How many slots are available for a 72D Direct commission? What type of candidates does the board want?

The army wants to fill in the direct commission slots with those that need the least amount of MOS training to be effective in the job and hit the ground running as an officer.

You skip OCS, so project in your board interview or packet things about you that convince them you'd succeed as an officer without OCS. Then project things in your professional history that support your knowledge of the MOS/Branch

Usually, 72D opens about 10-15 positions for year, for around 150-200 applicants. The board generally looks for people with direct experience and education related to environmental health, environmental science, engineering engineering, industrial hygiene, epidemiology, or related. Per the current rules, candidates are now restricted to no more than 10 years of active federal service, for people with prior TIS.