India, Nov. 7 -- Diwali comes from Deepavali, "a row of lamps." Not a row of explosions. Over the years, we've let the noise drown out the glow, forgetting that Diwali celebrates light's victory over darkness. It was never a contest for the loudest bang in the neighbourhood. Then comes the morning after, the same every year. A grey haze hangs over our cities, eyes sting, coughs linger and the air quality index lurches into the hazardous zone. Children, the elderly and anyone with asthma or a weak chest get the worst of it. So this Diwali has to be green. And no, that doesn't mean dull. Most of what it takes is already part of the festival.

Start with the diya. Clay lamps lit with ghee or sesame oil are the festival's truest symbol, and t...