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.
Sarcopenia (from the Greek meaning poverty of flesh) refers to loss of muscle mass that occurs as a result of old age. It is characterized first by a decrease in muscle mass, which causes weakness and frailty. However, this loss of muscle mass may be caused by different cellular mechanisms than those that cause muscle atrophy. For example, during sarcopenia, there is a replacement of muscle fibres with fat and an increase in fibrosis.