The colour of sky in most megacities (population >10 million) is rarely “blue” nowadays! This is because the densely packed high-rise buildings severely restrict the self-cleaning capabilities of compactly populated cities. Ever growing number of on-road vehicles, resuspension of the dust, and anthropogenic activities have been found to exacerbate the levels of ambient air pollution. Moreover, there is yet another mega pollution source that must be addressed: the cities themselves! Through the buildings’ high energy consumption, the cities themselves are indirect pollution sources. Most megacities are facing challenges nowadays in the quest for their sustainable growth, without compromising the air quality and urban way of life. When addressing urban sustainability, the issue of urban and building design, as well as human behaviour comes into the picture, as this is where huge gains can be made in energy reduction and air pollution. This is of particular importance for cities that will grow in megacities, and megacities which will grow into super megacities, in the next one or two decades, as is the compounding problem of global climate change and the impact this will have on indoor and outdoor air quality and energy consumption.

Our new directions article titled as “Can a “blue sky” return to Indian megacities”, recently published in Elsevier journal Atmospheric Environment, raises these issues. This article can be accessed online through this link for detailed information on this topic.