SA O.C. 90:26 mentions that one cannot say amidah in an area where there is a bad odor such as from feces.
There is a nursing home near my home that has a minyan. Occasionally, the hallway gets a bad odor from patients. On the other side of the shul wall is a dialysis center, and while most of the time there is no problem, occasionally a foul odor passes through the wall.
Some of the patients that join the minyan may have "accidents" during davening. We had this a few weeks ago, and we had to end davening prematurely. (Someone proposed continuing outside on the patio, but we couldn't move about 5 patients all in wheel chairs.)
Considering all these factors, there's a fairly high possibility of having a foul odor occur during the services, esp. on Shabbat or Yom Tov when services are longer (as quickly as we try to make it, anyway.) With this consideration can one still establish a minyan in such an environment in the first place?