Is it permissible to perform tayammum to pray at work when in a state of janabah, intending to perform ghusl upon returning home, due to time constraints and the inability to perform ghusl in the morning?

Tayammum is only permissible when water is unavailable, or one is unable to use it, or its use would cause harm. Ghusl must be performed at home before going to work or at night if it becomes obligatory. If the time for prayer arrives and she has not performed ghusl, she must look for a place to perform it. If, after searching, she finds no means of purification and fears the prayer time will expire, then tayammum for prayer becomes obligatory.