As India grapples with a surge in COVID-19 cases, current efforts are largely focused on providing healthcare access to people battling COVID-19 and reducing the caregiver burden.

As such, we must think of prevention—how can we prevent transmission and reduce caseloads?

We, a group of air quality and public health researchers, have come together to answer some of the most common questions related to COVID 19 and its transmission through air.

• Use of appropriate masks. N95/KN95/KF94 masks are ideal.

• When used, they should cover both the mouth and nose. If such masks are not available, surgical masks or cloth masks with at least 2 or 3 layers can be used.

• Adequate and appropriate ventilation inside homes and other indoor and enclosed spaces (i.e., open windows, use of fans to increase air in-flow through windows).

• Avoiding crowded places- restaurants, trains, shopping areas & bazaars etc.

• In case of mild symptoms, isolate at home.

• In case a person who has tested positive for COVID-19 has to access common areas (e.g., bathrooms), avoid using them right afterward as the virus stays in the air for a few minutes.

Airborne transmission means that the aerosol carrying the virus can travel moderate distances by being exhaled from an infected person (even if they don’t have symptoms) and are carried on air currents.

These aerosols can travel farther than the distances we normally interact with other people when having conversations, and can continue to linger after a person has left the space.

Indoor and enclosed spaces are high risk zones since the aerosols which contain COVID-19 virus accumulate, unlike outdoors where they disperse quickly.

These include shops, malls, cinema halls, restaurants and pubs, public transportation (e.g., buses, trains), personal vehicles, enclosed religious spaces etc.

• Avoid meeting people indoors or in enclosed spaces if you can. Your chances of exposure to COVID-19 increase as you meet more people.

• If you have to meet/interact with someone indoors, make sure everyone around you is wearing a mask properly (i.e. mouth and nose are closed), keep your distance, and spend as little time in the enclosed space as possible.

• Keep windows open, if possible. Avoid shouting, talking too loudly or singing when in an enclosed space with people outside your household.

• When in a private and shared mode of transportation such as, car, bus, train or taxi, keep windows open. Allowing a crosswind is the quickest way to remove the infectious aerosols from the car.

The golden rule is to not meet people outside of your household for the next few weeks.

In case you absolutely have to meet someone outside your own household, meet them outdoors, in an open space, away from any crowds, while wearing proper fitting masks.

Make sure the mask covers both your mouth and nose properly and fits snugly on your face. Stay at least 2 m apart.

Masks such as N95/KN95/KF94 masks are ideal. Make sure the mask is tight fitting and covers both your nose and mouth; even better if it has a nose wire to prevent air from leaking out of the top of the mask. This can also prevent fogging of glasses.

If you are uncertain, wear two masks!

Since masks are not perfect, keep distance even if everyone is wearing them. Also, please wash your hands before using or handling the mask.

Surgical masks are better than simple cloth masks and are easily available in chemist shops and online stores.

If you can’t find them, use cloth masks with at least 2-3 layers.

Remember that using a folded handkerchief across your nose and mouth is not the same as wearing a mask.

This is not true. Masks can get uncomfortable when worn for long periods of time, but they are designed for people to wear and work in and are breathable.

In fact, even before COVID-19, people in many professions including healthcare workers, scientists, traffic policemen routinely use face masks.

Yes, it is possible to spread the virus even if you have no symptoms.

So beware that even a healthy-seeming person can spread the virus, and it is necessary to quarantine if you have been exposed for the full 12 days to prevent infecting others even if you feel absolutely fine.

In that case, please make sure that the person with COVID-19 isolates in a separate room and uses a separate bathroom, if possible.

Ensure proper ventilation- open windows and doors where possible and if available, keep air purifiers ON to trap the virus containing aerosol in the filter.

Everyone in the house should use face masks.

For a summary, you can also refer to the infographic which is now available in 10+ South Asian languages (download here).

(This explainer is developed by a team of air quality/aerosol and public health researchers including Pallavi Pant, Shahzad Gani, Faye McNeill, Asit Mishra, Christine Peters, and Rajshree Pandey)