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.
For his crimes Zeus sentenced him to eternal punishment. Prometheus was sent to the Caucasus Mountains and bound to a pillar. Every day a long-winged eagle ( known to be the symbol of Zeus) would come to visit Prometheus. The eagle would gnaw his liver. Prometheus, being a Titan, was immortal and could not die.