Article content Investigators with the University of Sydneyâs Lambert Initiative for Cannabinoid Therapeutics believe they have taken hold of a slippery proposition around THC: Does detection equate to impairment? Determining the precise amount of time someone is impaired after inhaling or orally ingesting weed does not come down to a specific number â given that response is individual â but researchers believe it may come down to a range. We apologize, but this video has failed to load. Try refreshing your browser, or Researchers say theyâve pinpointed how long THC is impairing, with smoking having shorter times than ingestion Back to video