ACT Health has developed the following ventilation guidance to reduce the risk of COVID-19 transmission.
It covers information on:
- well ventilated spaces
- why it’s important
- what you can do to improve ventilation, and
- taking actions to stay COVID Smart.
Please note this is general advice.
It does not replace individual assessment of locations by an experienced professional when considering changes to ventilation systems in buildings.
It also does not replace ACT Health advice for specific settings, like schools or high-risk settings, like hospitals.
Why is ventilation important as part of being COVID Smart?
COVID-19 can be spread from person to person through respiratory droplets and aerosol particles, which are released when people cough, sneeze, talk or shout.
Poorly ventilated indoor settings increase the risk of transmission of COVID-19 infection.
If a space is poorly ventilated, the number of infectious aerosols increases and may remain suspended in the air for some time and the risk of COVID-19 transmission increases.
Good ventilation helps to minimise the build-up of infectious aerosols.
Improving ventilation in conjunction with other COVID Smart behaviours can help to reduce the spread of COVID-19.
Whilst ventilation is important in reducing the risk of COVID-19 transmission, it does not replace other COVID-19 infection prevention and control measures like:
- staying at home if you have symptoms
- maintaining good hand and respiratory hygiene
- mask wearing in indoor environments where it is difficult to maintain physical distancing, and
- COVID Safe plans.
What are well ventilated spaces?
Ventilation is the deliberate introduction of fresh air and removal of stale air from a space to maintain or improve the air quality.
In indoor environments, well maintained heating, ventilation, and air conditioning systems (HVACS) may help to reduce the risk of virus transmission if recirculation mode is turned off.
What can I do to improve ventilation?
Different environments have different COVID-19 transmission risks, and it may not always be appropriate to use controls designed for one setting interchangeably with another.
There are some actions that you can take to improve ventilation.
Use outdoor settings wherever possible
In most cases, outdoor settings have better natural airflow than indoor areas.
Use large, well ventilated indoor spaces
Larger spaces allow physical distancing of >1.5metres. Combined with good ventilation the overall transmission risk is reduced.
Take steps to improve ventilation in indoor settings
Improving ventilation will dilute and disperse smaller particles suspended in the air.
Main ways that ventilation can be improved
There are 2 main ways that ventilation can be improved in indoor settings:
Natural ventilation refers to passive methods of improving air flow through a space, like opening windows and doors.
This is important in buildings that do not have mechanical ventilation systems.
Indoor ventilation can be improved by:
- opening doors and windows
- placing a fan facing toward an open window to increase air flow from inside to outside.
- avoiding directing fans towards people’s faces and aim them at the ceiling or floor instead
- limiting fan oscillation (swinging)
Avoid fans if a person present in the room has respiratory or covid-like symptoms and open doors or windows on opposite sides of the room to increase airflow through cross ventilation
The comfort and safety of others must always be considered with natural ventilation.
Do not open windows or doors if doing so poses a security, safety or health risk (for example, triggering asthma in a smoke or extreme pollen event, very cold or hot weather) to others.
Mechanical ventilation refers to the active process of introducing or removing air from an indoor space with powered air movement systems, like heating, ventilation, and air conditioning (HVAC) systems or exhaust fans.
Mechanical ventilation can be improved by:
- arranging regular inspection, cleaning and maintenance of HVAC systems by ventilation engineers and industrial or occupational hygienists
- changing air filters as recommended and following use in a contaminated area
- limiting or avoiding HVAC systems with air recirculation mode as this helps increase the amount of outdoor air being circulated into a space
- disabling ventilation controls with automated settings that reduce air supply based on temperature and occupancy
- ensuring exhaust fans in kitchens, restrooms and communal areas are functional and operating at full capacity
- installing whirlybirds or extractor fans to enhance overall ventilation strategy.
Air purifiers or cleaners such as those fitted with high-efficiency particulate air (HEPA) filters can lower the concentration of airborne contaminants, including viruses, in the air and are useful additions in areas with poor ventilation.
It is important to consider the filtration capacity required and to place in a location that does not interfere with existing HVAC airflow.
Air purifiers or cleaners should be operated and maintained in accordance with the manufacturer’s instructions.
Businesses should consider consulting an occupational hygienist to assist in determining appropriate placement of these devices within the room to ensure maximum benefit is achieved.
What if I can’t change ventilation or choose an outdoor location
If you can’t change ventilation in your indoor space or choose an outdoor location, consider the following:
- reducing the number of people in an indoor space at any one time
- reducing the length of time people spend indoors together
- avoiding peak activity times and places where people gather indoors
- wearing a well fitted face mask when indoors
- optimising ventilation by periodically opening a window (for example, every 10 minutes at every hour if the weather is too cold or supervision is needed near an open window)
- Safe Work Australia: Improving ventilation in indoor workplaces
- Australian Government Department of Health: Australian Health Protection Principal Committee (AHPPC) statement on the role of ventilation in reducing the risk of transmission of COVID-19
- World Health Organization: Coronavirus disease (COVID-19): Ventilation and air conditioning