Why or how would a relatively inexpensive respirator have prevent this illness?

Case Study:

Your hobby is spelunking (cave exploration), but recently you haven’t been feeling too well. The doctor diagnoses Histoplasmosis (Histoplasma capsulatum).

This is the question that needs to be answered in the paper:

Why or how would a relatively inexpensive respirator have prevent this illness?

**attached are the guidlines for the paper.**