As a 10-year-old living in Mumbai, Angad Daryani struggled to breathe during football matches because smog worsened his asthma. Now 23, he has found a solution -- capture the soot so it can be turned into something useful. In 2017, he launched the startup Praan to design a filterless purifier that can fit onto street lamps, apartment blocks and schools. Carbon Craft Design uses the captured carbon to create handcrafted decorative flooring tiles for restaurants, shops and hotels. Praan recently raised $1.5m (£1.1m) from US and Indian investors and plans to deploy the filtering devices at schools, hotels and industrial projects across India this autumn.