Natural Ventilation on Busses

`Is it possible to have windows that can be opened installed on current busses? 

The idea of being in an enclosed space with a number of people scares me so I have stopped using bus services completely during Covid. 

I would use the bus again if it was possible to have large windows open to encourage natural ventilation.  This would also be of great help during the sweaty summer months. In Malta we have great weather and for most of the year natural ventilation will be more effective than ACs.