varbasygau lujvo

x1=g1 ventilates fresh air x2=b1 for stale air x3=b2 in circumstances x4=b3

from vacri + basygau

In notes:

varbasygauca'a
x1=c1=g1 is a ventilator letting air x2=b1=v1 flow in and expells stale air x3=b2