Once coronavirus restrictions lift, we face huge changes in the way we go about our lives its been suggested that social distancing will continue until we have a vaccine (or treatment) for the virus , which could be another year.

When we eventually return to our workplaces, start commuting by bus, train and even plane, shop more regularly, and begin gathering at restaurants and bars again, should we be mindful of the air conditioning that is commonly used in these environments?

Opening windows and doors helps to keep fresh air circulating in enclosed spaces, which is why people who are self-isolating are encouraged to do both in their own homes. However, many offices, shops and restaurants (not to mention public transportation) rely on air conditioning to circulate air and regulate temperature. Can air conditioning systems spread coronavirus ?

How does COVID-19 spread?

To answer this question, we first need to talk about how the virus spreads. At the moment, we know COVID-19 can spread from person to person through small droplets expelled from the nose or mouth when a person coughs, sneezes, exhales or speaks. These droplets land on objects and surfaces around the person, according to the World Health Organization .

We can catch the virus by touching these objects or surfaces, then touching our eyes, nose or mouth. People can also catch COVID-19 if they breathe in droplets from someone the virus who coughs out or exhales smaller droplets (known as aerosols). This is why were urged to keep a distance of 6 feet from other people.

Whether or not the virus is airborne is fiercely contested. The World Health Organization suggests there isnt enough evidence to show the disease is airborne in an analysis of 75,465 COVID-19 cases in China, airborne transmission was not reported.

But airborne transmission might be possible in healthcare settings, especially during certain procedures or treatments (for example, disconnecting someone from a ventilator). This is why personal protective equipment (PPE) is so vital for healthcare workers.

Aerosols can travel in the air due to how tiny they are, carrying potential viral content quite some distance from where they originated.

But Paul Hunter , an infectious diseases expert and professor in medicine at the University of East Anglia, tells HuffPost UK: Although droplets actually have to move through the air [to infect someone], they dont tend to be airborne.

Airborne, in this sense, would mean the viruses could stay in the air for a long period of time and travel long distances to infect somebody, Hunter said. Although it is possible that COVID-19 is in certain circumstances airborne, it probably doesnt happen very often, he stresses.

Scientists in Finland have used modeling to show aerosol particles can remain in the air for several minutes after a person expels them either through coughing, sneezing or speaking then end up in the respiratory tract of others in the vicinity, according to Ville Vuorinen, assistant professor at Aalto University.

The concern is that aerosol particles could accumulate in public spaces by the virus hitching a ride on the droplets we expel when we cough, talk or breathe. Whether the virus can travel far enough, or linger long enough, to infect someone else through inhalation is as yet unknown.

Wearing face coverings such as homemade masks may reduce the number of droplets we expel, thereby reducing possible exposure in supermarkets and other crowded spaces. This is why some places now recommend face coverings in public settings.