Aarish, 15, sits on a hospital bed in the central Indian state of Madhya Pradesh. A pair of dark glasses hides a painful injury in his left eye.

His cornea was damaged a week ago when an improvised firecracker device that he bought to celebrate the Diwali festival exploded near his face, causing him to lose vision in one eye. He has undergone emergency surgery and his doctor says only time will tell how much sight he can regain.

The teenager, who doesn't go to school, says he's most worried about missing work - his father works as a gardener and Aarish repairs televisions to supplement the family income. Child labour is illegal in India, but millions of children work. Indian law allows children above 14 years to work in some industries which are seen as non-hazardous.

Aarish is among hundreds of children and young adults from at least five states across northern India who have suffered serious eye injuries from using the same kind of device - called "carbide guns" - during Diwali.

The "carbide gun", a rudimentary device, using calcium carbide in a plastic pipe, gives dramatic results - a loud blast that sounds like a gunshot, accompanied by fiery sparks. But the explosion is unpredictable and often delayed - officials told the BBC that many of the injuries occurred when children peeped inside the pipe to check just as the blast happened.

The sale and purchase of calcium carbide is regulated in India, but farmers and shopkeepers often use it to artificially ripen fruit. Police officials also say the crude guns are sometimes used to scare away animals from fields.

But many in India had not heard of these guns until last week, when a........

© BBC