India, Dec. 7 -- Every winter, Delhi wakes up to an unsettling orange-grey haze that slows traffic, shuts schools, and overwhelms hospitals. For years this has been treated primarily as a public-health emergency. Yet it is equally an economic one. Air pollution now costs India nearly 1.3% of its GDP annually, driven by lost labour productivity, disrupted logistics, construction bans, and increased medical expenditure. A single smog episode can bring construction to a halt, cancel flights, and choke supply chains, costs that ultimately surface on the balance sheets of households, firms, and banks.

Delhi's crisis is therefore not an isolated urban problem. It is a microcosm of a deeper truth: climate and environmental degradation are alrea...