Gurugram, Oct. 23 -- Beyond the broken roads, heaps of garbage and narrow lanes of Gadoli lies one of Gurugram's busiest firecracker markets, where business is picking up ahead of Diwali. Shops are stacked with colourful boxes of crackers, customers arrive to buy in bulk, and salesmen promise prices that keep buyers coming back.

At first glance, everything appears to be in order, with green firecrackers prominently displayed at storefronts. But behind these displays, another trade is flourishing; one where banned polluting firecrackers are being offered discreetly to customers who know what to ask for.

During an HT spot check on Wednesday, traders at Gadoli were found selling firecrackers without visible green certification markings, al...