Nepal has entered into modern development phase. The major cities including capital city Kathmandu are being developed. There are new roads under construction and older roads are expanding. The drinking water pipelines and new drainage system are also being installed. Because of these development works, road travel in Kathmandu has become a nuisance. You will see pedestrians walking with mask.
However, travelling by car is not a problem. We suggest you to close the windows and ask your driver to run the air conditioning system. We strongly advise you to use the air-conditioned cars only. The prices are slightly different for air-conditioned vehicles. This is the only way to get rid of the smoke and dust while touring in the under construction cities in a comfortable manner.