The oxygen level is quite low in the Ladakh region. If you are visiting the place for the first time, there are pretty good chances that you are left gasping. According to a recent research, the oxygen level across Ladakh, especially in the passes is 50% of what you would encounter in the plains.
The rarefied atmosphere can take time to adjust to and it is thus recommended that you spend a few days without any travel and acclimatize yourself. The good news is that widespread plantation drives and plantations have also helped improve the oxygen content in the recent years.