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.
Judge George O' Toole confirmed in court Wednesday that Boston bomber Dzhokhar Tsarnaev will face his death sentence at the US penitentiary in Terre Haute, Indiana, though a lengthy appeals process will likely precede his execution.