growth of mold in occupied spaces and HVAC systems. 
  • Building heating, ventilation, and air-conditioning (HVAC) systems are designed to operate under a heat load produced by people, computers, lights, and other activities. People working from home and other altered occupancy patterns reduce a building’s heat load, which can affect an HVAC system’s ability to control relative humidity levels, creating conditions for possible mold and moisture damage to occur. This is specifically important for a country like Singapore, located in hot tropical region where sun and rain are the two weather patterns throughout the year.
  • Operating cooling towers during a building or campus shutdown poses another challenge in preventing Legionnaires’ disease. Reduced HVAC system demand and limited availability of maintenance staff can allow conditions to degrade and Legionella bacteria to multiply.
  • Coincidentally, symptoms of Legionnaires’ disease are similar to those of COVID-19, both typified by fever, cough, and shortness of breath potentially causing ‘sick building syndrome’ [1]. 

To control these major variables, there are 3 proposed phases in which air quality management at workplaces could be implemented:

Phase 1
What needs to be done now to manage air quality?

Phase 2
What should be done when the building reopens for partial occupancy?

Phase 3
The strategy for the future, once the building is ‘fully operational’?

Phase 1 & 2

Since most workplaces in Singapore are at least partially open and operational, we can combine Phase 1 and 2.

1. During these phases, the building systems has reduced occupancy (temporary). Hence, you can consider turning off or adjusting the temperatures for specific sections of the building’s heating, ventilating and air conditioning (HVAC) system. You can also increase the percentage of fresh air intake from the outside air, which should save a bit from your utility bill.

2. Ensure that the security system and emergency systems (generators, fire detection and sprinkler devices, etc.) are operational by frequently checking them and conducting essential maintenance.

3. Ensure that the air filters are changed frequently. In one of our previous email campaigns [2], we have provided the rationale of selection of appropriate filter ratings. (Filters should have adequate MERV ratings minimum of MERV 13 and ideally HEPA filters rated for MERV 16)

4. Conducting testing for Legionella bacteria is critical before building operations resume fully.

Phase 3

‘Fully operational’ does not mean getting all workforce will get back to the occupancy during pre-coronavirus levels. The Singapore Ministry of Health has provided specific advisories to work from home as much as possible [3] as it is likely that social distancing guidelines will still be in place as a part of the ‘new normal’.

Facility management professionals should be ahead of the curve in thinking about the work environment change, and then prepare for these changes. This process is a continually improving and modified task. There are some guidelines available from the American Industrial Hygiene Association (AIHA) has published a guidance document for workplace cleaning [4]. They also have published resources focused on specific building types such as restaurants and fitness centres—these may be of value to facilities managers whose buildings contain cafeterias and gyms.

Some of the recommendations provided in the documents are highlighted here below: 

- Conducting Air Quality Assessment prior to occupation of the premises.

- Use only HEPA filtered vacuum cleaners and AHU filters, to avoid aerosolizing respirable dust that may contain infectious pathogens. 

- For deep carpet cleaning, use hot water injections that continually deliver water above 140ºF (60ºC).

- Do not use foggers as a substitute for applying disinfectant directly onto a surface. The US-EPA does not recommend fogging[5] to control COVID-19: “Fumigation and wide-area spraying are not appropriate tools for cleaning contaminated surfaces.”


These changes and improvements will have to continue for the foreseeable future, with considerable data collected and put into reports for the facilities manager to analyse. Analyses should be scheduled fortnightly or during regular monthly meeting to observe the trends. That is the only way that one can evaluate post-coronavirus era. These IAQ improvement solutions can be implemented gradually as part of existing operational budgets.

Industrial hygienists and Indoor Air Quality consultants are able to help facility management conduct Air Quality Assessments as well as review toxicity and effectiveness of disinfectant chemicals, identify safe remediation practices, assess the risk, and develop management plans to control other building-related hazards. For detailed advice on assessment and specific control measures for your workplace, please mailto:consulting@iom-world.sg 


[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2796751/

[2] Understanding Building Ventilation and HEPA filtrations systems in midst of COVID-19

[3] https://www.moh.gov.sg/covid-19/advisories-for-various-sectors

[4] https://aiha-assets.sfo2.digitaloceanspaces.com/AIHA/resources/Guidance-Documents/Workplace-Cleaning-for-COVID-19-Guidance-Document_FINAL.pdf

[5] https://www.epa.gov/coronavirus/can-i-use-fumigation-or-wide-area-spraying-help-controlcovid-19



WHO. (2020). COVID-19 Strategy Update [Ebook]. WHO. Retrieved from https://www.who.int/docs/default-source/coronaviruse/covid-strategy-update14april2020.pdf?sfvrsn=29da3ba0_19

OSHA. (2020). COVID-19 Safety and Health Topics & News, from https://www.osha.gov/SLTC/covid-19/

CDC. (2020). Prepare your Small Business and Employees for the Effects of COVID-19 [Ebook]. CDC. Retrieved from https://www.cdc.gov/coronavirus/2019-ncov/downloads/guidance-small-business.pdf

US-EPA. (2020). Guidance for Cleaning and Disinfecting Public Spaces, Workplaces, Businesses, Schools and Homes https://www.epa.gov/coronavirus/guidance-cleaning-anddisinfecting-public-spaces-workplaces-businesses-schools-and-homes

CDC. (2020). Coronavirus Disease 2019 (COVID-19). from https://www.cdc.gov/coronavirus/2019-ncov/php/building-water-system.html 

[1] https://www.mdpi.com/2076-3298/5/1/4

[2] https://www.straitstimes.com/singapore/green-buildings-also-better-for-health-not-just-more-energy-efficient-bca-study

[3] https://friendlybuildings.bca.gov.sg/industry-professional-ud-7-principles-of-ud.html?scroll=content

[4] https://www.bca.gov.sg/GreenMark/others/GM_HW_2018_Pilot.pdf

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