The cause of death for singer Sinéad O’Connor has been revealed a year after her tragic passing. According to TMZ, her death certificate lists multiple respiratory issues. The document states that O’Connor died due to chronic obstructive pulmonary disease (COPD), which was aggravated by bronchial asthma. She was also reportedly being treated for a respiratory tract infection, which was considered a contributing factor to her death. This information sheds light on the health struggles the singer faced in the final months of her life.