Delhi and Mumbai are classic examples of big cities with many satellite settlements.
Important updates through the day about the spread of SARS-CoV-2, the new coronavirus, around the world, its consequences for living, healthcare and productivity, and the global response.
More than 200 experts in aerosol science had publicly complained that WHO had failed to warn public about the risk of the coronavirus's ability to spread through tiny droplets floating in the air.
Aerosol concentrations can be reduced with increased ventilation, although recirculating the same air should be avoided unless the air can be filtered.
A vaccine works like a virus and initiates an immune response – but without causing major illness.