An Oregon doctor who falsely claimed that wearing masks can lead to carbon monoxide poisoning has had his license revoked.

As of September 2, Steven Arthur LaTulippe is no longer allowed to practice, according to records from the Oregon Medical Board. LaTulippe also received a $10,000 fine.

An investigation conducted by the Oregon Medical Board found that LaTulippe engaged in "8 instances of unprofessional or dishonorable conduct, 22 instances of negligence in the practice of medicine, and 5 instances of gross negligence in the practice of medicine."