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.
Understanding Sarcopenia. Sarcopenia is the age-related loss of muscle mass, strength, and functionality. It generally appears after the age of 40 and accelerates after the age of approximately 75. Although most often seen in physically inactive people, sarcopenia is also common in those who remain physically active throughout their lives.