How COVID-19 spreads
When an infected person breathes, speaks, coughs or sneezes, they may spread particles containing the virus.
COVID-19 mostly spreads by aerosols — small virus particles that can stay in the air for minutes to hours. Good ventilation helps remove virus particles in the air.
You can reduce the risk of spreading COVID-19 by improving ventilation.
Ventilation when you have COVID-19
If you test positive for COVID-19, we recommend you self-isolate at home and avoid contact with people in your household for at least 5 days, even if you only have mild symptoms.
Some people who have tested positive for COVID-19 can still be infectious for up to 10 days. So, it is important to keep the air in your room fresh. If you can, open windows on different sides of the room to help airflow.
To stop virus particles spreading, reduce airflow from your room to other parts of your home:
- Block gaps under your door with a towel or draught stopper.
- Before opening the door into shared spaces, open your window for at least 5 minutes to freshen the air. Close the window before you open the door.
- In a shared bathroom or toilet, close the door after you have been in the room and switch on the extractor fan, or open a window.
How to improve ventilation at home
We encourage you to let in fresh air every day, including after someone visits your home.
If you can, partly open a window about 5cm for most of the day. Or open windows for at least 15 minutes as often as possible, whenever it is practical to do so.
Try 1 or more of these ways to remove stale air:
- Open windows or doors on opposite sides of a room to help airflow.
- Open doors between rooms to ventilate hallways and spaces without windows.
- In kitchens, bathrooms, and toilets, switch on the extractor fan or open a window.
- Open higher windows wider than lower windows. This helps reduce draughts.
- If your windows do not open, check if your ventilation system filters (cleans) the air.
When leaving windows or doors open for periods of time, consider the safety of others — especially disabled people, children and pets.
Steamed-up windows can be a sign of low ventilation.
In cold or wet weather
Try 1 or more of these ways to refresh air without letting rooms get chilly or damp:
- Partly open a window for most of the day, for example, a 5cm opening.
- Fully open a window or door for 3 to 5 minutes every hour.
- Open a window whenever you leave the room, closing the door behind you.
You do not have to leave windows or doors open all the time.
In homes with heat pumps or ventilation systems
Heat pumps, air conditioners and ceiling fans do not refresh the air. Instead, they move around air already in a room. You will need to open doors or windows to remove stale air and let in fresh air.
If you have a home ventilation system, check if it recycles air or filters air:
- If it recycles air, you need to open windows or doors to move stale air out and let in fresh air.
- If it filters or cleans air, this helps remove stale air and reduce the risk of virus particles spreading.
In rental properties
Landlords must provide good ventilation. If you live in or own a rental property, check ventilation rules on the Tenancy Services website.
Ventilation on public transport
Virus particles can build up quickly in crowded places such as buses or trains. It helps to sit or stand close to the door as airflow will be better.
Open a window on the bus if you can. Taxis and ride-share services often ask passengers to open windows.
We encourage you to wear a face mask in closed, crowded, and confined places such as public transport.
Last updated: at