KUALA LUMPUR: Ensuring good indoor ventilation at workplaces and business premises, educational institutions, places of worship and even residences is vital to stem the spread of Covid-19.
Health director-general Tan Sri Dr Noor Hisham Abdullah said there were three types of ventilation in buildings – natural ventilation, centralised air-conditioning system and non-centralised air-conditioning system.
Dr Noor Hisham said spaces with natural ventilation had lower risk of Covid-19 transmission as well as transmission of other airborne diseases since the density of the virus circulating in air could be reduced via dilution.
Nevertheless, he suggested for premises owners or residents of spaces with single-sided ventilation to keep more than one window or the door open, unless due to bad weather or poor air quality.
"Increase cross-ventilation by opening the window or door in the opposite direction and ensure that doors within the space remain open.
"Keep all windows in the space open to improve ventilation and promote more frequent exchange of clean air.
"Use fans to improve air circulation within the space," he said in a statement today.
For spaces with non-centralised air conditioning system, Dr Noor Hisham suggested for the windows to be lowered slightly if the air-conditioners were in use.
"Improve the ventilation indoors by opening the windows to allow frequent exchange of clean air into the building or premise.
"Switch on fans to enhance air circulation. Keep exhaust fans running to improve ventilation and promote exchange of (clean) air.
"It is also highly encouraged to set the temperature of the air-conditioner between 23 and 26 degree Celsius," he suggested.
As for spaces with centralised air-conditioning system, Dr Noor Hisham advised users to carry out checks to ensure all components and controls of the Centralised Mechanical Ventilation Air-Conditioning (MVAC) system were maintained and functioning as per design.
"Check the air filter seals to avoid bypass. and change the filters according to the (recommended maintenance) frequency.
"Increase outdoor fresh air ventilation by opening outdoor air dampers. Disable Demand Control Ventilation (DCV) if present in the MVAC system.
"It is advisable for the MVAC system to operate with maximum outdoor air uptake for two hours before and after occupancy to enable air flushing out of the premise.
"Users are also encouraged to upgrade the filters used in the existing Air Handling Unit (AHU) to at least MERV-14.
"Use air cleaners that utilise HEPA filters as an additional measure in the MVAC system and ensure that any modification or upgrading works of the existing MVAC system takes into account the current system's capacity and opinions from MVAC professionals," he said.
Dr Noor Hisham said other precautionary measures that must be exercised include limiting the number of people in a narrow space, ensuring that face masks are worn and maintaining physical distancing.
