Acrolein is a strong-smelling chemical that can irritate your lungs. When you breathe it in, it can cause your throat and lungs to feel sore and make it hard to breathe. It harms the tiny air sacs in your lungs, which help you get oxygen into your blood. This damage can lead to coughing, wheezing, or even serious breathing problems. So, acrolein can make your lungs unhealthy if you're exposed to it a lot.