I haven't seen the pictures but if it were of a couple of guys smoking then this is why:
These guys work in shift, after about an hour of digging, it becomes physically impossible to dig on any longer, the lactic acid build-up is fast due to lack of oxygen and takes longer to shake off as the oxygen debt takes it's time. As for the smoking part, that's just to warm the lungs. EVERYBODY IN SIACHEN SMOKES, that's the only way to warm your lungs, otherwise, prolonged deep breathing makes you feel like you have a freezer in your chest and may lead to the lungs being filled with water. I think that's called oedema or something.