Keep your air-con clean to stop Covid spread – WHO

If you want to use your air-conditioning unit in the workplace it will have to be regularly inspected, maintained and cleaned to help reduce the spread of Covid-19 indoors.

According to the World Health Organisation  (WHO) such a system attributed to increasing the rate of air change, reducing air recirculation and increasing the amount of outdoor air coming in.

“Settings that recirculate the air should not be used. Heating, ventilation and air-conditioning (HVAC) systems should always be regularly inspected, maintained, and cleaned,” WHO said.

There appears to still be limited research on the matter though.

Late last year, research published in the MedRxiv journal  suggested that poorly ventilated enclosed spaces may have a negative impact on the spread of Covid-19.

The research was based on three families who were in the same restaurant seated at tables next to each other with a 1m distance separating them from getting infected afterwards.

The research suggested that strong airflow from the air conditioner could have spread droplets from one table to the other two resulting in the families getting infected.

The researchers pinned this to a possible recirculation of contaminated air with a high concentration of infected droplet.

“It is important to note that our results do not show that long-range aerosol transmission of SARS-CoV-2 can occur in any indoor space, but that transmission may occur in a crowded and poorly ventilated space.”

According to the Global Heat Health Information Network(cited by WHO), if the air-conditioning or ventilation system was not well maintained and operated, there were two potential mechanisms through which it could contribute to virus transmission.

Firstly, the system itself could recirculate contaminated air or could create indoor conditions (temperature and humidity) that support virus survival.

“Buildings that use a central ventilation and/or climate control system, should use the most efficient filters.”

According to the South African labour department spokesperson Musa Zondi, the occupational health and safety act and environmental regulations for workplaces mention heating, ventilation and air conditioning (HVAC) systems or natural ventilation for workplaces.

“Split unit air-conditioners may not be effective in controlling exposure to Covid-19.

“The employer should rather rely on either mechanical ventilation (which is maintained, cleaned and provides the minimum number of air changes per person per hour) or natural ventilation (which focuses on the cross-flow of air within the workplace).”

Zondi said according to the regulation, split air-conditioners were not known for creating healthy ventilation at workplaces.

“Good ventilation should also be used in addition to other control measures, such as social distancing, limiting the number of employees in the workplace, regular cleaning and disinfecting of surfaces and providing masks.

“In addition to installing the HVAC system, the employer must still maintain the system, which includes regular maintenance and the cleaning of filters

“The HVAC systems must be capable of providing adequate fresh air or air changes, depending on the occupancy of the workplace,” Zondi said.

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