Workers at this mine in Choa Saidan Shah dig coal with pick axes, break it up and load it onto donkeys to be transported to the surface.

Employed by private contractors, a team of four workers can dig about a ton of coal a day, for which they earn around $10 to be split between them.

The coalmine is in the heart of Punjab, Pakistan's most populous and richest province, but the labourers mostly come from the poorer neighbouring region of Khyber Pakhtunkhwa.