Paul died in July at age 70 due to “acute hypoxic respiratory failure,” according to multiple media reports on Friday about his death certificate.
As Healthline notes, “acute hypoxic respiratory failure” occurs when “your lungs cannot release enough oxygen into your blood, which prevents your organs from properly functioning.”
The US performer had also been diagnosed with two forms of cancer prior to his death.
One of the cancers, acute myelogenous leukemia, begins in the bone marrow “but most often it quickly moves into the blood,” according to the American Cancer Society.
The other was metastatic lung cancer, a form of lung cancer that “becomes advanced when it spreads to the other lung or spreads to other parts of your body,” WebMD notes.
Paul was reportedly set to be interred at Los Angeles’ Hollywood Forever Cemetery after cremation.
The comedian and actor had kept his cancer diagnoses private in his lifetime, but opened up to fans in a posthumous statement shared in late July.
“Please accept my apology for not going public with what I’ve been facing the last six years,” read the message, which was posted to Paul’s social media accounts.
“I have always felt a huge amount of love and respect from my friends, fans and supporters. I have loved you all so much and enjoyed making art for you.”
Captions for the posts described Paul as having “bravely and privately fought cancer for years with his trademark tenacity and wit”.
“A gifted and prolific talent, he will forever live in the comedy pantheon and in our hearts as a treasured friend and man of remarkable character and generosity of spirit,” the posts added.