There is plenty of evidence that he at least new that TEL was extremely toxic - Midgley himself was poisoned by it. Despite this knowledge, he went on to insist

There is plenty of evidence that he at least new that TEL was extremely toxic - Midgley himself was poisoned by it. Despite this knowledge, he went on to insist it was safe for the public. As for CFC's, the evidence would suggest he did not know of their effects on atmospheric ozone. My reading of the article left me with the impression that Midgley's work on TEL and subsequent marketing was enough to condemn. His work on CFC's appears to be a very unfortunate follow-up.