You can block it. The unit won't heat or cool that room anymore though. The return air does effect supply air temp. And heat pump efficiency. With a 60 degree return air temp, the heat pump is more efficient then with a 70 degree return air temp.
We are simply getting contaminated causing otherwise healthy folks to lose the function of their kidneys and for a senior citizen who is already suffering sarcopenia this can be a death sentence because of the complexities associated with Renal Failure.
Symptoms can include weakness and loss of stamina, which can interfere with physical activity. Reduced activity further shrinks muscle mass. Although sarcopenia is seen mostly in people who are inactive, the fact that it also occurs in people who stay physically active suggests there are other factors in its development.