  A total of 188 high-mass outflows have been identified from a sample of 694
clumps from the Millimetre Astronomy Legacy Team 90 GHz survey, representing a
detection rate of approximately 27%. The detection rate of outflows increases
from the protostellar stage to the H II stage, but decreases again at the
photodissociation (PDR) stage suggesting that outflows are being switched off
during the PDR stage. An intimate relationship is found between outflow action
and the presence of masers, and water masers appear together with 6.7 GHz
methanol masers. Comparing the infall detection rate of clumps with and without
outflows, we find that outflow candidates have a lower infall detection rate.
Finally, we find that outflow action has some influence on the local
environment and the clump itself, and this influence decreases with increasing
evolutionary time as the outflow action ceases.
