Hello, I'm having a hard time understanding what an exacerbation is like; does it come gradually over the days, or it happens out of nowhere in a sudden manner? My dad had been smoking for 42 years, 3 years ago he developed a chronic cough that got worse over time, and this year he started having quite severe shortness of breath after coming from the grocerie store near our house. He said his lungs were fine and a month ago, one wednesday morning, he seemed fine and out of nowhere started having shortness of breath, mom called emergency, it took 10-15 minutes for doctors to arrive, it seemed dad had low oxygen levels and nothing helped so he passed away. He had been having sleep issues a week prior, so I don't know if the exacerbation started gradually a week before, or it was that morning... We didn't know he had COPD